DOW CHEMICAL CO /DE/
SC 13D/A, 1995-05-08
CHEMICALS & ALLIED PRODUCTS
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<PAGE>
 



                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549



                                SCHEDULE 13D/A
                   Under the Securities Exchange Act of 1934
                               Amendment No. 20


                            MARION MERRELL DOW INC.
                            -----------------------
                               (Name of Issuer)


                    COMMON STOCK, par value $0.10 per share
                    ---------------------------------------
                        (Title of Class of Securities)


                                  569713-10-0
                                  -----------
                                (CUSIP Number)


                                 John Scriven
                      Vice President and General Counsel
                           The Dow Chemical Company
                                2030 Dow Center
                            Midland, Michigan 48674
                                (517) 636-5914
               -------------------------------------------------
                (Name, Address and Telephone Number of Person 
               Authorized to Receive Notices and Communications)




                                  May 3, 1995
                                  -----------
            (Date of Event which Requires Filing of this Statement)




If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
Schedule because of Rule 13d-1(b)(3) or (4), check the following box [_].


Check the following box if a fee is being paid with this statement [_].




                                 Page 1 of 11
<PAGE>
 



                             CUSIP No. 569713-10-0
                                       -----------

- ------------------------------------------------------------------------------

 1)   Name of Reporting Persons and its          RH Acquisition Corp.,
      I.R.S. Identification No.                  a wholly owned subsidiary of
                                                 The Dow Chemical Company
                                         
- ------------------------------------------------------------------------------

 2)   Check the Appropriate Box if a             (a) [_]
      Member of a Group                          (b) [x]
                                         
- ------------------------------------------------------------------------------
     
 3)   SEC Use Only
 
- ------------------------------------------------------------------------------
     
 4)   Source of Funds                            AF
      
- ------------------------------------------------------------------------------

 5)   Check Box if Disclosure of Legal                                  
      Proceedings is Required Pursuant           [_]
      to Items 2(d) or 2(e)
                                
      
- ------------------------------------------------------------------------------
      
 6)   Citizenship or Place of Organization       Delaware
     
- ------------------------------------------------------------------------------
                          
                     7) Sole Voting Power        55,934,100/1/   20.2%/2/
     NUMBER OF            
                             
      SHARES       -----------------------------------------------------------
                          
   BENEFICIALLY      8) Shared Voting Power      0 
                          
     OWNED BY                    
                   -----------------------------------------------------------
       EACH             
                     9) Sole Dispositive Power   55,934,100/1/   20.2%/2/
    REPORTING             
                         
      PERSON       -----------------------------------------------------------
                          
       WITH         10) Shared Dispositive Power 0   
                                 
- ------------------------------------------------------------------------------
      
11)   Aggregate Amount Beneficially              55,934,100/1/   20.2%/2/
      owned by Each Reporting Person
      as of May 3, 1995 

- ------------------------------------------------------------------------------

12)   Check Box if the Aggregate Amount          [_]                        
      in Row (11) Excludes Certain Shares
                     
- ------------------------------------------------------------------------------

13)   Percent of Class Represented by            20.2%/2/
      Amount in Row (11) as of 
      May 3, 1995 

- ------------------------------------------------------------------------------

14)   Type of Reporting Person                   CO
      
- ------------------------------------------------------------------------------




                                 Page 2 of 11
<PAGE>
 




                             CUSIP No. 569713-10-0
                                       -----------

- ------------------------------------------------------------------------------

 1)   Name of Reporting Persons and its          Dow Holdings Inc.,    
      I.R.S. Identification No.                  a wholly owned subsidiary of
                                                 The Dow Chemical Company
                                         
- ------------------------------------------------------------------------------

 2)   Check the Appropriate Box if a             (a) [_]
      Member of a Group                          (b) [x]
                                         
- ------------------------------------------------------------------------------
     
 3)   SEC Use Only
 
- ------------------------------------------------------------------------------
     
 4)   Source of Funds                            AF
      
- ------------------------------------------------------------------------------

 5)   Check Box if Disclosure of Legal                                  
      Proceedings is Required Pursuant           [_]
      to Items 2(d) or 2(e)
                                
      
- ------------------------------------------------------------------------------
      
 6)   Citizenship or Place of Organization       Delaware
     
- ------------------------------------------------------------------------------
                          
                     7) Sole Voting Power        75,000,000/1/   27.1%/2/
     NUMBER OF            
                             
      SHARES       -----------------------------------------------------------
                          
   BENEFICIALLY      8) Shared Voting Power      0 
                          
     OWNED BY                    
                   -----------------------------------------------------------
       EACH             
                     9) Sole Dispositive Power   75,000,000/1/   27.1%/2/
    REPORTING             
                         
      PERSON       -----------------------------------------------------------
                          
       WITH         10) Shared Dispositive Power 0   
                                 
- ------------------------------------------------------------------------------
      
11)   Aggregate Amount Beneficially              75,000,000/1/   27.1%/2/
      owned by Each Reporting Person
      as of May 3, 1995 

- ------------------------------------------------------------------------------

12)   Check Box if the Aggregate Amount          [_]                        
      in Row (11) Excludes Certain Shares
                     
- ------------------------------------------------------------------------------

13)   Percent of Class Represented by            27.1%/2/
      Amount in Row (11) as of 
      May 3, 1995 

- ------------------------------------------------------------------------------

14)   Type of Reporting Person                   CO
      
- ------------------------------------------------------------------------------




                                  Page 3 of 11
<PAGE>
 



                             CUSIP No. 569713-10-0
                                       -----------

- ------------------------------------------------------------------------------

 1)   Name of Reporting Persons and its   The Dow Chemical Company
      I.R.S. Identification No.           I.R.S. Identification No. 38-1285128
                                                                         
                                         
- ------------------------------------------------------------------------------

 2)   Check the Appropriate Box if a             (a) [_]
      Member of a Group                          (b) [x]
                                         
- ------------------------------------------------------------------------------
     
 3)   SEC Use Only
 
- ------------------------------------------------------------------------------
     
 4)   Source of Funds                            WC, BK, OO
      
- ------------------------------------------------------------------------------

 5)   Check Box if Disclosure of Legal                                  
      Proceedings is Required Pursuant           [_]
      to Items 2(d) or 2(e)
                                
      
- ------------------------------------------------------------------------------
      
 6)   Citizenship or Place of Organization       Delaware
     
- ------------------------------------------------------------------------------
                          
                     7) Sole Voting Power        196,865,790/1/   71.0%/2/
     NUMBER OF            
                             
      SHARES       -----------------------------------------------------------
                          
   BENEFICIALLY      8) Shared Voting Power      0 
                          
     OWNED BY                    
                   -----------------------------------------------------------
       EACH             
                     9) Sole Dispositive Power   196,865,790/1/   71.0%/2/
    REPORTING             
                         
      PERSON       -----------------------------------------------------------
                          
       WITH         10) Shared Dispositive Power 0   
                                 
- ------------------------------------------------------------------------------
      
11)   Aggregate Amount Beneficially              196,865,790/1/   71.0%/2/
      owned by Each Reporting Person
      as of May 3, 1995 

- ------------------------------------------------------------------------------

12)   Check Box if the Aggregate Amount          [_]                        
      in Row (11) Excludes Certain Shares
                     
- ------------------------------------------------------------------------------

13)   Percent of Class Represented by            71.0%/2/
      Amount in Row (11) as of 
      May 3, 1995 

- ------------------------------------------------------------------------------

14)   Type of Reporting Person                   CO
      
- ------------------------------------------------------------------------------




                                 Page 4 of 11
<PAGE>
 



FOOTNOTES TO PRECEDING COVER PAGES:


1.  The Dow Chemical Company ("Dow"), directly and through its wholly owned
    subsidiaries RH Acquisition Corp. ("Acquisition") and Dow Holdings Inc.
    ("Dow Holdings"), holds 196,865,790 shares of the Issuer's common stock,
    par value $.10 per share.

2.  Dow's, Acquisition's and Dow Holdings' combined percentage ownership
    of the Issuer's common stock is 71.0%, based on the number of shares of
    the Issuer's common stock outstanding on April 28, 1995, as advised by
    the Issuer.



                                 Page 5 of 11
<PAGE>




This Amendment No. 20 amends the Statement of Schedule 13D filed by The Dow
Chemical Company ("TOCC"), RH Acquisition Corp. ("Acquisition") and Dow Holdings
Inc. ("Dow Holdings") with the Securities and Exchange Commission on
February 28, 1995, as previously amended (the "Schedule 13D"). This amendment
is being filed to reflect a press release issued on May 4, 1995 and as further
discussed in Items 4 and 6, below.

Item 4. Purpose of Transaction

Item 4 of the Schedule 13D is hereby amended and supplemented by adding the 
following:

     TOCC issued a press release on May 4, 1995, the text of which is as
     follows:

     
     May 4, 1995

     HOECHST AGREES TO ACQUIRE MARION MERRELL DOW

     The Dow Chemical Company, Hoechst and Marion Merrell Dow today signed
     the agreements under which Hoechst will acquire all of Marion Merrell
     Dow for $25.75 per share or about $7.1 billion.

     As part of the agreements, Hoechst will acquire approximately 197 million
     Marion Merrell Dow shares held by Dow for about $5.1 billion. The closing
     is expected to take place within 90 days, subject to government regulatory
     approvals. If closed, the transaction will result in a gain for Dow in a
     range of 35 to 50 cents per share.

     "The sale of Dow's interest in Marion Merrell Dow is consistent with our
     long-term strategy as the fit of pharmaceuticals into Dow's portfolio has
     diminished," said Frank Popoff, Dow chairman and chief executive officer.
     "This transaction will serve our shareholders well by liberating resources
     for our core business."   




                                 Page 6 of 11
<PAGE>
 
ITEM. 6  CONTRACTS, AGREEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO
         SECURITIES OF THE ISSUER.

Item 6 of the Schedule 13D is hereby amended and supplemented by adding the 
following:

     Agreement and Plan of Merger.  On May 3, 1995, Marion Merrell Dow Inc. (the
"Company"), TDCC, Hoechst Corporation ("Hoechst") and H Pharma Acquisition Corp.
("Acquisition") entered into an Agreement and Plan of Merger (the "Merger
Agreement") whereby Acquisition, a wholly-owned subsidiary of Hoechst, will be
merged with and into the Company, with the Company to continue as the surviving
corporation (the "Merger").  In the Merger, each issued and outstanding share of
the Company's common stock, par value $0.10 per share, (the "Shares") will be
converted into the right to receive $25.75 in cash.  In addition, if the Shares
held by TDCC or its affiliates (the "Dow Shares") are purchased by Hoechst,
Acquisition or their affiliates at least one day prior to the effective date of
the Merger (the "Effective Date"), each remaining shareholder will be entitled
to receive an additional amount equal to $0.25 multiplied by a fraction (i) the
numerator of which is the number of whole days from the record date for the
regular quarterly cash dividend next preceding the Effective Date (excluding
such record date but including the Effective Date), and (ii) the denominator of
which is the number of whole days in the full quarter in which the Effective
Date occurs.  Under the Merger Agreement, the Company is permitted to pay a
regular quarterly dividend of up to $0.25 per share, provided that the record
date for determining the holders of Shares entitled to receive such regular
quarterly cash dividends shall be the close of business on the last business day
of each calendar quarter.

     Consummation of the Merger is conditioned upon, among other things, (i)
approval by the stockholders of the Company, (ii) the termination or expiration
of any applicable waiting period under the Hart-Scott-Rodino Antitrust
Improvements Act of 1976, as amended (the "HSR Act"), Regulation (EEC) No.
4064/89 of the European Community (the "EC Merger Regulation") and the Canadian
Competition Act, and (iii) the purchase of the Dow Shares by Hoechst,
Acquisition or their affiliates.

     The Merger Agreement may be terminated and the Merger may be abandoned at
any time prior to the effective time of the Merger, among other things, (i) by
the mutual consent of Hoechst, Acquisition, TDCC and the Company, (ii) by
Hoechst, TDCC or the Company at any time after January 31, 1996, but only if
Hoechst, Acquisition or their affiliates have not yet purchased the Dow Shares,
or (iii) by TDCC if Acquisition fails to purchase the Dow Shares in violation of
Acquisition's obligations under the Stock Purchase Agreement.

                                 Page 7 of 11
<PAGE>
 
     Stock Purchase Agreement.  On May 3, 1995, Hoechst, Acquisition, TDCC, and
two wholly-owned subsidiaries of TDCC (together with TDCC, the "Sellers")
entered into a Stock Purchase Agreement (the "Stock Purchase Agreement")
pursuant to which Acquisition agreed to purchase, and the Sellers agreed to
sell, all of the Dow Shares at a purchase price of $25.75 per Share in cash.
The closing of such purchase and sale (the "Closing") shall take place on a
business day to be designated by Acquisition, but in no event later than three
days after the satisfaction of all conditions to the Stock Purchase Agreement,
provided, however, that the Closing may not take place during any period
beginning the date after a New York Stock Exchange "ex-dividend" date and ending
on the corresponding record date with respect to a regular quarterly dividend.
If the Dow Shares are acquired on or before a New York Stock Exchange "ex-
dividend" date in respect of any regular quarterly cash dividend on the Shares,
the dividend payable on the corresponding record date will be for the account of
Acquisition and not the Sellers.

     The Sellers have agreed to vote their respective Dow Shares in favor of
adoption of the Merger Agreement and against any action or agreement that would
result in a breach in any material respect of any terms of the Merger Agreement
or the Stock Purchase Agreement and against any action or agreement which would
impede, interfere with or discourage the transactions contemplated by the Merger
Agreement.  Upon receipt of the purchase price, each Seller has agreed to grant
Acquisition an irrevocable proxy to vote their respective Dow Shares.

     The obligation of Acquisition to purchase the Dow Shares is subject to,
among other things, (i) the termination or expiration of any applicable waiting
period under the HSR Act, the EC Merger Regulation and the Canadian Competition
Act, (ii) the Committee on Foreign Investment in the United States having
determined not to investigate the transactions under Section 721 of the Defense
Production Act of 1950, as amended ("Exon-Florio") or if such Committee shall
have determined to investigate the transactions, such investigation shall have
been completed or the President of the United States shall have determined (by
action or inaction) not to take any action under Exon-Florio, (iii) the absence
of any governmental action (such as the declaration of a banking moratorium or a
prohibition on the export of funds) which prevents Hoechst and Acquisition from
obtaining the funds necessary to pay the aggregate purchase price for the Dow
Shares, (iv) the accuracy in all material respects of the representations and
warranties of the Company set forth in the Merger Agreement and of TDCC in both
the Merger and Stock Purchase Agreements, except for such inaccuracies in the
representations and warranties of the Company that would not have a Material
Adverse Effect (as such term is defined in the Merger Agreement) and (v) the
performance in all material respects of the covenants and

                                 Page 8 of 11
<PAGE>
 
agreements of the Company in the Merger Agreement and of TDCC in both the Merger
and Stock Purchase Agreements, except for failures to perform of such covenants
and agreements by the Company that would not have a Material Adverse Effect.

     The Stock Purchase Agreement may be terminated at any time by mutual
written consent of the parties or upon termination of the Merger Agreement.

     Other Agreements.  In connection with the transactions contemplated by the
Merger Agreement and the Stock Purchase Agreement, the following additional
agreements respecting the Company were executed on May 3, 1995.

     Pursuant to an Indemnity Agreement, Hoechst agreed to indemnify TDCC in
     respect of TDCC's existing guaranty in favor of the investors in
     Carderm Capital L.P., in which subsidiaries of the Company hold a
     controlling interest.  Pursuant to a Tax Allocation Agreement, TDCC,
     Hoechst and the Company agreed to an allocation of certain tax
     liabilities.  Pursuant to separate Computerized Process Control
     Software Agreements, affiliates of TDCC and affiliates of the Company
     agreed to leases of certain process control software owned by
     affiliates of TDCC.  Pursuant to an Insurance Separation Agreement,
     Hoechst, the Company, TDCC and three wholly-owned insurance
     subsidiaries  of TDCC agreed to certain matters regarding insurance,
     reinsurance and related topics.  Pursuant to a Manufacturing Agreement
     Amendment between TDCC, the Company and Merrell Dow Pharmaceuticals,
     Inc., a wholly owned subsidiary of MMD ("MDPI"), the terms of a
     manufacturing arrangement and ground lease relating to a manufacturing
     facility in Midland, Michigan were modified and TDCC agreed to
     repurchase the facility upon the termination of the manufacturing
     arrangement at a purchase price of 60% of the residual book value of
     the facility at the time of termination.  Pursuant to a Second
     Amendment to Master Service Agreement between TDCC, the Company and
     MDPI, certain research and development services provided by TDCC were
     modified and TDCC agreed to purchase certain physical assets owned by
     either MMD or MDPI upon the termination of the research services
     arrangements at a purchase price of 60% of the residual book value of
     the assets at the time of termination of the research services
     arrangements.  Pursuant to a Third Amendment to Master Services
     Agreement between TDCC, the Company and MDPI, certain services
     provided globally by TDCC to subsidiaries of the Company were
     terminated and certain other services provided by TDCC to specific
     subsidiaries of the Company were extended under similar terms to
     existing agreements.  Pursuant to two letter agreements entered into
     by TDCC and the Company, the parties set forth (i) a non-exclusive
     list of agreements to be reached prior to the date of the purchase of
     Dow Shares and (ii) certain agreements regarding employment matters in
     Italy.

                                 Page 9 of 11
<PAGE>
 
ITEM. 7  MATERIAL TO BE FILED AS EXHIBITS

(a)  Agreement and Plan of Merger.

(b)  Stock Purchase Agreement.

(c)  Indemnity Agreement, dated as of May 3, 1995, between Hoechst Corporation
     and The Dow Chemical Company.

(d)  Tax Allocation Agreement, dated as of May 3, 1995, among The Dow Chemical
     Company, Hoechst Corporation and Marion Merrell Dow Inc.

(e)  Computerized Process Control Software Agreement (Leases and Services),
     dated as of May 3, 1995, between Rofan Services, Inc. and Marion Merrell
     Pharmaceuticals, Inc.

(f)  Computerized Process Control Software Agreement (Leases and Services),
     dated as of May 3, 1995, between Rofan Automation and Information Systems
     B.V. and Gruppo Lepetit S.p.A.

(g)  Computerized Process Control Software Agreement (Leases and Services),
     dated as of May 3, 1995, between Rofan Automation and Information Systems
     B.V. and Biochimica Del Salento S.p.A.

(h)  Insurance Separation Agreement, dated as of May 3, 1995, among The Dow
     Chemical Company, Hoechst Corporation, Marion Merrell Dow Inc., Dorinco
     Insurance Company, Dorintal Reinsurance Ltd. and Timber Insurance Ltd.

(i)  Manufacturing Agreement Amendment, dated as of May 3, 1995, between The Dow
     Chemical Company and Marion Merrell Pharmaceuticals, Inc.

(j)  Second Amendment to Master Services Agreements, dated as of May 3, 1995,
     between Marion Merrell Dow Inc., The Dow Chemical Company and Marion
     Merrell Pharmaceuticals, Inc.

(k)  Third Amendment to Master Services Agreements, dated as of May 3, 1995,
     between Marion Merrell Dow Inc., The Dow Chemical Company and Marion
     Merrell Pharmaceuticals, Inc.

(l)  Letter Agreement, dated as of May 3, 1995, between The Dow Chemical Company
     and Marion Merrell Dow Inc.

(n)  Letter Agreement, dated as of May 3, 1995, among The Dow Chemical Company,
     Marion Merrell Pharmaceuticals, Inc. and Marion Merrell Dow Inc.

                                 Page 10 of 11
<PAGE>
 




                                   SIGNATURE


After due inquiry and to the best of my knowledge and belief, I certify that
the information set forth in this statement is true, complete and correct.


Dated: May 4, 1995                THE DOW CHEMICAL COMPANY



                                  By: /s/ William S. Stavropoulos
                                     ----------------------------------------
                                  Name:   William S. Stavropoulos
                                  Title:  President & Chief Operating Officer



 
                                   SIGNATURE


After due inquiry and to the best of my knowledge and belief, I certify that
the information set forth in this statement is true, complete and correct.


Dated: May 4, 1995                RH ACQUISITION CORP.           



                                  By: /s/ John C. Lillich         
                                     ----------------------------------------
                                  Name:   John C. Lillich           
                                  Title:  President & Chief Executive Officer




                                   SIGNATURE


After due inquiry and to the best of my knowledge and belief, I certify that
the information set forth in this statement is true, complete and correct.


Dated: May 4, 1995                DOW HOLDINGS INC.          



                                  By: /s/ Henry Kahn              
                                     ----------------------------------------
                                  Name:   Henry Kahn                   
                                  Title:  Treasurer                            




                                 Page 11 of 11


<PAGE>
 
                          AGREEMENT AND PLAN OF MERGER

          THIS AGREEMENT AND PLAN OF MERGER, dated as of May 3, 1995, is by and
among Marion Merrell Dow Inc., a Delaware corporation (the "Company"), The Dow
Chemical Company, a Delaware corporation ("DCC"), Hoechst Corporation, a
Delaware corporation ("Parent"), and H Pharma Acquisition Corp., a Delaware
corporation ("Acquisition").

          WHEREAS, the Boards of Directors of Parent, Acquisition, DCC and the
Company have each approved the acquisition of the Company by Parent upon the
terms and subject to the conditions set forth in this Agreement;

          WHEREAS, in furtherance thereof, upon the terms and subject to the
conditions of this Agreement, (i) Acquisition would be merged (the "Merger")
with and into the Company in accordance with the General Corporation Law of the
State of Delaware ("Delaware Law") and (ii) each share of common stock, par
value $0.10 per share, of the Company (the "Shares"), issued and outstanding
immediately prior to the Effective Time (as defined herein) would, except as
otherwise expressly provided herein, be converted into the right to receive the
Merger Consideration (as defined herein); and

          WHEREAS, simultaneously with the execution and delivery hereof,
Parent, Acquisition, DCC, RH Acquisition Corp., a Delaware corporation and a
wholly owned subsidiary of DCC ("RHAC"), and Dow Holdings Inc., a Delaware
corporation and a wholly owned subsidiary of DCC ("DHI" and, collectively with
DCC and RHAC, "Dow") are entering into a stock purchase agreement (the "Stock
Purchase Agreement") pursuant to which Dow has agreed, among other things, to
sell to Acquisition all of the 196,865,790 Shares held by Dow (the "Dow
Shares").

          NOW, THEREFORE, in consideration of the foregoing and the mutual
covenants and agreements herein contained, and intending to be legally bound
hereby, the Company, DCC, Parent and Acquisition hereby agree as follows.

<PAGE>
 
                                   ARTICLE I

                                   THE MERGER

          Section 1.1  The Merger.  At the Effective Time and upon the terms and
subject to the conditions of this Agreement and Delaware Law, Acquisition shall
be merged with and into the Company, whereupon the separate corporate existence
of Acquisition shall cease and the Company shall continue as the surviving
corporation (the "Surviving Corporation").  At Acquisition's option, subject to
Section 9.2 hereof, the Merger may be structured so that any direct subsidiary
of Parent other than Acquisition is merged with and into the Company.  In the
event of such election, the parties agree to execute an appropriate amendment to
this Agreement in order to reflect such election.

          Section 1.2  Effective Time; Closing.  As soon as practicable after
the satisfaction or waiver of the conditions set forth in Article VII, the
parties hereto will file a certificate of merger with the Secretary of State of
the State of Delaware and make all other filings or recordings required by
Delaware Law in connection with the Merger.  The Merger shall become effective
at such time as the certificate of merger is duly filed with the Secretary of
State of the State of Delaware (the "Effective Time").  Prior to such filing, a
closing (the "Closing") shall be held at the offices of Skadden, Arps, Slate,
Meagher & Flom, 919 Third Avenue, New York, New York 10022, or such other place
as the parties shall agree, for the purpose of confirming the satisfaction or
waiver of the conditions set forth in Article VII.  The date on which the
Closing occurs is referred to herein as the "Closing Date".

          Section 1.3  Effects of the Merger; Subsequent Actions.  (a) The
Merger shall have the effects set forth in Delaware Law.  Without limiting the
generality of the foregoing, and subject thereto and any other applicable laws,
at the Effective Time, all the properties, rights, privileges, powers and
franchises of the Company and Acquisition shall vest in the Surviving
Corporation, and all debts, liabilities, restrictions, disabilities and duties
of the Company and Acquisition shall become the debts, liabilities,
restrictions, disabilities and duties of the Surviving Corporation.

                                       2

<PAGE>
 
          (b)  If, at any time after the Effective Time, the Surviving
Corporation shall consider or be advised that any deeds, bills of sale,
assignments, assurances or any other actions or things are necessary or
desirable to vest, perfect or confirm of record or otherwise in the Surviving
Corporation its right, title or interest in, to or under any of the rights,
properties or assets of the Company or Acquisition acquired or to be acquired by
the Surviving Corporation as a result of or in connection with the Merger, or
otherwise to carry out this Agreement, the officers and directors of the
Surviving Corporation shall be authorized to execute and deliver, in the name
and on behalf of the Company or Acquisition, all such deeds, bills of sale,
assignments, assumption agreements and assurances and to take and do, in the
name and on behalf of each of such corporations or otherwise, all such other
actions and things as may be necessary or desirable to vest, perfect or confirm
any and all right, title and interest in, to and under such rights, properties
or assets of the Surviving Corporation or otherwise to carry out this Agreement.

          Section 1.4  Certificate of Incorporation and By-Laws.  (a) The
Certificate of Incorporation of Acquisition in effect immediately prior to the
Effective Time shall be the Certificate of Incorporation of the Surviving
Corporation until amended in accordance with applicable law; provided that the
name of the Surviving Corporation as set forth in its Certificate of
Incorporation shall be changed to a new name to be determined by Acquisition
prior to the Effective Time.

          (b)  The By-Laws of Acquisition in effect at the Effective Time shall
be the By-Laws of the Surviving Corporation until amended in accordance with
applicable law.

          Section 1.5  Directors.  The directors of Acquisition at the Effective
Time shall be the initial directors of the Surviving Corporation, each to hold
office in accordance with the Certificate of Incorporation and By-Laws of the
Surviving Corporation and until his or her successor is duly elected and
qualified.

          Section 1.6  Officers.  The officers of the Company at the Effective
Time, and any additional individuals designated by Parent, shall be the initial
offi-

                                       3

<PAGE>
 
cers of the Surviving Corporation, each to hold office in accordance with the
Certificate of Incorporation and By-Laws of the Surviving Corporation and until
his or her successor is duly appointed and qualified.

          Section 1.7  Conversion of Shares.  At the Effective Time, by virtue
of the Merger and without any action on the part of Parent, Acquisition, the
Company or the holder of any of the following securities:

          (a)  Each Share issued and outstanding immediately prior to the
Effective Time (other than Shares to be cancelled pursuant to Section 1.7(b)
hereof and Dissenting Shares (as hereinafter defined)), shall by virtue of the
Merger and without any action on the part of the holder thereof be converted
into the right to receive the Merger Consideration (as defined below), without
interest thereon.  As used herein, "Merger Consideration" means the sum (rounded
up to the nearest $0.01) of $25.75 in cash plus an Additional Contingent Amount
(as defined below); provided, that the Additional Contingent Amount shall be
payable only if Acquisition, Parent or their affiliates purchase the Dow Shares
at least one (1) day prior to the Effective Time.  As used herein, "Additional
Contingent Amount" means a cash amount equal to $0.25 multiplied by a fraction
(i) the numerator of which shall be the number of whole days from the record
date for the regular quarterly cash dividend on the Shares next preceding the
date on which the Effective Time occurs (excluding such record date) to and
including the date on which the Effective Time occurs and (ii) the denominator
of which shall be the number of whole days in the full quarter during which the
Effective Time occurs.

          (b)  Each Share which is issued and outstanding immediately prior to
the Effective Time and owned by Parent or Acquisition or any direct or indirect
subsidiary of Parent or Acquisition, or which is held in the treasury of the
Company or any of its subsidiaries, shall be cancelled and retired and no
payment of any consideration shall be made with respect thereto.

          (c)  Each share of Common Stock, par value $0.01 per share, of
Acquisition issued and outstanding immediately prior to the Effective Time shall
be converted into and become one validly issued, fully paid and

                                       4

<PAGE>
 
nonassessable share of Common Stock, par value $0.01 per share, of the Surviving
Corporation.

          Section 1.8  Company Plans.  (a) Effective as of the Effective Time,
each outstanding option (including any related stock appreciation right)(an
"Employee Option") issued, awarded or granted pursuant to the Company's 1992
Incentive Compensation Plan, the 1985 Associate Stock Option Plan or the Non-
Qualified Employee Stock Option Plan (the "Company Plans") to purchase Shares
shall be eliminated by the Company, and each holder of an eliminated Employee
Option shall be entitled to receive from the Company (or, at Parent's option,
any subsidiary of the Company) in consideration for the elimination of such
Employee Option an amount in cash (less applicable withholding Taxes (as defined
in Section 3.10 hereof)) equal to the product of (i) the number of Shares
previously subject to such Employee Option and (ii) the excess, if any, of the
Merger Consideration over the exercise price per Share previously subject to
such Employee Option; provided, that each Employee Option the exercise price per
Share of which is equal to or greater than the Merger Consideration shall be
eliminated in consideration for a cash payment equal to the product of $0.01
multiplied by the number of Shares previously subject to such Employee Option.

          (b)  Each outstanding performance share ("Performance Share") granted
under the Company's 1992 Incentive Compensation Plan (the "Incentive Plan")
shall become fully vested in accordance with the terms of the Incentive Plan
and, effective as of the Effective Time, shall, unless theretofore paid and
eliminated in accordance with the terms thereof, be eliminated by the Company,
and each holder of an eliminated Performance Share shall be entitled to receive
from the Company (or, at Parent's option, any subsidiary of the Company) an
amount in cash (less applicable withholding Taxes) equal to the product of (i)
the Merger Consideration and (ii) the number of Performance Shares previously
held by such holder.

          Section 1.9  Stockholders' Meeting.  The Company, acting through its
Board of Directors (the "Board"), shall in accordance with applicable law as
soon as practicable following the date hereof:

                                       5

<PAGE>
 
               (i)  subject to applicable law, duly call, give notice of,
     convene and hold an annual or special meeting of its stockholders (the
     "Stockholders' Meeting") for the purpose of considering and taking action
     upon this Agreement;

               (ii)  subject to the fiduciary duties of the Board under
     applicable law, include in the Proxy Statement (as defined in Section 3.7)
     the recommendation of the Board that stockholders of the Company vote in
     favor of adoption of this Agreement and the transactions contemplated
     hereby; and

               (iii)  subject to the fiduciary duties of the Board under
     applicable law, use its reasonable best efforts to obtain the necessary
     approvals by its stockholders of this Agreement and the transactions
     contemplated hereby.

          At such meeting, each of DCC, Parent and Acquisition will vote (and
will cause each of their respective affiliates to vote) all Shares owned by it
(or their respective affiliates) in favor of adoption of this Agreement and the
transactions contemplated hereby.


                                   ARTICLE II

                     DISSENTING SHARES; EXCHANGE OF SHARES

          Section 2.1  Dissenting Shares.  Notwithstanding anything in this
Agreement to the contrary, Shares outstanding immediately prior to the Effective
Time and held by a holder who has not voted in favor of the Merger or consented
thereto in writing and who has demanded appraisal for such Shares in accordance
with Section 262 of Delaware Law ("Dissenting Shares") shall not be converted
into a right to receive the Merger Consideration unless such holder fails to
perfect or withdraws or otherwise loses his right to appraisal.  If, after the
Effective Time, such holder fails to perfect or withdraws or loses his right to
appraisal, such Shares shall be treated as if they had been converted as of the
Effective Time into a right to receive the Merger Consideration

                                       6

<PAGE>
 
without interest thereon.  The Company shall give Acquisition prompt notice of
any demands received by the Company for appraisal of Shares, and, prior to the
Effective Time, Acquisition shall have the right to participate in all
negotiations and proceedings with respect to such demands.  Prior to the
Effective Time, the Company shall not, except with the prior written consent of
Acquisition, make any payment with respect to, or settle or offer to settle, any
such demands.

          Section 2.2  Exchange of Certificates.  

          (a) Prior to the Effective Time, Parent shall designate a bank or 
trust company reasonably acceptable to the Company to act as paying agent (the
"Paying Agent") in effecting the exchange for the Merger Consideration of
certificates (the "Certificates") that, prior to the Effective Time, represented
Shares. Upon the surrender of each such Certificate formerly representing
Shares, together with a properly completed letter of transmittal, the Paying
Agent shall pay the holder of such Certificate the Merger Consideration
multiplied by the number of Shares formerly represented by such Certificate, in
exchange therefor, and such Certificate shall forthwith be cancelled. Until so
surrendered and exchanged, each such Certificate (other than Certificates
representing Dissenting Shares or Shares held by Parent, Acquisition or the
Company, or any direct or indirect subsidiary thereof) shall represent solely
the right to receive the Merger Consideration. No interest shall be paid or
accrue on the Merger Consideration. If the Merger Consideration (or any portion
thereof) is to be delivered to any person other than the person in whose name
the Certificate formerly representing Shares surrendered in exchange therefor is
registered, it shall be a condition to such exchange that the Certificate so
surrendered shall be properly endorsed or otherwise be in proper form for
transfer and that the person requesting such exchange shall pay to the Paying
Agent any transfer or other Taxes required by reason of the payment of the
Merger Consideration to a person other than the registered holder of the
Certificate surrendered, or shall establish to the satisfaction of the Paying
Agent that such Tax has been paid or is not applicable.

          (b)  Prior to the Effective Time, Parent or Acquisition shall deposit,
or cause to be deposited, in trust with the Paying Agent the Merger
Consideration

                                       7

<PAGE>
 
to which holders of Shares shall be entitled at the Effective Time pursuant to
Section 1.7(a) hereof; provided that no such deposit shall relieve Parent of its
obligation to pay the Merger Consideration pursuant to Section 1.7(a).

          (c)  The Merger Consideration shall be invested by the Paying Agent,
as directed by Parent, provided such investments shall be limited to direct
obligations of the United States of America, obligations for which the full
faith and credit of the United States of America is pledged to provide for the
payment of principal and interest, commercial paper rated of the highest quality
by Moody's Investors Services, Inc. or Standard & Poor's Corporation, or
certificates of deposit issued by a commercial bank having at least
$1,000,000,000 in assets; provided, that no loss on investment made pursuant to
this Section 2.2(c) shall relieve Parent or Acquisition of its obligation to pay
the Merger Consideration pursuant to Section 1.7(a).

          (d)  Promptly following the date which is six months after the
Effective Time, the Paying Agent shall deliver to Parent all cash and documents
in its possession relating to the transactions described in this Agreement, and
the Paying Agent's duties shall terminate.  Thereafter, each holder of a
Certificate formerly representing a Share may surrender such Certificate to the
Surviving Corporation and (subject to applicable abandoned property, escheat and
similar laws) receive in exchange therefor the Merger Consideration, without any
interest thereon.

          (e)  Promptly after the Effective Time, the Paying Agent shall mail to
each record holder of Certificates that immediately prior to the Effective Time
represented Shares a form of letter of transmittal and instructions for use in
surrendering such Certificates and receiving the Merger Consideration in
exchange therefor.

          (f)  After the Effective Time, there shall be no transfers on the
stock transfer books of the Surviving Corporation of any Shares.  If, after the
Effective Time, Certificates formerly representing Shares are presented to the
Surviving Corporation or the Paying Agent, they shall be cancelled and exchanged
for the

                                       8

<PAGE>
 
Merger Consideration, as provided in this Article II, subject to applicable law
in the case of Dissenting Shares.


                                  ARTICLE III

                 REPRESENTATIONS AND WARRANTIES OF THE COMPANY

          The Company represents and warrants to Parent and Acquisition as
follows:

          Section 3.1  Organization and Qualification; Subsidiaries.  (a)  Each
of the Company and its subsidiaries is a corporation duly organized, validly
existing and in good standing under the laws of the jurisdiction of its
incorporation and has all requisite corporate power and authority to own, lease
and operate its properties and to carry on its business as now being conducted,
except where the failure to be so organized, existing and in good standing or to
have such power and authority would not, individually or in the aggregate, have
a material adverse effect on the business, results of operations (on an
annualized basis) or financial condition of the Company and its subsidiaries,
taken as a whole (a "Material Adverse Effect").  Without limiting the generality
of the foregoing definition of "Material Adverse Effect", such definition shall
specifically include adverse consequences to earnings or financial condition in
excess of $75 million to the Company and its subsidiaries, taken as a whole, but
shall specifically exclude adverse consequences to earnings and financial
condition of $75 million or less unless such adverse consequences also
constitute a material adverse effect on the business, results of operations (on
an annualized basis) or financial condition of the Company and its subsidiaries,
taken as a whole.  "Material Adverse Effect" shall not mean or include any of
the events set forth on Schedule 3.1(a) or any of the transactions effected
pursuant to this Agreement.

          (b)  Each of the Company and its subsidiaries is duly qualified or
licensed and in good standing to do business in each jurisdiction (including any
foreign country) in which the property owned, leased or operated by it or the
nature of the business conducted by it makes such qualification or licensing
necessary,

                                       9

<PAGE>
 
except where the failure to be so duly qualified or licensed and in good
standing would not, individually or in the aggregate, have a Material Adverse
Effect.

          (c)  The Company has heretofore furnished or made available to Parent
complete and correct copies of the Company's Restated Certificate of
Incorporation and By-Laws and the equivalent organizational documents of each of
its subsidiaries, each as amended to the date hereof, as requested by Parent.
Such Restated Certificate of Incorporation, By-Laws and equivalent
organizational documents are in full force and effect.  The Company is not in
violation of any of the provisions of its Restated Certificate of Incorporation
or By-Laws and no subsidiary of the Company is in violation of any of the
provisions of such subsidiary's equivalent organizational documents.

          (d)  The Company has heretofore furnished or made available to Parent
a complete and correct list of the subsidiaries of the Company, which list sets
forth the amount of capital stock of or other equity interests in such
subsidiaries owned by the Company, directly or indirectly.  Except as set forth
in Schedule 3.1(d), no entity in which the Company owns, directly or indirectly,
less than a 50% equity interest is, individually or when taken together with all
other such entities, material to the business of the Company and its
subsidiaries, taken as a whole.

          Section 3.2  Capitalization of the Company and its Subsidiaries.  The
authorized capital stock of the Company consists of (i) 350,000,000 Shares of
which, as of April 28, 1995, 277,097,048 Shares were issued and outstanding
(including 1,992,600 Shares subject to restrictions issued pursuant to employee
benefit plans of the Company and its subsidiaries or otherwise) and (ii)
8,000,000 shares of Preferred Stock, par value $1.00 per share, of which, as of
April 28, 1995, 2,769,670 shares of Series A ESOP Convertible Preferred Stock
(the "Series A Preferred Shares") were issued and outstanding.  All outstanding
shares of capital stock of the Company have been validly issued, and are fully
paid, nonassessable and free of preemptive rights.  As of April 28, 1995,
Employee Options to purchase an aggregate of 22,213,415 Shares were outstanding
and the weighted average exercise price of such Employee Options was $22.86 per
Share.  As

                                      10

<PAGE>
 



of April 28, 1995, 2,769,670 Shares were reserved for issuance upon conversion
of the Series A Preferred Shares.  Each Series A Preferred Share is convertible
into one Share.  Except as set forth above or in Schedule 3.2, and except as a
result of the exercise of Employee Options outstanding as of April 28, 1995,
there are outstanding (i) no shares of capital stock or other voting securities
of the Company, (ii) no securities of the Company convertible into or
exchangeable for shares of capital stock or voting securities of the Company,
(iii) no options, subscriptions, warrants, convertible securities, calls or
other rights to acquire from the Company, and no obligation of the Company to
issue, deliver or sell any capital stock, voting securities or securities
convertible into or exchangeable for capital stock or voting securities of the
Company and (iv) no equity equivalents, performance shares, interests in the
ownership or earnings of the Company or other similar rights issued by the
Company (collectively, "Company Securities").  Except as set forth on Schedule
3.2 or as contemplated by this Agreement, there are no outstanding obligations
of the Company or any of its subsidiaries to repurchase, redeem or otherwise
acquire any Company Securities, other than the Company's obligations hereunder
and under the Restated Certificate of Incorporation of the Company to redeem the
Series A Preferred Shares.  Except as set forth in Schedule 3.2, each of the
outstanding shares of capital stock of each of the Company's subsidiaries is
duly authorized, validly issued, fully paid and nonassessable and is directly or
indirectly owned by the Company, free and clear of all security interests,
liens, claims, pledges, charges, voting agreements or other encumbrances of any
nature whatsoever (collectively, "Liens").  Except as set forth in Schedule 3.2,
there are no existing options, calls or commitments of any character relating to
the issued or unissued capital stock or other equity securities of any
subsidiary of the Company.

          Section 3.3  Authority Relative to this Agreement; Fairness Opinion.
The Company has all necessary corporate power and authority to execute and
deliver this Agreement, to perform its obligations hereunder and to consummate
the transactions contemplated hereby.  The Board, at a meeting duly called and
held on May 3, 1995,  (i) determined that this Agreement and the transactions
contemplated hereby, including the Merger, are in the




                                      11
<PAGE>
 



best interests of the stockholders of the Company (other than DCC, Parent,
Acquisition or their affiliates), (ii) approved this Agreement and the
transactions contemplated hereby, including the Merger, (iii) resolved, subject
to their fiduciary duties under applicable law, to recommend that the
stockholders of the Company approve and adopt this Agreement and the Merger and
(iv) resolved to redeem, effective immediately prior to the Merger, all of the
outstanding Series A Preferred Shares.  Lehman Brothers Inc. ("Lehman Brothers")
has delivered to the Board its written opinion dated May 3, 1995 to the effect
that, as of the date of such opinion, the consideration to be received by the
holders of Shares (other than DCC, Parent, Acquisition or their affiliates)
pursuant to the Merger is fair to such holders from a financial point of view.
As of the date hereof, the Company has been authorized by Lehman Brothers to
permit the inclusion of such fairness opinion in the Proxy Statement referred to
in Section 3.7.  The execution, delivery and performance of this Agreement and
the consummation of the transactions contemplated hereby have been duly and
validly authorized by the Board and no other corporate proceedings on the part
of the Company are necessary to authorize this Agreement or to consummate the
transactions so contemplated (other than, with respect to the Merger, the
approval and adoption of this Agreement by the holders of a majority of the
outstanding Shares and Series A Preferred Shares (voting together as a single
class) and the filing of the appropriate merger documents as required by
Delaware Law).  The Board has taken all action necessary with respect to the
transactions contemplated hereby and by the Stock Purchase Agreement so as to
render inapplicable to such transactions, including, without limitation, the
Merger and the purchase of Shares pursuant to the Stock Purchase Agreement, the
restrictions on business combinations contained in Section 203 of the Delaware
Law and the supermajority voting requirements contained in Article Fifteenth of
the Company's Restated Certificate of Incorporation.  This Agreement has been
duly and validly executed and delivered by the Company and, assuming it
constitutes a valid and binding agreement of the other parties hereto,
constitutes a legal, valid and binding agreement of the Company enforceable
against the Company in accordance with its terms.

          Section 3.4  Non-Contravention; Required Filings and Consents.  
(a) Except as set forth in Schedule




                                      12
<PAGE>
 



3.4, the execution, delivery and performance by the Company of this Agreement
and the consummation of the transactions contemplated hereby (including the
Merger) do not and will not (i) contravene or conflict with the Restated
Certificate of Incorporation or By-Laws of the Company or the equivalent
organizational documents of any of its subsidiaries; (ii) assuming that all
consents, authorizations and approvals contemplated by subsection (b) below have
been obtained and all filings described therein have been made, contravene or
conflict with or constitute a violation of any provision of any law, regulation,
judgment, injunction, order or decree binding upon or applicable to the Company,
any of its subsidiaries or any of their respective properties; (iii) conflict
with, or result in the breach or termination of any provision of or constitute a
default (with or without the giving of notice or the lapse of time or both)
under, or give rise to any right of termination, cancellation, or loss of any
benefit to which the Company or any of its subsidiaries is entitled under any
provision of any agreement, contract, license or other instrument binding upon
the Company, any of its subsidiaries or any of their respective properties, or
allow the acceleration of the performance of, any obligation of the Company or
any of its subsidiaries under any indenture, mortgage, deed of trust, lease,
license, contract, instrument or other agreement to which the Company or any of
its subsidiaries is a party or by which the Company or any of its subsidiaries
or any of their respective assets or properties is subject or bound; or (iv)
result in the creation or imposition of any Lien on any asset of the Company or
any of its subsidiaries, except in the case of clauses (ii), (iii) and (iv) for
any such contraventions, conflicts, violations, breaches, terminations,
defaults, cancellations, losses, accelerations and Liens which would not
individually or in the aggregate have a Material Adverse Effect or be reasonably
expected to prevent the consummation by the Company of the transactions
contemplated by this Agreement.

          (b)  The execution, delivery and performance by the Company of this
Agreement and the consummation of the transactions contemplated hereby
(including the Merger) by the Company require no action by or in respect of, or
filing with, any governmental body, agency, official or authority (either
domestic or foreign) other than (i) the filing of a certificate of merger in
accor-




                                      13
<PAGE>
 



dance with Delaware Law; (ii) compliance with any applicable requirements of the
Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the "HSR
Act"), Regulation (EEC) No. 4064/89 of the European Community (the "EC Merger
Regulation"), and the Canadian Competition Act; (iii) the filing of a notice
pursuant to Section 721 of the Defense Production Act of 1950, as amended
("Exon-Florio"); (iv) compliance with any applicable requirements of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), and state
securities, takeover and Blue Sky laws; and (v) such actions or filings which,
if not taken or made, would not individually or in the aggregate have a Material
Adverse Effect or be reasonably expected to prevent the consummation by the
Company of the transactions contemplated by this Agreement.

          Section 3.5  SEC Reports.  (a) The Company has filed all required
forms, reports and documents with the Securities and Exchange Commission (the
"SEC") since January 1, 1992.  The Company has made available to Parent, in the
form filed with the SEC, the Company's (i) Annual Reports on Form 10-K for the
fiscal years ended December 31, 1994, 1993 and 1992, (ii) Quarterly Reports on
Form 10-Q for the quarters ended March 31, 1994, June 30, 1994 and September 30,
1994, (iii) all proxy statements relating to meetings of the Company's
stockholders since December 31, 1992 and (iv) all other reports or registration
statements (other than reports on Form 10-Q not referred to in (ii) above) filed
by the Company with the SEC since December 31, 1992 (collectively, the "SEC
Reports").  The SEC Reports were prepared in accordance with all applicable
requirements of the Securities Act of 1933, as amended (the "Securities Act"),
and the Exchange Act.  As of their respective dates, none of the SEC Reports,
including, without limitation, any financial statements or schedules included
therein, contained any untrue statement of a material fact or omitted to state a
material fact required to be stated therein or necessary in order to make the
statements therein, in light of the circumstances under which they were made,
not misleading.  The audited consolidated financial statements and unaudited
consolidated interim financial statements of the Company included in the SEC
Reports fairly present, in conformity with generally accepted accounting
principles applied on a consistent basis (except as may be indicated in the
notes thereto), the consolidated financial posi-




                                      14
<PAGE>
 



tion of the Company and its consolidated subsidiaries as of the dates thereof
and their consolidated results of operations and cash flows for the periods then
ended (subject to normal year-end adjustments and the lack of footnote
disclosure (to the extent permitted by SEC rules) in the case of any unaudited
interim financial statements and subject to any subsequent reclassification as
indicated in SEC Reports filed prior to the date hereof).  The Company has
heretofore provided or made available complete and correct copies of each of the
SEC Reports to Parent.

          (b)  Except as disclosed in the SEC Reports filed prior to the date of
this Agreement or as set forth in Schedule 3.5(b), the Company and its
subsidiaries have no liabilities of any nature (whether accrued, absolute,
contingent or otherwise), except for liabilities incurred in the ordinary course
of business since December 31, 1994 or liabilities which would not, individually
or in the aggregate, have a Material Adverse Effect.

          Section 3.6  Absence of Certain Changes; Net Cash Position;
Derivatives.  (a) Since December 31, 1994, except as disclosed in the SEC
Reports filed prior to the date of this Agreement or as set forth in Schedule
3.6(a), neither the Company nor any of its subsidiaries has (i) declared, set
aside or paid any dividend or other distribution (whether in cash, stock, or
property or any combination thereof) in respect of its capital stock (other than
cash dividends declared and paid on the Series A Preferred Shares in accordance
with their terms and on the Shares to holders of record on March 31, 1995 in the
amount of $0.25 per Share), (ii) entered into, adopted or amended or materially
increased the benefits paid or payable under any severance, termination or
deferred compensation agreement or arrangement with any director, officer or
employee, (iii) changed any of the accounting principles or practices used by
the Company, except as required as a result of a change in law, SEC guidelines
or generally accepted accounting principles, (iv) settled litigations for
amounts in excess of $3 million in the aggregate, or (v) except as previously
disclosed to Parent, entered into any transaction, or conducted its business or
operations, except in the ordinary course of business consistent with past
practice or where such transactions or conduct would not, individ-




                                      15
<PAGE>
 



ually or in the aggregate, have a Material Adverse Effect.  Since December 31,
1994, there has not been any material adverse change in the business, results of
operations (on an annualized basis) or financial condition of the Company and
its subsidiaries, taken as a whole.  For purposes of this Section 3.6(a),
"material adverse change" shall be construed without reference to the definition
of Material Adverse Effect and shall not mean or include any of the events set
forth in Schedule 3.1(a) or any of the transactions effected pursuant to this
Agreement.

          (b)  As of the date of this Agreement, subject to the last sentence of
this Section 3.6(b), the Net Cash of the Company and its subsidiaries is at
least $250 million.  As used herein, "Net Cash" means the excess of (i) the sum
of the cash, cash equivalents, short term investments, notes receivable
(excluding trade notes receivable) and long term readily marketable financial
assets of the Company and its subsidiaries over (ii) the sum of the accounts
payable to DCC and its affiliates (other than the Company and its subsidiaries),
dividends payable, notes payable (excluding trade notes payable), long term debt
(including current portion of long term debt) and any other balance sheet
liabilities for borrowed money of the Company and its subsidiaries, in each case
determined in conformity with generally accepted accounting principles.  The
accounts payable to DCC and its affiliates (other than the Company and its
subsidiaries) included in the $250 million Net Cash referred to above total $58
million and are as of March 31, 1995.

          (c)  Schedule 3.6(c) sets forth a complete and correct list of all
Derivative Financial Instruments (including the face, contract or notional
amount of and any open position relating to such Derivative Financial
Instruments and a brief summary of the nature and terms thereof) as of April 30,
1995 to which the Company or any of its subsidiaries is a party or by which the
Company or any of its subsidiaries or any of their respective assets or
properties is subject or bound (including, without limitation, funds of the
Company or any of its subsidiaries invested by any other person).  For purposes
of this Agreement, "Derivative Financial Instrument" means any futures, forward,
swap, option or swaption contract, or any other financial instrument with
similar characteris-




                                      16
<PAGE>
 



tics and/or generally characterized by the financial community as a "derivative"
security.

          Section 3.7  Proxy Statement; Schedule 13E-3.  The proxy or
information statement or similar materials distributed to the Company's
stockholders in connection with the Merger, including any amendments or
supplements thereto (the "Proxy Statement"), shall not, at the time filed with
the SEC, at the time mailed to the Company's stockholders, at the time of the
Stockholders' Meeting or at the Effective Time, contain any untrue statement of
a material fact or omit to state any material fact required to be stated therein
or necessary in order to make the statements therein, in light of the
circumstances under which they are made, not misleading.  Notwithstanding the
foregoing, the Company makes no representation or warranty with respect to any
information provided by Parent or Acquisition specifically for use in the Proxy
Statement.  The Proxy Statement will comply as to form in all material respects
with the provisions of the Exchange Act and the rules and regulations
thereunder.  None of the information provided by the Company specifically for
use in any Rule 13e-3 Transaction Statement on Schedule 13E-3 required to be
filed with the SEC under the Exchange Act in connection with the Merger (the
"Schedule 13E-3") will at the time the Schedule 13E-3 or any amendments thereto
are filed with the SEC, contain any untrue statement of a material fact or omit
to state any material fact required to be stated therein or necessary in order
to make the statements therein, in light of the circumstances under which they
are made, not misleading.

          Section 3.8  Finder's Fee.  No broker, finder, investment banker or
other intermediary (other than Lehman Brothers) is entitled to any brokerage,
finder's or other fee or commission in connection with the transactions
contemplated by this Agreement or by the Stock Purchase Agreement based upon
arrangements made by and on behalf of the Company.  The Company has heretofore
furnished to Parent a complete and correct copy of all agreements between the
Company and Lehman Brothers pursuant to which Lehman Brothers would be entitled
to any payment relating to the transactions contemplated hereby or by the Stock
Purchase Agreement.

          Section 3.9  Absence of Litigation.  Except as disclosed in the SEC
Reports filed prior to the date




                                      17
<PAGE>
 



hereof, as of the date hereof, there is no action, suit, claim, investigation or
proceeding pending against, or to the knowledge of the Company, threatened
against, the Company or any of its subsidiaries or any of their respective
properties before any court or arbitrator or any administrative, regulatory or
governmental body, or any agency or official which, individually or in the
aggregate, would reasonably be expected to have a Material Adverse Effect.
Except as disclosed in the SEC Reports filed prior to the date of this Agreement
or in Schedule 3.9, as of the date hereof, there is no action, suit, claim,
investigation or proceeding pending against, or to the knowledge of the Company,
threatened against, the Company or any of its subsidiaries or any of their
respective properties before any court or arbitrator or any administrative,
regulatory or governmental body, or any agency or official which (i) challenges
or seeks to prevent, enjoin, alter or delay the Merger or any of the other
transactions contemplated hereby or by the Stock Purchase Agreement; or (ii)
alleges criminal action or inaction.  Without limiting the generality of the
foregoing, as of the date hereof, there is no action, suit, claim, investigation
or proceeding relating to debarment or potential debarment pending against, or
to the knowledge of the Company, threatened against, the Company or any of its
subsidiaries before the Health Care Financing Administration, the Department of
Defense, the Inspector General of the Department of Health and Human Services or
any similar state agency which, individually or in the aggregate, would
reasonably be expected to have a Material Adverse Effect.  Except as disclosed
in the SEC Reports filed prior to the date of this Agreement, as of the date
hereof, neither the Company nor any of its subsidiaries nor any of their
respective properties is subject to any order, writ, judgment, injunction,
decree, determination or award having, or which would reasonably be expected to
have, a Material Adverse Effect or which would prevent or delay the consummation
of the transactions contemplated hereby.

          Section 3.10  Taxes.  Except as set forth in the SEC Reports filed
prior to the date of this Agreement or in Schedule 3.10(a), (a) the Company and
its subsidiaries have filed, been included in or sent, all material returns,
material declarations and reports and information returns and statements
required to be filed or sent by or relating to any of them relating to any Taxes
(as




                                      18
<PAGE>
 



defined below) with respect to any material income, properties or operations of
the Company or any of its subsidiaries (collectively, "Returns"); (b) as of the
time of filing, the Returns correctly reflected in all material respects the
facts regarding the income, business, assets, operations, activities and status
of the Company and its subsidiaries and any other material information required
to be shown therein; (c) the Company and its subsidiaries have timely paid or
made provision for all material Taxes that have been shown as due and payable on
the Returns that have been filed; (d) the Company and its subsidiaries have made
or will make provision for all material Taxes payable for any periods that end
before the Effective Time for which no Returns have yet been filed and for any
periods that begin before the Effective Time and end after the Effective Time to
the extent such Taxes are attributable to the portion of any such period ending
at the Effective Time; (e) the charges, accruals and reserves for taxes
reflected on the books of the Company and its subsidiaries are adequate under
generally accepted accounting principles to cover the Tax liabilities accruing
or payable by the Company and its subsidiaries in respect of periods prior to
the date hereof; (f) neither the Company nor any of its subsidiaries is
delinquent in the payment of any material Taxes or has requested any extension
of time within which to file or send any material Return (other than extensions
granted to the Company for the filing of its Returns as set forth in Schedule
3.10(a)), which Return has not since been filed or sent; (g) no material
deficiency for any Taxes has been proposed, asserted or assessed in writing
against the Company or any of its subsidiaries (or any member of any affiliated
or combined group of which the Company or any of its subsidiaries is or has been
a member for which either the Company or any of its subsidiaries could be
liable) other than those Taxes being contested in good faith by appropriate
proceedings and set forth in Schedule 3.10(b) (which shall set forth the nature
of the proceeding, the type of return, the deficiencies proposed, asserted or
assessed and the amount thereof, and the taxable year in question); (h) neither
the Company nor any of its subsidiaries has granted any extension of the
limitation period applicable to any material Tax claims other than those Taxes
being contested in good faith by appropriate proceedings; (i) neither the
Company nor any of its subsidiaries is subject to liability for Taxes of any
person (other than the




                                      19
<PAGE>
 



Company or its subsidiaries), including, without limitation, liability arising
from the application of U.S. Treasury Regulation section 1.1502-6 or any
analogous provision of state, local or foreign law; and (j) neither the Company
nor any of its subsidiaries is or has been a party to any material tax sharing
agreement with any corporation which is not currently a member of the affiliated
group of which the Company is currently a member.

          "Tax" means with respect to any person (i) any net income, gross
income, gross receipts, sales, use, ad valorem, franchise, profits, license,
withholding, payroll, employment, excise, severance, stamp, occupation, premium,
property, value-added, windfall profits, custom duty or other tax, governmental
fee, capital stock, social security (or similar), unemployment, disability,
transfer, registration, alternative or add-on minimum, estimated or other like
assessment or charge of any kind whatsoever, together with any interest and any
penalty, addition to tax or additional amount imposed by any taxing authority
(domestic or foreign) on such person and (ii) any liability of the Company or
any subsidiary for the payment of any amount of the type described in clause (i)
as a result of being a member of an affiliated or combined group.

          Section 3.11  Employee Benefits.  (a) Schedule 3.11(a) contains a true
and complete list of each bonus, deferred compensation, incentive compensation,
stock purchase, stock option, severance or termination pay, hospitalization or
other medical, dental, life, disability or other insurance, supplemental
unemployment benefits, profit-sharing, pension, savings or retirement plan,
program, agreement or arrangement, and each other employee benefit plan,
program, agreement or arrangement, sponsored, maintained or contributed to or
required to be contributed to by the Company or by any trade or business,
whether or not incorporated (an "ERISA Affiliate"), that together with the
Company would be deemed a "single employer" within the meaning of section 4001
of the Employee Retirement Income Security Act of 1974, as amended ("ERISA"),
for the benefit of any employee or terminated employee of the Company or any
ERISA Affiliate (the "Plans").  Schedule 3.11(a) identifies each of the Plans
that is an "employee benefit plan," as that term is defined in section 3(3) of
ERISA (the "ERISA Plans").




                                      20
<PAGE>
 



          (b)  With respect to each Plan, the Company has heretofore delivered
or made available to Parent true and complete copies of each of the following
documents (to the extent applicable):

               (i)  a copy thereof;

               (ii)  a copy of the most recent annual report and actuarial
     report, if required under ERISA, and the most recent report prepared with
     respect thereto in accordance with Statement of Financial Accounting
     Standards No. 87, Employer's Accounting for Pensions;

               (iii)  a copy of the most recent actuarial report prepared with
     respect thereto in accordance with Statement of Financial Accounting
     Standards No. 106, Employer's Accounting for Non-Pension Postretirement
     Benefits;

               (iv)  a copy of the most recent Summary Plan Description;

               (v)  if the Plan is funded through a trust or any third party
     funding vehicle, a copy of the trust or other funding agreement and the
     latest financial statements thereof; and

               (vi)  the most recent determination letter received from the
     Internal Revenue Service with respect to each Plan intended to qualify
     under section 401(a) of the Internal Revenue Code of 1986, as amended (the
     "Code").

          (c)  With respect to each ERISA Plan subject to Title IV of ERISA, no
material liability (other than liabilities for premiums due the Pension Benefit
Guaranty Corporation ("PBGC") (which premiums have been paid when due)) under
Title IV of ERISA has been incurred by the Company or any ERISA Affiliate that
has not been satisfied in full, and, to the knowledge of the Company, no
condition exists that presents a material risk to the Company or any ERISA
Affiliate of incurring a material liability under such Title.  To the extent
this representation applies to sections 4064, 4069 or 4204 of Title IV of ERISA,
it is made not only with respect to




                                      21
<PAGE>
 



each ERISA Plan but also with respect to any employee benefit plan, program,
agreement or arrangement subject to Title IV of ERISA to which the Company or
any ERISA Affiliate made, or was required to make, contributions during the five
(5)-year period ending on the Effective Time.

          (d)  The PBGC has not instituted proceedings to terminate any ERISA
Plan and, to the knowledge of the Company, no condition exists that presents a
material risk that such proceedings will be instituted.

          (e)  Except as set forth on Schedule 3.11(e), with respect to each
ERISA Plan subject to Title IV of ERISA, the present value of accrued benefits
under such plan, based upon the actuarial assumptions used for funding purposes
in the most recent actuarial report prepared by such plan's actuary with respect
to such plan did not exceed, as of its latest valuation date, the then current
value of the assets of such plan allocable to such accrued benefits.

          (f)  Neither the Company nor any ERISA Affiliate, nor, to the
knowledge of the Company, any ERISA Plan, nor any trust created thereunder, nor
any trustee or administrator thereof has engaged in a transaction in connection
with which the Company or any ERISA Affiliate, any ERISA Plan, any such trust,
or any trustee or administrator thereof, or any party dealing with any ERISA
Plan or any such trust could be subject to either a civil penalty assessed
pursuant to section 409 or 502(i) of ERISA or a Tax imposed pursuant to section
4975 or 4976 of the Code, except for such penalties and Taxes which would not,
individually or in the aggregate, have a Material Adverse Effect.

          (g)  No ERISA Plan or any trust established thereunder has incurred
any "accumulated funding deficiency" (as defined in section 302 of ERISA and
section 412 of the Code), whether or not waived, as of the last day of the most
recent fiscal year of such ERISA Plan ended prior to the Effective Time; and all
contributions required to be made with respect thereto (whether pursuant to the
terms of any ERISA Plan or otherwise) on or prior to the Effective Time have
been timely made.




                                      22
<PAGE>
 



          (h)  No ERISA Plan is a "multiemployer pension plan," as defined in
section 3(37) of ERISA, nor is any ERISA Plan a plan described in section
4063(a) of ERISA.

          (i)  To the knowledge of the Company, each Plan has been operated and
administered in all material respects in accordance with its terms and
applicable law, including but not limited to ERISA and the Code.

          (j)  Each ERISA Plan intended to be "qualified" within the meaning of
section 401(a) of the Code has been drafted with the intention to be so
qualified and has been submitted to the Internal Revenue Service along with a
request for a favorable determination letter on or before the date hereof, and
it is anticipated that each such plan will be modified so as to incorporate any
conforming amendments requested or required by the Internal Revenue Service as a
condition to the issuance of such favorable determination letter.

          (k)  To the Company's knowledge, except as reasonably estimated and as
set forth on Schedule 3.11(k), no amounts payable under the Plans as a result of
the consummation of the transactions contemplated by this Agreement will fail to
be deductible for federal income tax purposes by application of section 280G of
the Code.

          (l)  Except as set forth on Schedule 3.11(l), no Plan provides
benefits, including without limitation death or medical benefits (whether or not
insured), with respect to current or former employees of the Company or any
ERISA Affiliate beyond their retirement or other termination of service (other
than (i) coverage mandated by applicable law or (ii) death benefits or
retirement benefits under any "employee pension plan," as that term is defined
in section 3(2) of ERISA).

          (m)  Except as provided in Schedule 3.11(m), the consummation of the
transactions contemplated by this Agreement will not (i) entitle any current or
former employee or officer of the Company or any ERISA Affiliate to severance
pay, unemployment compensation or any other payment, except as expressly
provided in this Agreement or (ii) accelerate the time of payment or vest-




                                      23
<PAGE>
 



ing, or increase the amount of compensation due any such employee or officer.

          (n)  There are no pending or, to the knowledge of the Company,
threatened claims by or on behalf of any Plan, by any employee or beneficiary
covered under any such Plan, or otherwise involving any such Plan (other than
routine claims for benefits).

          (o)  The Company has reserved the right to amend or terminate any Plan
which is a welfare benefit plan, as that term is defined in section 3(l) of
ERISA.

          Section 3.12  Compliance.  Neither the Company nor any of its
subsidiaries is in violation of, or has violated, any applicable provisions of
(i) any laws, rules, statutes, orders, ordinances or regulations or (ii) any
note, bond, mortgage, indenture, contract, agreement, lease, license, permit,
franchise, or other instrument or obligations to which the Company or any of its
subsidiaries is a party or by which the Company or any of its subsidiaries or
its or any of their respective properties are bound or affected, which,
individually or in the aggregate, would have or be reasonably expected to have a
Material Adverse Effect.

          Section 3.13  Environmental Matters. (a) Except as set forth in
Schedule 3.13 and to the knowledge of the Company, the Company and its
subsidiaries are in compliance with all applicable Environmental Laws (which
compliance includes, but is not limited to, the possession by the Company and
its subsidiaries of all permits and other governmental authorizations required
under applicable Environmental Laws, and compliance with the terms and
conditions thereof), except for any noncompliance that individually or in the
aggregate would not reasonably be expected to have a Material Adverse Effect.
Except as set forth in Schedule 3.13, neither the Company nor any of its
subsidiaries has received any communication (written or oral), whether from a
governmental authority, citizens group, employee or otherwise, that alleges that
the Company is not in such compliance, and there are no past or present actions,
activities, circumstances, conditions, events or incidents that would prevent or
interfere with such compliance in the future.




                                      24
<PAGE>
 



          (b)  Except as set forth in Schedule 3.13, there is no Environmental
Claim pending or, to the knowledge of the Company, threatened against the
Company or any of its subsidiaries, or, to the knowledge of the Company, against
any person or entity whose liability for any Environmental Claim the Company or
any of its subsidiaries has retained or assumed either contractually or by
operation of law, which individually or in the aggregate would reasonably be
expected to have a Material Adverse Effect.

          (c) Except as set forth in Schedule 3.13, there are no past or present
actions, activities, circumstances, conditions, events or incidents (including,
without limitation, the release, emission, discharge, presence or disposal of
any Hazardous Material) which could form the basis of any Environmental Claim
against the Company or any of its subsidiaries, or, to the knowledge of the
Company, against any person or entity whose liability for any Environmental
Claim the Company or any of its subsidiaries has or may have retained or assumed
either contractually or by operation of law, which individually or in the
aggregate would reasonably be expected to have a Material Adverse Effect.

          (d) Except as set forth in Schedule 3.13, neither the Company nor any
of its subsidiaries has, and to the knowledge of Company, no other person has
Released, placed, stored, buried or dumped Hazardous Materials on, beneath or
adjacent to any property owned, operated or leased or formerly owned, operated
or leased by the Company or any of its subsidiaries, and neither the Company nor
any of its subsidiaries has received notice that it is a potentially responsible
party for the Cleanup of any property, whether or not owned or operated by the
Company or any of its subsidiaries, which individually or in the aggregate would
reasonably be expected to have a Material Adverse Effect.

          (e) The Company and its subsidiaries have delivered or otherwise made
available for inspection to Parent true, complete and correct copies and results
of any material reports, studies, analyses, tests or monitoring possessed or
initiated by the Company or any of its subsidiaries pertaining to Hazardous
Materials in, on, beneath or adjacent to the property owned or leased by the
Company or any of its subsidiaries or regarding




                                      25
<PAGE>
 
the Company's and its subsidiaries' compliance with applicable Environmental
Laws.

          (f)  Except as set forth in Schedule 3.13, no transfers of permits or
other governmental authorizations under Environmental Laws, and no additional
permits or other governmental authorizations under Environmental Laws, will be
required to permit the Company and its subsidiaries or the Surviving Corporation
and its subsidiaries, as the case may be, to be in full compliance with all
applicable Environmental Laws for the period immediately following the
transactions contemplated hereby, as conducted by the Company and its
subsidiaries immediately prior to the date hereof.  To the extent that such
transfers or additional permits and other governmental authorizations are
required, the Company and its subsidiaries agree to use reasonable best efforts
to effect such transfers and obtain such permits and other governmental
authorizations at the time such transfers, permits and other governmental
authorizations are required by law.

          (g) The following terms as used in this Section shall have the
following meanings:

          "Cleanup" means all actions required by governmental entities or
Environmental Laws to: (1) cleanup, remove, treat or remediate Hazardous
Materials in the indoor or outdoor environment; (2) prevent the Release of
Hazardous Materials so that they do not migrate, endanger or threaten to
endanger public health or welfare of the indoor or outdoor environment; (3)
perform pre-remedial studies and investigations and post-remedial monitoring and
care; or (4) respond to any government requests for information or documents in
any way relating to cleanup, removal, treatment or remediation or potential
cleanup, removal, treatment or remediation of Hazardous Materials in the indoor
or outdoor environment.

          "Environmental Claim" means any claim, action, cause of action,
investigation or notice (written or oral) by any person or entity alleging
potential liability (including, without limitation, potential liability for
investigatory costs, Cleanup costs, governmental response costs, natural
resources damages, property damages, personal injuries, or penalties) arising
out of, based on or resulting from (a) the presence, or Release into the indoor
or outdoor environment, of any Hazardous

                                       26
<PAGE>
 
Materials at any location, whether or not owned or operated by the Company or
any of its subsidiaries or (b) circumstances forming the basis of any violation,
or alleged violation, of any Environmental Law.

          "Environmental Laws" means all federal, state, local and foreign laws
and regulations relating to pollution or protection of human health or the
environment, including without limitation, laws relating to Releases or
threatened Releases of Hazardous Materials into the indoor or outdoor
environment (including, without limitation, ambient air, surface water, ground
water, land surface or subsurface strata) or otherwise relating to the
manufacture, processing, distribution, use, treatment, storage, Release,
disposal, transport or handling of Hazardous Materials and all laws and
regulations with regard to recordkeeping, notification, disclosure and reporting
requirements respecting Hazardous Materials.

          "Hazardous Materials" means all substances defined as Hazardous
Substances, Oils, Pollutants or Contaminants in the National Oil and Hazardous
Substances Pollution Contingency Plan, 40 C.F.R. (S) 300.5, or defined as such
by, or regulated as such under, any Environmental Law.

          "Release" means any release, spill, emission, discharge, leaking,
pumping, injection, deposit, disposal, discharge, dispersal, leaching or
migration into the indoor or outdoor environment (including, without limitation,
ambient air, surface water, groundwater and surface or subsurface strata) or
into or out of any property, including the movement of Hazardous Materials
through or in the air, soil, surface water, groundwater or property.

          Section 3.14  Intellectual Property.  Except to the extent that the
inaccuracy of any of the following (or the circumstances giving rise to such
inaccuracy) individually or in the aggregate, would not reasonably be expected
to have a Material Adverse Effect, and except as disclosed in the SEC Reports
filed prior to the date of this Agreement or as set forth in Schedule 3.14:  (1)
the Company and each of its subsidiaries owns, or is licensed or has the right
to use (in each case, free and clear of any Liens), all Intellectual Property
(as defined below) used in or necessary for the conduct of its business as
currently conducted; (2) to the knowledge of the Company,

                                       27
<PAGE>
 
the use of any Intellectual Property by the Company and its subsidiaries does
not infringe on or otherwise violate the rights of any person; (3) to the
knowledge of the Company, no product (or component thereof) or process used,
sold or manufactured by and/or for, or supplied to, the Company or any of its
subsidiaries infringes or otherwise violates the Intellectual Property of any
other person; and (4) to the knowledge of the Company, no person is challenging,
infringing on or otherwise violating any right of the Company or any of its
subsidiaries with respect to any Intellectual Property owned by and/or licensed
to the Company and its subsidiaries.  For purposes of this Agreement
"Intellectual Property" shall mean trademarks, service marks, brand names,
certification marks, trade dress, assumed names, trade names and other
indications of origin, the goodwill associated with the foregoing and
registrations in any jurisdiction of, and applications in any jurisdiction to
register, the foregoing, including any extension, modification or renewal of any
such registration or application; inventions, discoveries and ideas, whether
patentable or not in any jurisdiction; patents, applications for patents
(including, without limitation, divisions, continuations, continuations in part
and renewal applications), and any renewals, extensions or reissues thereof, in
any jurisdiction; nonpublic information, trade secrets and confidential
information and rights in any jurisdiction to limit the use or disclosure
thereof by any person; writings and other works, whether copyrightable or not in
any jurisdiction; registrations or applications for registration of copyrights
in any jurisdiction, and any renewals or extensions thereof; and any similar
intellectual property or proprietary rights.

          Section 3.15  Significant Agreements.  Schedule 3.15 sets forth a
complete and correct list of all contracts, agreements and commitments (oral or
written) between the Company or any of its subsidiaries, on the one hand, and on
the other hand, (i) DCC or any of its affiliates (other than the Company and its
subsidiaries) (excluding contracts, agreements and commitments which
collectively are immaterial to the Company and except for this Agreement and
certain other agreements entered into in connection with this Agreement and to
which Parent is a party or of which Parent is aware); (ii) Chugai Pharmaceutical
Co., Ltd. or any of its affiliates; or (iii) Tanabe Seiyaku Co., Ltd. or any of
its affiliates (the

                                       28
<PAGE>
 
contracts, agreements and commitments listed in Schedule 3.15, collectively, the
"Significant Agreements").  The Company has heretofore furnished or made
available to Parent complete and correct copies of the Significant Agreements,
each as amended or modified to the date hereof (including any waivers with
respect thereto).  Except as set forth on Schedule 3.4 or Schedule 3.15, each of
the Significant Agreements is in full force and effect and enforceable in
accordance with its terms; neither the Company nor any of its subsidiaries has
received any notice (written or oral) of cancellation or termination of, or any
expression or indication of an intention or desire to cancel or terminate, any
of the Significant Agreements; no Significant Agreement is the subject of, or,
to the knowledge of the Company, has been threatened to be made the subject of,
any arbitration, suit or other legal proceeding; with respect to any Significant
Agreement which by its terms will terminate as of a certain date unless renewed
or unless an option to extend such Significant Agreement is exercised, neither
the Company nor any of its subsidiaries has received any notice (written or
oral), or otherwise has any knowledge, that any such Significant Agreement will
not be so renewed or that any such extension option will not be exercised; and
there exists no event of default or occurrence, condition or act on the part of
the Company or any of its subsidiaries or, to the knowledge of the Company, on
the part of the other parties to the Significant Agreements which constitutes or
would constitute (with notice or lapse of time or both) a breach of or default
under any of the Significant Agreements, except to the extent that the
inaccuracy of the foregoing insofar as it relates to contracts, agreements and
commitments referenced in Section 3.15(i) would not, individually or in the
aggregate, have a Material Adverse Effect.

          Section 3.16  Insurance.  Schedule 3.16 sets forth a complete and
correct list of all material insurance policies (including a brief summary of
the nature and terms thereof and any amounts paid or payable to the Company or
any of its subsidiaries thereunder) providing coverage in favor of the Company
or any of its subsidiaries or any of their respective properties.  Each such
policy is in full force and effect, no notice of termination, cancellation or
reservation of rights has been received with respect to any such policy, there
is no default with respect to any provision contained in any such

                                       29
<PAGE>
 
policy, and there has not been any failure to give any notice or present any
claim under any such policy in a timely fashion or in the manner or detail
required by any such policy, except for any such failures to be in full force
and effect, any such terminations, cancellations, reservations or defaults, or
any such failures to give notice or present claims which, individually or in the
aggregate, would not reasonably be expected to have a Material Adverse Effect.
The coverage provided by such policies is, in the Company's judgment, reasonable
in scope and amount, in light of the risks attendant to the business and
activities of the Company and its subsidiaries.

          Section 3.17  Labor Matters.  Except as set forth in Schedule 3.17 and
except for normal and customary labor arrangements outside North America,
neither the Company nor any of its subsidiaries is a party to any collective
bargaining or other labor union contract applicable to persons employed by the
Company or any of its subsidiaries, no collective bargaining agreement is being
negotiated by the Company or any of its subsidiaries and the Company has no
knowledge of any material activities or proceedings of any labor union to
organize any of their respective employees.  There is no labor dispute, strike
or work stoppage against the Company or any of its subsidiaries pending or, to
the Company's knowledge, threatened which may interfere with the respective
business activities of the Company or any of its subsidiaries, except where such
dispute, strike or work stoppage would not reasonably be expected to have a
Material Adverse Effect.

          Section 3.18  FDA Matters.

          (a)  Schedule 3.18 sets forth a complete and correct list of all
products that are, directly or indirectly, being researched in human subjects or
distributed for commercial sale by the Company or any of its subsidiaries (the
"Products")(including, on such Schedule 3.18, a list of all material Licenses
(as defined below) for each Product that have been obtained by the Company or
any of its subsidiaries, or form the basis for manufacturing, distribution, sale
or human research of a Product by the Company or any of its subsidiaries).

                                       30
<PAGE>
 
          (b)  Except as set forth in Schedule 3.18, (i) with respect to each
Product: (A) the Company and its subsidiaries have obtained all applicable
approvals, clearances, authorizations, licenses and registrations required by
United States or foreign governments or government agencies, to permit the
manufacture, distribution, sale, marketing or human research of such Product
(collectively, "Licenses"); (B) the Company and its subsidiaries are in full
compliance with all terms and conditions of each License in each country in
which such Product is marketed, and with all requirements pertaining to the
manufacture, distribution, sale or human research of such Product which is not
required to be the subject of a License; (C) the Company and its subsidiaries
are in full compliance with all applicable requirements (as set forth in
relevant statutes and regulations) regarding registration, licensure or
notification for each site (in any country) at which such Product is
manufactured, processed, packed, held for distribution or from which it is
distributed; and (D) to the extent such product is intended for export from the
United States, the Company and its subsidiaries are in full compliance with
either all United States Food and Drug Administration (hereafter, "FDA")
requirements for marketing or 21 U.S.C. 381(e) or 382; (ii) all manufacturing
operations performed by the Company and its subsidiaries have been and are being
conducted in full compliance with the current good manufacturing practice,
including, but not limited to, the good manufacturing practice regulations
issued by FDA and counterpart requirements in the European Union and other
countries; (iii) all nonclinical laboratory studies, as described in 21 C.F.R.
58.3(d), sponsored by the Company or any of its subsidiaries have been and are
being conducted in full compliance with the good laboratory practice regulations
set forth in 21 C.F.R. Part 58 and counterpart requirements in the European
Union and other countries; and (iv) the Company and its subsidiaries are in full
compliance with all reporting requirements for all Licenses or plant
registrations described in the preceding clauses (b)(i)(A) and (b)(i)(C),
including, but not limited to, the adverse event reporting requirements for
drugs in 21 C.F.R. Parts 312 and 314 and for devices in 21 C.F.R. Parts 812 and
803; except, in the case of the preceding clauses (b)(i)(A) through (b)(i)(D),
inclusive, (b)(ii), (b)(iii) and (b)(iv), for any such failures to obtain or
noncompliances which, individually or in the aggregate, would not reasonably be
expected to

                                       31
<PAGE>
 
have a Material Adverse Effect.  Without limiting the generality of the
foregoing definition of "Licenses", such definition shall specifically include,
with respect to the United States, new drug applications, abbreviated new drug
applications, product license applications, investigational new drug
applications, premarket approval applications, premarket notifications under
Section 510(k) of the Federal Food, Drug, and Cosmetic Act, investigational
device exemptions, and product export applications issued by FDA, as well as
registrations issued by the Drug Enforcement Administration of the Department of
Justice.

          (c)  Except as set forth in Schedule 3.18, neither the Company nor any
of its subsidiaries nor any of their officers, employees or agents has made any
untrue statement of a material fact or fraudulent statement to FDA, failed to
disclose a fact required to be disclosed to FDA, or committed any act, made any
statement, or failed to make any statement, that would reasonably be expected to
provide a basis for FDA to invoke its policy respecting "Fraud, Untrue
Statements of Material Facts, Bribery, and Illegal Gratuities," set forth in 56
Fed. Reg. 46191 (September 10, 1991).

          (d)  The Company has provided or made available to Parent all
documents in its possession concerning communications to or from FDA, or
prepared by FDA, which bear in any material respect on compliance by the Company
and its subsidiaries with FDA regulatory requirements.


                                   ARTICLE IV

                     REPRESENTATIONS AND WARRANTIES OF DCC

          DCC represents and warrants to Parent and Acquisition as follows:

          Section 4.1  Organization. DCC is a corporation duly organized,
validly existing and in good standing under the laws of the State of Delaware.

          Section 4.2  Authority Relative to this Agreement.  DCC has all
necessary corporate power and authority to execute and deliver this Agreement,
to perform its

                                       32
<PAGE>
 
obligations hereunder and to consummate the transactions contemplated hereby.
The execution, delivery and performance of this Agreement and the consummation
of the transactions contemplated hereby have been duly and validly authorized by
the board of directors of DCC, and no other corporate proceedings on the part of
DCC are necessary to authorize this Agreement or to consummate the transactions
so contemplated.  This Agreement has been duly and validly executed and
delivered by DCC and, assuming it constitutes a valid and binding agreement of
the other parties hereto, constitutes a legal, valid and binding agreement of
DCC, enforceable against DCC in accordance with its terms.

          Section 4.3  Non-Contravention; Required Filings and Consents.  (a)
The execution, delivery and performance by DCC of this Agreement and the
consummation of the transactions contemplated hereby (including the Merger) do
not and will not (i) contravene or conflict with the Certificate of
Incorporation or By-Laws of DCC; (ii) assuming that all consents, authorizations
and approvals contemplated by subsection (b) below have been obtained and all
filings described therein have been made, contravene or conflict with or
constitute a violation of any provision of any law, regulation, judgment,
injunction, order or decree binding upon or applicable to DCC or any of its
properties; (iii) conflict with, or result in the breach or termination of any
provision of or constitute a default (with or without the giving of notice or
the lapse of time or both) under, or give rise to any right of termination,
cancellation, or loss of any benefit to which DCC is entitled under any
provision of any agreement, contract, license or other instrument binding upon
DCC or any of its properties, or allow the acceleration of the performance of,
any obligation of DCC under any indenture, mortgage, deed of trust, lease,
license, contract, instrument or other agreement to which DCC is a party or by
which DCC or any of its assets or properties is subject or bound; or (iv) result
in the creation or imposition of any Lien on any asset of DCC, except in the
case of clauses (ii), (iii) and (iv) for any such contraventions, conflicts,
violations, breaches, terminations, defaults, cancellations, losses,
accelerations and Liens which, individually or in the aggregate, would not
reasonably be expected to prevent DCC from performing its obligations hereunder.

                                       33
<PAGE>
 
          (b)  The execution, delivery and performance by DCC of this Agreement
and the consummation of the transactions contemplated hereby by DCC require no
action by or in respect of, or filing with, any governmental body, agency,
official or authority (either domestic or foreign) other than (i) compliance
with any applicable requirements of the HSR Act, the EC Merger Regulation and
the Canadian Competition Act; (ii) the filing of a notice pursuant to Exon-
Florio; (iii) compliance with any applicable requirements of the Exchange Act
and state securities, takeover and Blue Sky laws; and (iv) such actions or
filings which, if not taken or made, would not, individually or in the
aggregate, reasonably be expected to prevent DCC from performing its obligations
hereunder.

          Section 4.4  Absence of Litigation.  Except as previously disclosed by
DCC to the Company, Parent and Acquisition, as of the date hereof, there is no
action, suit, claim, investigation or proceeding pending against, or to the
knowledge of DCC, threatened against, DCC or any of its properties before any
court or arbitrator or any administrative, regulatory or governmental body, or
any agency or official which challenges or seeks to prevent, enjoin, alter or
delay the Merger or any of the other transactions contemplated by this Agreement
or the Stock Purchase Agreement.  As of the date hereof, neither DCC nor any of
its properties is subject to any order, writ, judgment, injunction, decree,
determination or award which would prevent or delay the consummation of the
transactions contemplated hereby.

          Section 4.5  Certain Matters Concerning the Company.  (a)  Except for
this Agreement and certain other agreements entered into in connection with this
Agreement and to which Parent is a party or of which Parent is aware, Schedule
4.5 sets forth a complete and correct list of all contracts, agreements and
commitments (oral or written) between the Company or any of its subsidiaries, on
the one hand, and DCC or any of its affiliates (other than the Company and its
subsidiaries), on the other hand (the "Dow Agreements").

          (b)  To the knowledge of DCC, and without having made any special
inquiry or investigation, except as disclosed in the SEC Reports filed prior to
the date  of this Agreement or as set forth on Schedule 3.5(b), the Company and
its subsidiaries have no liabilities of any

                                       34
<PAGE>
 
nature (whether accrued, absolute, contingent or otherwise), except for
liabilities incurred in the ordinary course of business since December 31, 1994
or which would not, individually or in the aggregate, have a Material Adverse
Effect.


                                   ARTICLE V

            REPRESENTATIONS AND WARRANTIES OF PARENT AND ACQUISITION

          Each of Parent and Acquisition represents and warrants to the Company
as follows:

          Section 5.1  Organization.  Each of Parent and Acquisition is a
corporation duly organized, validly existing and in good standing under the laws
of the State of Delaware and has all requisite corporate power and authority to
own, lease and operate its properties and to carry on its business as now being
conducted.  As of the closing pursuant to the Stock Purchase Agreement and as of
the Closing hereunder, Acquisition will be a direct wholly owned subsidiary of
Parent.

          Section 5.2  Authority Relative to this Agreement.  Each of Parent and
Acquisition has all necessary corporate power and authority to execute and
deliver this Agreement, to perform its obligations hereunder and to consummate
the transactions contemplated hereby.  The execution, delivery and performance
of this Agreement and the consummation of the transactions contemplated hereby
have been duly and validly authorized by the board of directors of Acquisition
and Parent and by the sole stockholder of Acquisition, and no other corporate
proceedings on the part of Parent or Acquisition are necessary to authorize this
Agreement or to consummate the transactions so contemplated.  This Agreement has
been duly and validly executed and delivered by each of Parent and Acquisition
and, assuming it constitutes a valid and binding agreement of the other parties
hereto, constitutes a legal, valid and binding agreement of each of Parent and
Acquisition, enforceable against each of Parent and Acquisition in accordance
with its terms.

          Section 5.3  Non-Contravention; Required Filings and Consents.  (a)
The execution, delivery and performance by Parent and Acquisition of this
Agreement and

                                       35
<PAGE>
 
the consummation of the transactions contemplated hereby (including the Merger)
do not and will not (i) contravene or conflict with the Certificate of
Incorporation or By-Laws of Parent or Acquisition; (ii) assuming that all
consents, authorizations and approvals contemplated by subsection (b) below have
been obtained and all filings described therein have been made, contravene or
conflict with or constitute a violation of any provision of any law, regulation,
judgment, injunction, order or decree binding upon or applicable to Parent or
Acquisition or any of their respective properties; (iii) conflict with, or
result in the breach or termination of any provision of or constitute a default
(with or without the giving of notice or the lapse of time or both) under, or
give rise to any right of termination, cancellation, or loss of any benefit to
which Parent or Acquisition is entitled under any provision of any agreement,
contract, license or other instrument binding upon Parent, Acquisition or any of
their respective properties, or allow the acceleration of the performance of,
any obligation of Parent or Acquisition under any indenture, mortgage, deed of
trust, lease, license, contract, instrument or other agreement to which Parent
or Acquisition is a party or by which Parent or Acquisition or any of their
respective assets or properties is subject or bound; or (iv) result in the
creation or imposition of any Lien on any asset of Parent or Acquisition, except
in the case of clauses (ii), (iii) and (iv) for any such contraventions,
conflicts, violations, breaches, terminations, defaults, cancellations, losses,
accelerations and Liens which, individually or in the aggregate, would not
reasonably be expected to prevent the consummation of the Merger.

          (b)  The execution, delivery and performance by Parent and Acquisition
of this Agreement and the consummation of the transactions contemplated hereby
(including the Merger) by Parent and Acquisition require no action by or in
respect of, or filing with, any governmental body, agency, official or authority
(either domestic or foreign) other than (i) the filing of a certificate of
merger in accordance with Delaware Law; (ii) compliance with any applicable
requirements of the HSR Act, the EC Merger Regulation and the Canadian
Competition Act; (iii) compliance with any applicable requirements of the
Exchange Act and state securities, takeover and Blue Sky laws; (iv) the filing
of a notice pursuant to Exon-Florio; and (v) such actions or filings which, if

                                       36
<PAGE>
 
not taken or made, would not, individually or in the aggregate, reasonably be
expected to prevent the consummation of the Merger.

          Section 5.4  Absence of Litigation.  Except as previously disclosed by
Parent and Acquisition to the Company and DCC, as of the date hereof, there is
no action, suit, claim, investigation or proceeding pending against, or to the
knowledge of Parent and Acquisition, threatened against, Parent or Acquisition
or any of their respective properties before any court or arbitrator or any
administrative, regulatory or governmental body, or any agency or official which
challenges or seeks to prevent, enjoin, alter or delay the Merger or any of the
other transactions contemplated by this Agreement or the Stock Purchase
Agreement.  As of the date hereof, neither Parent nor Acquisition nor any of
their respective properties is subject to any order, writ, judgment, injunction,
decree, determination or award which would prevent or delay the consummation of
the transactions contemplated hereby.

          Section 5.5  Proxy Statement; Schedule 13E-3.  None of the information
provided by Parent or Acquisition  specifically for use in the Proxy Statement
shall, at the time filed with the SEC, at the time mailed to the Company's
stockholders, at the time of the Stockholders' Meeting or at the Effective Time,
contain any untrue statement of a material fact or omit to state any material
fact required to be stated therein or necessary in order to make the statements
therein, in light of the circumstances under which they are made, not
misleading.  None of the information provided by Parent or Acquisition
specifically for use in the Schedule 13E-3(if required to be filed) will at the
time the Schedule 13E-3 or any amendments thereto are filed with the SEC,
contain any untrue statement of a material fact or omit to state any material
fact required to be stated therein or necessary in order to make the statements
therein, in light of the circumstances under which they are made, not
misleading.

          Section 5.6  No Prior Activities.  Since the date of its
incorporation, Acquisition has not engaged in any activities other than in
connection with or as contemplated by this Agreement or the Stock Purchase
Agreement or in connection with arranging any financing re-

                                       37
<PAGE>
 
quired to consummate the transactions contemplated hereby and thereby.

          Section 5.7  Financing.  Upon the terms and subject to the conditions
of this Agreement, Parent or Acquisition will have available all funds necessary
to satisfy its obligation to pay the aggregate Merger Consideration.

          Section 5.8  Parent Not an Interested Stockholder.  As of the date
hereof, (i) neither Parent nor any of its affiliates is, with respect to the
Company, an "Interested Stockholder", as such term is defined in Section 203 of
Delaware Law and (ii) except to the extent that Parent and its affiliates may be
deemed to hold Shares as a result of this Agreement or the Stock Purchase
Agreement, Parent and its affiliates collectively do not hold directly or
indirectly five percent (5%) or more of the outstanding voting securities of the
Company.


                                   ARTICLE VI

                                   COVENANTS

          Section 6.1  Conduct of Business of the Company.  Except as otherwise
expressly provided in this Agreement, during the period from the date hereof to
the Effective Time, the Company and its subsidiaries will each conduct its
operations according to its ordinary course of business consistent with past
practice, and the Company and its subsidiaries will each use its reasonable best
efforts to preserve intact its business organization, to keep available the
services of its officers and employees and to maintain existing relationships
with licensors, licensees, suppliers, contractors, distributors, customers and
others having business relationships with it.  Without limiting the generality
of the foregoing, and except as disclosed in the SEC Reports filed prior to the
date of this Agreement, as otherwise expressly provided in this Agreement, as
required by law or as set forth in Schedule 6.1, prior to the Effective Time,
neither the Company nor any of its subsidiaries will, without the prior written
consent of Acquisition (which consent will be deemed to include the consent of
any person designated from time to time by Acquisition by written notice to the
Company):

                                       38
<PAGE>
 
          (a)  amend its certificate or articles of incorporation or by-
laws or equivalent organizational documents;

          (b)  authorize for issuance, issue, sell, deliver or agree or commit
to issue, sell or deliver (whether through the issuance or granting of options,
warrants, commitments, subscriptions, rights to purchase or otherwise) any stock
of any class or any other securities or equity equivalents (including, without
limitation, stock appreciation rights), except as required by option agreements
as in effect as of the date hereof or upon any conversion of Series A Preferred
Shares, or amend any of the terms of any such securities or agreements
outstanding as of the date hereof;

          (c)  split, combine or reclassify any shares of its capital stock,
declare, set aside or pay any dividend or other distribution (whether in cash,
stock, or property or any combination thereof) in respect of its capital stock
(except that the Company may declare and pay dividends on the Series A Preferred
Shares in accordance with their terms and may declare and pay its regular
quarterly cash dividends in respect of issued and outstanding Shares in an
amount not to exceed $0.25 per Share per quarter; provided, that the record
dates for determining the holders of Shares entitled to receive such regular
quarterly cash dividends shall be the close of business on the last business day
of each calendar quarter), or, except for the redemption of the Series A
Preferred Shares pursuant hereto and pursuant to the Company's Restated
Certificate of Incorporation, redeem, repurchase or otherwise acquire any of its
securities or any securities of its subsidiaries;

          (d)  (i) incur any indebtedness for borrowed money (except for short
term indebtedness incurred in the ordinary course of business consistent with
past practice pursuant to existing lines of credit) or issue any debt securities
or, except in the ordinary course of business consistent with past practice,
assume, guarantee or endorse the obligations of any other person; (ii) make any
loans, advances or capital contributions to, or investments in, any other person
(other than to wholly owned subsidiaries of the Company); (iii) pledge or
otherwise encumber shares of capital stock of the Company or any of its
subsidiaries; (iv) enter into or invest in

                                       39
<PAGE>
 
any Derivative Financial Instruments except in the ordinary course of business
consistent with the Company's current investment and risk management policies;
or (v) except in the ordinary course of business consistent with past practice,
mortgage or pledge any of its assets, tangible or intangible, or create or
suffer to exist any Lien thereupon;

          (e)  enter into, adopt or (except as may be required by law or the
terms of any such arrangement) amend or terminate any bonus, profit sharing,
compensation, severance, termination, stock option, stock appreciation right,
restricted stock, performance unit, stock equivalent, stock purchase agreement,
pension, retirement, deferred compensation, employment, severance or other
employee benefit agreement, trust, plan, fund or other arrangement for the
benefit or welfare of any director, officer or employee, or (except, in the case
of employees who are not officers or directors, for normal compensation
increases in the ordinary course of business consistent with past practice that,
in the aggregate, do not result in a material increase in benefits or
compensation expense to the Company) increase in any manner the compensation or
benefits of any director, officer or employee or pay any benefit not required by
any plan or arrangement as in effect as of the date hereof (including, without
limitation, the granting of stock options, restricted stock, stock appreciation
rights or performance units);

          (f)  acquire, sell, lease or dispose of any assets outside the
ordinary course of business or any assets which in the aggregate are material to
the Company and its subsidiaries, taken as a whole, or enter into any contract,
agreement, commitment or transaction outside the ordinary course of business
consistent with past practice;

          (g)  change any of the accounting principles or practices used by it,
except as may be required as a result of a change in law, SEC guidelines or
generally accepted accounting principles;

          (h)  (i) acquire (by merger, consolidation, or acquisition of stock or
assets) any corporation, partnership or other business organization or division
thereof; (ii) authorize any new capital expenditure or

                                       40
<PAGE>
 
expenditures which, individually, is in excess of $1,000,000 or, in the
aggregate, are in excess of $5,000,000; (iii) settle any litigations for amounts
in excess of $200,000 individually or $1,000,000 in the aggregate; or (iv) enter
into or amend any contract, agreement, commitment or arrangement with respect to
any of the foregoing;

          (i) make any Tax election or settle or compromise any Tax liability,
other than in the ordinary course of business;

          (j)  pay, discharge or satisfy any claims, liabilities or obligations
(absolute, accrued, asserted or unasserted, contingent or otherwise), other than
the payment, discharge or satisfaction in the ordinary course of business
consistent with past practice or in accordance with their terms, of liabilities
set forth in Schedule 3.5(b) or reflected or reserved against in the
consolidated financial statements (or the notes thereto) of the Company and its
consolidated subsidiaries or incurred in the ordinary course of business
consistent with past practice;

          (k)  terminate, modify, amend or waive compliance with any provision
of any of the Significant Agreements, or fail to take any action necessary to
preserve the benefits of any Significant Agreement to the Company or any of its
subsidiaries; or

          (l) take, or agree in writing or otherwise to take, any of the actions
described above in Section 6.1.

          Section 6.2  Boards of Directors and Committees; Section 14(f).

          (a)  Promptly following the purchase by Acquisition, Parent or their
affiliates of the Dow Shares and from time to time thereafter, Acquisition shall
be entitled to designate up to such number of directors, rounded up to the next
whole number, on the Board that equals the product of (i) the total number of
directors on the Board (giving effect to the election of any additional
directors pursuant to this Section) and (ii) the percentage that the number of
Shares owned by Acquisition and its affiliates (including any Shares purchased
pursu-

                                       41
<PAGE>
 
ant to the Stock Purchase Agreement) bears to the total number of outstanding
Shares, and the Company shall, upon request by Acquisition, promptly either
increase the size of the Board or use its reasonable best efforts to secure the
resignation of such number of directors as is necessary to enable Acquisition's
designees to be elected to the Board and shall cause Acquisition's designees to
be so elected.  Promptly upon request by Acquisition, the Company will use its
reasonable best efforts to cause persons designated by Acquisition to constitute
the same percentage as is on the Board of (i) each committee of the Board, (ii)
each board of directors of each subsidiary of the Company designated by
Acquisition and (iii) each committee of each such board.  Simultaneously with
the purchase by Acquisition, Parent or their affiliates of the Dow Shares, DCC
shall use its reasonable best efforts to cause each employee of DCC who is on
the Board to resign from the Board and from the board of directors of any
subsidiary of the Company on which such individual serves.  Subject to the
foregoing, the Company shall use its reasonable best efforts to ensure that all
of the members of the Board as of the date hereof who are not employees of DCC
shall remain members of the Board until the Effective Time.

          (b)  The Company's obligations to appoint designees to the Board shall
be subject to Section 14(f) of the Exchange Act, and Rule 14f-1 promulgated
thereunder.  As promptly as practicable following the date of this Agreement,
the Company shall take all actions required pursuant to Section 14(f) and Rule
14f-1 in order to fulfill its obligations under this Section 6.2 and shall file
with the SEC and distribute to its stockholders such information as is required
under Section 14(f) and Rule 14f-1.  Parent or Acquisition will supply to the
Company in writing and be solely responsible for any information with respect to
either of them and their nominees, officers, directors and affiliates required
by Section 14(f) and Rule 14f-1.

          (c)  Following the election or appointment of Acquisition's designees
pursuant to this Section 6.2 and prior to the Effective Time, any amendment of
this Agreement or the Restated Certificate of Incorporation or By-Laws of the
Company, any termination of this Agreement by the Company, any extension by the
Company of the time for the performance of any of the obligations or other

                                       42
<PAGE>
 
acts of Parent or Acquisition or any waiver of any of the Company's rights
hereunder, will require the concurrence of a majority of the directors of the
Company then in office who are not designees of Acquisition or employees of DCC

or the Company.  From and after the purchase of the Dow Shares by Acquisition,
Parent or their affiliates and prior to the Effective Time, Parent and
Acquisition will cooperate with the Company to ensure that the Board at all
times includes at least two directors who are not designees of Acquisition or
employees of DCC or the Company.

          Section 6.3  Proxy Statement; Schedule 13E-3.

          (a)  The Company shall, as promptly as practicable following the date
hereof, prepare and file the Proxy Statement with the SEC under the Exchange
Act.  As soon as practicable following completion of review of the Proxy
Statement by the SEC, the Company shall mail the Proxy Statement to its
stockholders who are entitled to vote at the Stockholders' Meeting.  Subject to
the fiduciary obligations of the Board under applicable law, the Proxy Statement
shall contain the recommendation of the Board that the stockholders of the
Company adopt this Agreement and the Merger.

          (b)  In the event Parent and the Company determine that the Schedule
13E-3 is required to be filed with the SEC in connection with the Merger, then,
as promptly as practicable following notice of such determination, the Company,
Parent and Acquisition shall prepare and file the Schedule 13E-3 with the SEC.

          (c)  The Company, Parent and Acquisition shall cooperate with one
another in the preparation and filing of the Proxy Statement and the Schedule
13E-3 (if required to be filed) and shall use their reasonable best efforts to
promptly obtain and furnish the information required to be included in the Proxy
Statement and the Schedule 13E-3 and to respond promptly to any comments or
requests made by the SEC with respect to the Proxy Statement or the Schedule
13E-3 (if required to be filed).  Each party hereto shall promptly notify the
other parties of the receipt of comments of, or any requests by, the SEC with
respect to the Proxy Statement or the Schedule 13E-3 (if required to be filed),
and shall promptly supply the other parties with copies of all correspon-

                                       43
<PAGE>
 
dence between such party (or its representatives) and the SEC (or its staff)
relating thereto.  The Company, Parent and Acquisition each agrees to correct
any information provided by it for use in the Proxy Statement or the Schedule
13E-3 (if required to be filed) which shall have become, or is, false or
misleading.

          Section 6.4  Access to Information.  (a) Subject to applicable law and
the agreements set forth in Section 6.4(b), between the date hereof and the
Effective Time, the Company will give each of Parent and Acquisition and their
counsel, financial advisors, auditors, and other authorized representatives
reasonable access to all employees, plants, offices, warehouses and other
facilities and to all books and records of the Company and its subsidiaries,
will permit each of Parent and Acquisition and their respective counsel,
financial advisors, auditors and other authorized representatives to make such
inspections as Parent or Acquisition may reasonably require and will cause the
Company's officers and those of its subsidiaries to furnish Parent or
Acquisition or their representatives with such financial and operating data and
other information with respect to the business and properties of the Company and
any of its subsidiaries as Parent or Acquisition may from time to time
reasonably request.  No investigation pursuant to this Section 6.4 shall affect
any representations or warranties of the parties herein or the conditions to the
obligations of the parties hereunder.  The foregoing shall not require the
Company to permit any inspection, or to disclose any information, which in the
reasonable judgment of the Company would result in the disclosure of any trade
secrets of third parties or violate any obligation of the Company with respect
to confidentiality if the Company shall have used reasonable efforts to obtain
the consent of such third party to such inspection or disclosure.

          (b)  Each of Parent and Acquisition agrees to be bound by the
confidentiality agreement, dated as of August 18, 1994 (the "Confidentiality
Agreement"), among Hoechst AG ("HAG"), Hoechst Celanese Corporation ("HCC"),
Roussel Uclaf S.A. ("RU"), DCC and the Company as if the references to HAG, HCC
and RU therein were to Parent and Acquisition, except that Parent and
Acquisition may (i) enter into this Agreement and the Stock Purchase Agreement
and (ii) acquire Shares pursuant to the Merger and the Stock Purchase Agreement.

                                       44
<PAGE>
 
          Section 6.5  Reasonable Best Efforts.  Subject to the terms and
conditions herein provided, each of the parties hereto agrees to use its
reasonable best efforts to take, or cause to be taken, all actions, and to do,
or cause to be done, all things reasonably necessary, proper or advisable under
applicable laws and regulations to consummate and make effective the
transactions contemplated by this Agreement and the Stock Purchase Agreement.
Without limiting the generality of the foregoing, Parent, Acquisition, DCC and
the Company shall cooperate with one another (i) in the preparation and filing
of any required filings under the HSR Act and the other laws referred to in
Sections 3.4(b), 4.3(b) and 5.3(b); (ii) in determining whether action by or in
respect of, or filing with, any governmental body, agency, official or authority
(either domestic or foreign) is required, proper or advisable or any actions,
consents, waivers or approvals are required to be obtained from parties to any
contracts, in connection with the transactions contemplated by this Agreement
and the Stock Purchase Agreement; and (iii) in seeking timely to obtain any such
actions, consents and waivers and to make any such filings.  In case at any time
after the Effective Time any further action is necessary or desirable to carry
out the purposes of this Agreement, the proper officers and directors of each
party hereto shall take all such necessary action.

          Section 6.6  Public Announcements.  Parent and Acquisition, on the one
hand, and DCC and the Company, on the other hand, will consult with each other
before issuing any press release with respect to the transactions contemplated
by this Agreement and the Stock Purchase Agreement, and shall not issue any such
press release prior to such consultation, except as may be required by
applicable law or by applicable rules of any securities exchange.

          Section 6.7  Indemnification; Insurance.

          (a)  From and after the purchase by Acquisition, Parent or their
affiliates of the Dow Shares, Parent and Acquisition shall indemnify and hold
harmless each person who is, or has been at any time prior to the date hereof or
who becomes prior to the Effective Time, an officer, director or employee of the
Company or any of its subsidiaries (collectively, the "Indemnified Parties"

                                       45
<PAGE>
 
and individually, the "Indemnified Party") against all losses, liabilities,
expenses, claims or damages in connection with any claim, suit, action,
proceeding or investigation based in whole or in part on the fact that such
Indemnified Party is or was a director, officer or employee of the Company or
any of its subsidiaries and arising out of acts or omissions occurring prior to
and including the Effective Time (including but not limited to the transactions
contemplated by this Agreement) to the fullest extent permitted by Delaware Law,
for a period of not less than six years following the Effective Time; provided
that in the event any claim or claims are asserted or made within such six-year
period, all rights to indemnification in respect of any such claim or claims
shall continue until final disposition of any and all such claims.

          (b)  Parent shall cause the Certificate of Incorporation and By-Laws
of the Surviving Corporation and its subsidiaries to include provisions for the
limitation of liability of directors and indemnification of the Indemnified
Parties to the fullest extent permitted under applicable law and shall not
permit the amendment of such provisions in any manner adverse to the Indemnified
Parties, as the case may be, without the prior written consent of such persons,
for a period of six years from and after the date hereof.

          (c)  Without limitation of the foregoing, in the event any such
Indemnified Party is or becomes involved in any capacity in any action,
proceeding or investigation in connection with any matter, including, without
limitation, the transactions contemplated by this Agreement, occurring prior to,
and including, the Effective Time, Parent will pay as incurred such Indemnified
Party's legal and other expenses (including the cost of any investigation and
preparation) incurred in connection therewith.  Parent shall pay all expenses,
including attorneys' fees, that may be incurred by any Indemnified Party in
enforcing the indemnity and other obligations provided for in this Section 6.7
or any action involving an Indemnified Party resulting from the transactions
contemplated by this Agreement.

          (d)  For six years after the Effective Time, the Surviving Corporation
shall cause to be maintained the current policies of directors' and officers'

                                       46
<PAGE>
 
liability insurance maintained by the Company (provided that the Surviving
Corporation may substitute therefor policies of at least the same coverage
containing terms and conditions which are substantially equivalent) with respect
to matters occurring prior to the Effective Time, to the extent such policies
are available; provided, that in no event shall the Surviving Corporation be
required to expend, in order to maintain or procure insurance coverage pursuant
to this Section 6.7(c), any amount per annum greater than 125% of the current
annual premiums paid by the Company for such insurance (which the Company
represents and warrants to be not more than $620,000).

          (e)  Any determination to be made as to whether any Indemnified Party
has met any standard of conduct imposed by law shall be made by legal counsel
reasonably acceptable to such Indemnified Party, Parent and the Surviving
Corporation, retained at Parent's and the Surviving Corporation's expense.

          (f)  This Section 6.7 is intended to benefit the Indemnified Parties
and their respective heirs, executors and personal representatives and shall be
binding on the successors and assigns of Parent, Acquisition and the Surviving
Corporation.

          Section 6.8  Notification of Certain Matters.  The Company shall give
prompt notice to Parent or Acquisition, and Parent or Acquisition shall give
prompt notice to the Company, upon becoming aware of (i) the occurrence, or non-
occurrence, of any event the occurrence, or non-occurrence of which would cause
any representation or warranty contained in this Agreement to be untrue or
inaccurate and (ii) any failure of the Company, Parent or Acquisition, as the
case may be, to comply with or satisfy any covenant, condition or agreement to
be complied with or satisfied by it hereunder; provided, that the delivery of
any notice pursuant to this Section 6.8 shall not limit or otherwise affect the
remedies available hereunder to the party receiving such notice.

          Section 6.9  Redemption of Series A Preferred Stock; Termination of
Stock Plans.  (a) Effective immediately prior to the Merger, the Company shall
redeem for cash all of the outstanding Series A Preferred Shares at the
applicable redemption price determined in accordance with the Company's Restated
Certificate of Incorporation

                                       47
<PAGE>
 
(which shall not exceed $37.41 per Series A Preferred Share).  Upon such
redemption, the Company shall retire the shares so redeemed and restore such
shares to the status of authorized but unissued shares of Preferred Stock, par
value $1.00 per share, undesignated as to series.  The foregoing provisions of
this Section 6.9 shall be of no further force or effect if the Company purchases
all of the outstanding Series A Preferred Shares prior to the Merger.

          (b)  Except as may be otherwise agreed to by the Parent and the
Company, the Company Plans shall terminate as of the Effective Time.  Prior to
the purchase by Parent, Acquisition and their affiliates of the Dow Shares, the
Board (or, if appropriate, any committee thereof) shall adopt such resolutions
or take such other actions as are required to (i) effect the transactions
contemplated by Section 1.8 hereof and (ii) with respect to any stock option,
stock appreciation or other stock benefit plan of the Company or any of its
subsidiaries not addressed by the preceding clause (i), ensure that, following
the Effective Time, no participant therein shall have any right thereunder to
acquire any capital stock of the Surviving Corporation or any subsidiary
thereof.

          (c)  Between the date of this Agreement and the Effective Time, the
Company shall reasonably cooperate with Parent and Acquisition in structuring
transactions (including those described in Sections 1.8(a), 1.8(b) and 6.9(b))
with respect to Employee Options and Performance Shares so as to optimize the
tax treatment of the Company, Parent and Acquisition in connection therewith.

          Section 6.10  No Solicitation.  (a) The Company will immediately cease
any existing discussions or negotiations with any third parties conducted prior
to the date hereof with respect to any Acquisition Proposal (as defined below).
The Company shall not, directly or indirectly, through any officer, director,
employee, representative or agent or any of its subsidiaries, (i) solicit,
initiate, or encourage any inquiries or proposals that constitute, or would lead
to, a proposal or offer for a merger, consolidation, business combination, sale
of substantial assets, sale of a substantial percentage of shares of capital
stock (including, without limita-

                                       48
<PAGE>
 
tion, by way of a tender offer) or similar transactions involving the Company or
any of its subsidiaries, other than the transactions contemplated by this
Agreement (any of the foregoing inquiries or proposals being referred to in this
Agreement as an "Acquisition Proposal"), (ii) subject to the fiduciary duties of
the Board under applicable law, engage in negotiations or discussions
concerning, or provide any non-public information to any person or entity
relating to, any Acquisition Proposal, or (iii) agree to, approve or recommend
any Acquisition Proposal; provided, that nothing contained in this Section 6.10
shall prevent the Company from, and the Company may without any liability for
breach of this Agreement, (A) furnish information to, or enter into discussions
or negotiations with, any person in connection with an unsolicited bona fide
written Acquisition Proposal by such person or recommend an Acquisition Proposal
to the stockholders of the Company, if and only to the extent that the Board
determines in good faith after consultation with outside legal counsel that such
action is necessary for the Board to comply with its fiduciary duties to
stockholders under applicable law and prior to furnishing such information to,
or entering into discussions or negotiations with, such person, the Board
receives from such person an executed confidentiality agreement with terms no
less favorable to the Company than those contained in the Confidentiality
Agreement; or (B) comply with Rules 14d-9 and 14e-2 promulgated under the
Exchange Act with regard to an Acquisition Proposal.

          (b)  The Company shall notify Parent immediately (and no later than 24
hours) after receipt by the Company of any Acquisition Proposal or any request
for non-public information in connection with an Acquisition Proposal or for
access to the properties, books or records of the Company by any person or
entity that informs the Company that it is considering making, or has made, an
Acquisition Proposal.  Such notice shall be made orally and shall indicate the
identity of the offeror and the terms and conditions of such proposal, inquiry
or contract.

          Section 6.11  Undisclosed Agreements.  If, after the date hereof,
Parent becomes aware that there are any contracts, agreements and commitments
(oral or written; provided, that oral agreements referred to in this Section
6.11 shall not include oral agreements

                                       49
<PAGE>
 
entered into pursuant to any contracts, agreements or commitments listed on
Schedule 4.5) existing as of the date of this Agreement between the Company or
any of its subsidiaries, on the one hand, and DCC or any of its affiliates
(other than the Company and its subsidiaries), on the other hand, which are not
set forth in Schedule 4.5, then, from and after the purchase by Acquisition,
Parent or their affiliates of the Dow Shares, the Company and, following the
Effective Time, the Surviving Corporation shall have the right, exercisable
within 60 days after Parent becomes aware of such contract, agreement or
commitment, to, at its sole discretion, terminate (effective as of the date on
which Acquisition, Parent or their affiliates purchase the Dow Shares; provided,
that any payments (not in excess of the fair market value of the goods or
services to which such payments relate) made to DCC or any of its affiliates
pursuant to such contract, agreement or commitment shall not be required to be
repaid pursuant to this clause) any or all of such contracts, agreements or
commitments, and neither Parent nor the Company nor any of their respective
subsidiaries shall incur or be subject to any penalty or liability whatsoever
with respect to such termination.  DCC agrees to be, and agrees to cause its
applicable affiliates to be, bound by any such termination.  The termination
provisions set forth in this Section 6.11 shall be the sole remedy of Parent,
Acquisition and the Company, and their affiliates, for any breach of the
representations and warranties set forth in Section 4.5.

          Section 6.12  Employee Matters.  (a) For a period of at least two
years after the Effective Time, Parent shall cause the Surviving Corporation to
provide benefit plans (other than any stock-based plans, programs or
arrangements) that are in the aggregate substantially as favorable as the
Company's existing compensation, welfare and pension benefit plans, programs and
arrangements for the benefit of current and former employees and directors of
the Company (subject to such modification as may be required by applicable law).

          (b)  If any employee of the Company or any of its subsidiaries becomes
a participant in any employee benefit or compensation plan, arrangement,
practice or policy of Parent or any affiliate of Parent, such employee shall be
given credit for eligibility and vesting under such plan for all service prior
to the Effective

                                       50
<PAGE>
 



Time with the Company, any of its subsidiaries, affiliates or any predecessors
for which the employee would have been credited in the Company's plans
immediately prior to the Effective Time.

          Section 6.13  Acquisition.  (a) Prior to the purchase by Acquisition,
Parent or their affiliates of the Dow Shares, each of Parent and Acquisition
shall take all steps necessary to cause Acquisition to become a direct wholly
owned subsidiary of Parent and remain so until the Effective Time.

          (b)  Parent will take all action necessary to cause Acquisition to
perform its obligations hereunder and to consummate the Merger on the terms and
conditions set forth herein.

          Section 6.14  Certain Intercompany Accounts and Matters.  Effective as
of the purchase by Parent, Acquisition or their affiliates of the Dow Shares,
DCC and its subsidiaries, on the one hand, and the Company and its subsidiaries,
on the other hand, shall repay all outstanding intercompany obligations between
them for borrowed money, in accordance with the terms of such obligations;
provided, that any such obligations between Marion Merrell Dow KK and Dow
Chemical Japan ("Japanese Intercompany Accounts") may remain outstanding until
December 31, 1995; provided, further, that Parent shall cause Marion Merrell Dow
KK to perform its obligations with respect to the Japanese Intercompany Accounts
and Parent  guarantees the performance of the obligations of Marion Merrell Dow
KK with respect to the Japanese Intercompany Accounts.

          Section 6.15  Stock Purchase Agreement.  Upon the terms and subject to
the conditions set forth in the Stock Purchase Agreement, Parent shall cause
Acquisition to, and Acquisition shall, purchase the Dow Shares.

          Section 6.16  Name Changes. (a) Within 90 days following the purchase
of the Dow Shares by Parent, Acquisition or their affiliates, the Company shall
cause its subsidiaries to delete "DOW" from their respective company names and
within the same 90 days initiate all the necessary legal filings with the
appropriate local governmental authority to effectuate a name change to a new
name that does not contain DOW or a name confusingly




                                      51
<PAGE>


 

similar to DOW.  Within eighteen (18) months following the purchase of the Dow
Shares by Parent, Acquisition or their affiliates, the Company and its
subsidiaries will also replace their current names, which include DOW, to their
new company names on all stationary, business cards, real and personal property,
directories, labels, advertising and promotional material, drug registrations
and any and all applications, registrations or other documents filed or to be
filed with international, national and local governmental offices, agencies or
authorities in any country.

          (b)  From and after the date Acquisition, Parent or their affiliates
purchase the Dow Shares, the Company shall indemnify and hold DCC and its
subsidiaries harmless from and against the out-of-pocket costs and expenses
described in the next sentence of this Section 6.16(b) which DCC or its
subsidiaries incur as a result of defending any suits, claims, administrative or
legal proceedings brought against DCC or any of its subsidiaries to the extent
that the basis of any such suit, claim or proceeding is premised on the use of
the name and trademark DOW by the Company or any of its subsidiaries or on their
products.  The Company's indemnification under this Section 6.16(b) shall be
limited solely to the out-of-pocket costs and expenses (including reasonable
fees and expenses of outside counsel) incurred by DCC or its subsidiaries in
successfully obtaining dismissal or other favorable disposition of any such
suits, claims or proceedings but shall not include the amounts of any settlement
payments, judgments or other payments of any type.

          Section 6.17  1989 Stock Acquisition Agreement.  Notwithstanding
Section 10.1 of the 1989 Stock Acquisition Agreement, dated as of July 17, 1989
among the Company, RH Acquisition Corp. and DCC (the "1989 Stock Acquisition
Agreement"), Section 7.23 of the 1989 Stock Acquisition Agreement is hereby
waived by the Company and DCC and shall be of no further effect from and after
the purchase of the Dow Shares by Parent, Acquisition or their affiliates;
provided, however, that nothing herein shall be deemed to amend, waive or
supersede any other provision of the 1989 Stock Acquisition Agreement,
including, without limitation, Section 7.18 and Section 7.19 thereof.




                                      52
<PAGE>
 



                                  ARTICLE VII

                   CONDITIONS TO CONSUMMATION OF THE MERGER


          Section 7.1  Conditions to the Company's, Parent's and Acquisition's
Obligation to Effect the Merger.  The respective obligations of the Company,
Parent and Acquisition to effect the Merger are subject to the satisfaction at
or prior to the Effective Time of the following conditions:

          (a)  this Agreement shall have been adopted by the affirmative vote of
the stockholders of the Company by the requisite vote in accordance with
Delaware Law;

          (b)  any waiting period applicable to the Merger under the HSR Act, EC
Merger Regulation and the Canadian Competition Act shall have terminated or
expired;

          (c)  no statute, rule, regulation, executive order, decree, ruling,
injunction or other order shall have been enacted, entered, promulgated or
enforced by any court or governmental or supranational authority of competent
jurisdiction within the United States or the European Community which prohibits
the Merger or makes the Merger illegal; and

          (d)  Acquisition, Parent or their affiliates shall have purchased
the Dow Shares.


                                 ARTICLE VIII

                        TERMINATION; AMENDMENT; WAIVER


          Section 8.1  Termination.  This Agreement may be terminated and the
Merger may be abandoned at any time prior to the Effective Time, notwithstanding
approval thereof by the stockholders of the Company:

          (a)  by mutual written consent of Parent, Acquisition, DCC and
the Company;

          (b)  by Parent, DCC or the Company if any court or governmental or
supranational authority of




                                      53
<PAGE>
 



competent jurisdiction within the United States or the European Community shall
have issued an order, decree or ruling or taken any other action restraining,
enjoining or otherwise prohibiting the Merger and such order, decree, ruling or
other action shall have become final and nonappealable;

          (c)   by Parent, DCC or the Company, at any time after January 31,
1996, if the Merger shall not have occurred by such date; provided, that the
right to terminate this Agreement under this subparagraph (c) shall not be
available to any party whose failure to fulfill any obligation under this
Agreement has been the cause or resulted in the failure of the Merger to have
occurred by such date; provided, further, that no party hereto shall have the
right to terminate this Agreement under this subparagraph (c) if Acquisition,
Parent or their affiliates shall have acquired the Dow Shares;

          (d)  by Parent, at any time prior to the purchase by Acquisition,
Parent or their affiliates of the Dow Shares, if (i) there shall have been a
breach of any representation or warranty of the Company contained herein or of
Dow contained in the Stock Purchase Agreement which would have a Material
Adverse Effect or prevent the consummation of the Merger or the transactions
contemplated by the Stock Purchase Agreement, (ii) there shall have been a
breach of any covenant or agreement of the Company or DCC contained herein or of
Dow contained in the Stock Purchase Agreement which would have a Material
Adverse Effect or prevent the consummation of the Merger or the transactions
contemplated by the Stock Purchase Agreement, which shall not have been cured
prior to two business days following notice of such breach, or (iii) the Board
shall have withdrawn or modified in a manner adverse to Parent its approval or
recommendation of this Agreement, the Merger or the transactions contemplated by
the Stock Purchase Agreement or shall have recommended, or the Company shall
have entered into an agreement providing for, an Acquisition Proposal, or the
Board shall have resolved to do any of the foregoing;

          (e)  by DCC if Acquisition fails to purchase the Dow Shares in
violation of Acquisition's obligations under the Stock Purchase Agreement; or




                                      54
<PAGE>
 



          (f)  at any time prior to the purchase by Acquisition, Parent or their
affiliates of the Dow Shares, by the Company, DCC or Parent in the event the
Stock Purchase Agreement shall have been terminated by the mutual written
consent of the parties thereto.

          Section 8.2  Effect of Termination.  In the event of the termination
and abandonment of this Agreement pursuant to Section 8.1, this Agreement shall
forthwith become void and have no effect, without any liability on the part of
any party hereto, other than the provisions of this Section 8.2 and Section 8.3.
The termination of this Agreement shall not relieve any party from liability for
any breach of this Agreement.

          Section 8.3  Fees and Expenses.  Each party shall bear its own
expenses and costs in connection with this Agreement and the transactions
contemplated hereby.

          Section 8.4  Amendment.  Subject to Section 6.2(c), this Agreement may
be amended by action taken by the Company, DCC, Parent and Acquisition at any
time before or after adoption of the Merger by the stockholders of the Company
but, after any such approval, no amendment shall be made which decreases the
Merger Consideration or changes the form thereof or which adversely affects the
rights of the Company's stockholders hereunder without the approval of such
stockholders.  This Agreement may not be amended except by an instrument in
writing signed on behalf of each of the parties hereto.

          Section 8.5  Extension; Waiver.  Subject to Section 6.2(c), at any
time prior to the Effective Time, the Company and DCC, on the one hand, and
Parent and Acquisition, on the other hand, may (i) extend the time for the
performance of any of the obligations or other acts of the other party, (ii)
waive any inaccuracies in the representations and warranties of the other party
contained herein or in any document, certificate or writing delivered pursuant
hereto, or (iii) waive compliance by the other party with any of the agreements
or conditions contained herein.  Any agreement on the part of any party hereto
to any such extension or waiver shall be valid only if set forth in an
instrument in writing signed on behalf of such party.  The failure of any party
hereto to assert any of its rights hereunder shall not constitute a waiver of
such rights.




                                      55
<PAGE>
 



                                  ARTICLE IX

                                 MISCELLANEOUS


          Section 9.1  Nonsurvival of Representations and Warranties.  The
representations and warranties made herein shall not survive beyond the purchase
by Acquisition, Parent or their affiliates of the Dow Shares.  The covenants and
agreements herein shall survive in accordance with their respective terms.

          Section 9.2  Entire Agreement; Assignment.  This Agreement (including
the Schedules hereto), the Stock Purchase Agreement and the Confidentiality
Agreement (i) constitute the entire agreement among the parties hereto with
respect to the subject matter hereof and supersede all other prior agreements
and understandings, both written and oral, among the parties with respect to the
subject matter hereof and (ii) shall not be assigned by operation of law or
otherwise; provided that Acquisition may assign its rights and obligations in
whole or in part to any direct subsidiary of Parent (provided that such
transferee agrees in writing to be bound by this Agreement), but no such
assignment shall relieve Acquisition of its obligations hereunder if such
assignee does not perform such obligations.

          Section 9.3  Notices.  All notices, requests, claims, demands and
other communications hereunder shall be in writing and shall be given (and shall
be deemed to have been duly given upon receipt) by delivery in person, by
facsimile or by registered or certified mail (postage prepaid, return receipt
requested), to the other party as follows:

          if to Parent or Acquisition:

               Hoechst Corporation
               Route 202-206
               P.O. Box 2500
               Somerville, New Jersey  08876-1258
               Fax: 908-231-4848
               Attention: Harry R. Benz




                                      56
<PAGE>
 



          with copies to:

               Hoechst AG
               65926 Frankfurt am Main
               Germany
               Fax: 011-49-69-319-113
               Attention: Peter Schuster

               and

               Skadden, Arps, Slate, Meagher & Flom
               919 Third Avenue
               New York, New York  10022
               Fax: 212-735-2000
               Attention: Roger S. Aaron
                              and
                          Franklin M. Gittes

          if to the Company:

               Marion Merrell Dow Inc.
               9300 Ward Parkway
               Kansas City, Missouri  64114
               Fax: 816-966-3805
               Attention: General Counsel

          with copies to:

               Shook, Hardy & Bacon PC
               One Kansas City Place
               1200 Main Street
               Kansas City, Missouri  64105-2118
               Fax: 816-421-5547
               Attention: Jennings J. Newcom
                              and
                          Randall B. Sunberg

               and

               Sullivan & Cromwell
               125 Broad Street
               New York, New York  10004
               Fax:  212-558-3355
               Attention:  Francis J. Aquila




                                      57
<PAGE>
 



          if to DCC, to:

               The Dow Chemical Company
               2030 Dow Center
               Midland, Michigan  48674
               Fax:  517-636-0861
               Attention: Jane M. Gootee


          with a copy to:

               Mayer, Brown & Platt
               190 South LaSalle Street
               Chicago, Illinois  60603-3441
               Fax:  312-701-7711
               Attention:  Scott J. Davis

or to such other address as the person to whom notice is given may have
previously furnished to the other in writing in the manner set forth above.

          Section 9.4  Governing Law.  This Agreement shall be governed by and
construed in accordance with the law of the State of Delaware, without regard to
the principles of conflicts of law thereof.  Each of the parties hereto hereby
irrevocably and unconditionally consents to submit to jurisdiction of the courts
of the State of Delaware and of the United States of America located in the
State of Delaware (the "Delaware Courts") for any litigation arising out of or
relating to this Agreement and the transactions contemplated hereby (and agrees
not to commence any litigation relating thereto except in such Delaware Courts),
waives any objection to the laying of venue of any such litigation in the
Delaware Courts and agrees not to plead or claim in any Delaware Court that such
litigation brought therein has been brought in an inconvenient forum.

          Section 9.5  Parties in Interest.  This Agreement shall be binding
upon and inure solely to the benefit of each party hereto and its successors and
permitted assigns, and, except as provided in Section 6.7 nothing in this
Agreement, express or implied, is intended to or shall confer upon any other
person any rights, benefits or remedies of any nature whatsoever under or by
reason of this Agreement.




                                      58
<PAGE>
 



          Section 9.6  Remedies.  The parties hereto agree that irreparable
damage would occur in the event any provision of this Agreement was not
performed in accordance with the terms hereof and that the parties shall be
entitled to specific performance of the terms hereof, in addition to any other
remedy at law or in equity.  Notwithstanding anything to the contrary contained
herein, the Company's exclusive remedy for Parent's or Acquisition's breach of
Section 6.15 shall be an action for monetary damages.

          Section 9.7  Severability.  The provisions of this Agreement shall be
deemed severable and the invalidity or unenforceability of any provision shall
not affect the validity and enforceability of the other provisions hereof.  If
any provision of this Agreement, or the application thereof to any person or
entity or any circumstance, is invalid or unenforceable, (a) a suitable and
equitable provision shall be substituted therefor in order to carry out, so far
as may be valid and enforceable, the intent and purpose of such invalid and
unenforceable provision and (b) the remainder of this Agreement and the
application of such provision to other persons, entities or circumstances shall
not be affected by such invalidity or unenforceability, nor shall such
invalidity or unenforceability affect the validity or enforceability of such
provision, or the application thereof, in any other jurisdiction.

          Section 9.8  Descriptive Headings.  The descriptive headings herein
are inserted for convenience of reference only and are not intended to be part
of or to affect the meaning or interpretation of this Agreement.

          Section 9.9  Certain Definitions.  For purposes of this Agreement, the
term:

          (a) "affiliate" of a person means a person that directly or
indirectly, through one or more intermediaries, controls, is controlled by, or
is under common control with, the first mentioned person;

          (b) "control" (including the terms "controlled by" and "under common
control with") means the possession, directly or indirectly or as trustee or
executor, of the power to direct or cause the direction of the management
policies of a person, whether through the




                                      59
<PAGE>
 



ownership of stock, as trustee or executor, by contract or credit arrangement or
otherwise;

          (c) "generally accepted accounting principles" shall mean the
generally accepted accounting principles set forth in the opinions and
pronouncements of the Accounting Principles Board of the American Institute of
Certified Public Accountants and statements and pronouncements of the Financial
Accounting Standards Board or in such other statements by such other entity as
may be approved by a significant segment of the accounting profession in the
United States, in each case applied on a basis consistent with the manner in
which the audited financial statements for the fiscal year of the Company ended
December 31, 1994 were prepared;

          (d) "person" means an individual, corporation, partnership,
association, trust, unincorporated organization, other entity or group (as
defined in Section 13(d)(3) of the Exchange Act); and

          (e) "subsidiary" or "subsidiaries" of any person means any
corporation, partnership, joint venture or other legal entity of which such
person (either alone or through or together with any other subsidiary), owns,
directly or indirectly, 50% or more of the stock or other equity interests the
holder of which is generally entitled to vote for the election of the board of
directors or other governing body of such corporation, partnership, joint
venture or other legal entity; provided, that Carderm Capital L.P., a Delaware
limited partnership, shall be deemed a subsidiary of the Company for all
purposes under this Agreement.

          Section 9.10  Counterparts.  This Agreement may be executed in two or
more counterparts, each of which shall be deemed to be an original, but all of
which shall constitute one and the same agreement.




                                      60
<PAGE>
 



          IN WITNESS WHEREOF, each of the parties has caused this Agreement to
be executed on its behalf by its representatives thereunto duly authorized, all
as of the day and year first above written.


                         HOECHST CORPORATION



                         By: /s/ Harry R. Benz
                             -----------------------------------
                             Name:  Harry R. Benz
                             Title: Secretary and Treasurer



                         H PHARMA ACQUISITION CORP.



                         By: /s/ Klaus Schmieder
                             -----------------------------------
                             Name:  Klaus Schmieder
                             Title: Vice President and Treasurer



                         MARION MERRELL DOW INC.



                         By: /s/ Fred W. Lyons, Jr.
                             -----------------------------------
                             Name:  Fred W. Lyons, Jr.
                             Title: Chairman and Chief
                                    Executive Officer



                         THE DOW CHEMICAL COMPANY



                         By: /s/ Enrique C. Falla
                             -----------------------------------
                             Name:  Enrique C. Falla
                             Title: Executive Vice
                                    President and Chief
                                    Financial Officer

<PAGE>
 
                            STOCK PURCHASE AGREEMENT


          THIS STOCK PURCHASE AGREEMENT, dated as of   May 3, 1995, is among
Hoechst Corporation, a Delaware corporation ("Parent"), H Pharma Acquisition
Corp., a Delaware corporation ("Acquisition"), The Dow Chemical Company, a
Delaware corporation ("DCC"), RH Acquisition Corp., a Delaware corporation and a
wholly owned subsidiary of DCC ("RHAC"), and Dow Holdings Inc., a Delaware
corporation and a wholly owned subsidiary of DCC ("DHI").  DCC, RHAC and DHI are
sometimes individually referred to herein as a "Seller" and are sometimes
collectively referred to herein as the "Sellers".

          WHEREAS, simultaneously with the execution and delivery of this
Agreement, Parent, Acquisition, DCC and Marion Merrell Dow Inc., a Delaware
corporation (the "Company"), are entering into an Agreement and Plan of Merger
(the "Merger Agreement"), which provides, among other things, upon the terms and
subject to the conditions thereof, that (i) Acquisition will be merged with and
into the Company in accordance with the General Corporation Law of the State of
Delaware ("Delaware Law") and (ii) each share of common stock, par value $0.10
per share, of the Company (the "Shares"), issued and outstanding immediately
prior to the Effective Time (as defined in the Merger Agreement) will, except as
otherwise expressly provided in the Merger Agreement, be converted into the
right to receive the Merger Consideration (as defined in the Merger Agreement);

          WHEREAS, each Seller owns the number of Shares (the "Seller's Shares")
set forth on Schedule A hereto opposite the name of such Seller; and

          WHEREAS, in order to induce Parent and Acquisition to enter into the
Merger Agreement, each Seller has agreed to enter into this Agreement.

          NOW, THEREFORE, in consideration of the foregoing and the mutual
covenants and agreements herein contained, and intending to be legally bound
hereby, Parent, Acquisition and the Sellers hereby agree as follows.


<PAGE>
 
          Section 1.  Capitalized Terms.  Capitalized terms used but not defined
herein shall have the meanings assigned to such terms in the Merger Agreement.

          Section 2.  Representations and Warranties of Sellers.  Each Seller
represents and warrants to Parent and Acquisition as follows:

          (a)  Such Seller is a corporation duly organized, validly existing and
in good standing under the laws of the jurisdiction of its incorporation.

          (b)  Such Seller has all necessary corporate power and authority to
execute and deliver this Agreement, to perform its obligations hereunder and to
consummate the transactions contemplated hereby.

          (c)  The execution, delivery and performance of this Agreement and the
consummation of the transactions contemplated hereby have been duly and validly
authorized by the board of directors of such Seller and the sole stockholder of
RHAC and (indirectly) DHI and no other corporate proceedings on the part of any
Seller are necessary to authorize this Agreement or to consummate the
transactions so contemplated.

          (d)  This Agreement has been duly and validly executed and delivered
by such Seller and constitutes a legal, valid and binding agreement of such
Seller enforceable against such Seller in accordance with its terms.

          (e)  The execution, delivery and performance by such Seller of this
Agreement and the consummation of the transactions contemplated hereby do not
and will not (i) contravene or conflict with the Certificate of Incorporation or
By-Laws of such Seller; (ii) assuming that all consents, authorizations and
approvals contemplated by subsection (f) below have been obtained and all
filings described therein have been made, contravene or conflict with or
constitute a violation of any provision of any law, regulation, judgment,
injunction, order or decree binding upon or applicable to such Seller, any of
its subsidiaries or any of its properties; (iii) conflict with, or result in the
breach or termination of any provision of or constitute a default (with or
without the giving of notice or the lapse of time or both) under, or

                                       2
<PAGE>
 
give rise to any right of termination, cancellation, or loss of any benefit to
which such Seller or any of its subsidiaries is entitled under any provision of
any agreement, contract, license or other instrument binding upon such Seller,
any of its subsidiaries or any of their respective properties, or allow the
acceleration of the performance of, any obligation of such Seller or any of its
subsidiaries under any indenture, mortgage, deed of trust, lease, license,
contract, instrument or other agreement to which such Seller or any of its
subsidiaries is a party or by which such Seller or any of its subsidiaries or
any of their respective assets or properties is subject or bound; or (iv) result
in the creation or imposition of any Lien on any asset of such Seller or any of
its subsidiaries, except in the case of clauses (ii), (iii) and (iv) for any
such contraventions, conflicts, violations, breaches, terminations, defaults,
cancellations, losses, accelerations and Liens which would not individually or
in the aggregate be reasonably expected to prevent the consummation by such
Seller of the transactions contemplated by this Agreement.

          (f)  The execution, delivery and performance by such Seller of this
Agreement and the consummation of the transactions contemplated hereby by such
Seller require no action by or in respect of, or filing with, any governmental
body, agency, official or authority (either domestic or foreign) other than (i)
compliance with any applicable requirements of the HSR Act, the EC Merger
Regulation and the Canadian Competition Act; (ii) compliance with any applicable
requirements of the Exchange Act and state securities, takeover and Blue Sky
laws; (iii) the filing of a notice pursuant to Exon-Florio; and (iv) such
actions or filings which, if not taken or made, would not individually or in the
aggregate be reasonably expected to prevent the consummation by such Seller of
the transactions contemplated by this Agreement.

          (g)  Except as previously disclosed by the Sellers to Parent and
Acquisition, as of the date hereof, there is no action, suit, claim,
investigation or proceeding pending against, or to the knowledge of the Sellers,
threatened against, any Seller or any of its subsidiaries or any of their
respective properties before any court or arbitrator or any administrative,
regulatory or governmental body, or any agency or official which challenges or
seeks to prevent, enjoin, alter or delay

                                       3
<PAGE>
 
the Merger or any of the other transactions contemplated hereby or by the Merger
Agreement. As of the date hereof, none of the Sellers, none of their respective
subsidiaries and none of their respective properties is subject to any order,
writ, judgment, injunction, decree, determination or award which would prevent
or delay the consummation of the transactions contemplated hereby.

          (h)  Such Seller has, and at any Closing (as defined below) hereunder
such Seller will have, good and valid title to such Seller's Shares, free and
clear of any Liens.

          (i)  There are no options or rights to acquire, or any agreements to
which such Seller is a party relating to, such Seller's Shares, other than this
Agreement.

          (j)  The transfer of such Seller's Shares hereunder to Acquisition
will transfer to Acquisition good and valid title to such Seller's Shares, free
and clear of any Liens.

          (k)  The Seller's Shares described in Schedule A represent all of the
Shares beneficially owned (within the meaning of Rule 13d-3 under the Exchange
Act) by DCC.

          (l)  DCC owns, directly or indirectly, all of the outstanding shares
of capital stock of RHAC and DHI, free and clear of any Liens.

          Section 3.  Representations and Warranties of Parent and Acquisition.
Each of Parent and Acquisition represents and warrants to the Sellers as
follows:

          (a)  Each of Parent and Acquisition is a corporation duly organized,
validly existing and in good standing under the laws of the jurisdiction of its
incorporation.

          (b)  Each of Parent and Acquisition has all necessary corporate power
and authority to execute and deliver this Agreement, to perform its obligations
hereunder and to consummate the transactions contemplated hereby.

          (c)  The execution, delivery and performance of this Agreement and the
consummation of the transactions 

                                       4
<PAGE>
 
contemplated hereby have been duly and validly authorized by the board of
directors of each of Parent and Acquisition and no other corporate proceedings
on the part of Parent or Acquisition are necessary to authorize this Agreement
or to consummate the transactions so contemplated.

          (d)  This Agreement has been duly and validly executed and delivered
by each of Parent and Acquisition and constitutes a legal, valid and binding
agreement of each of Parent and Acquisition enforceable against each of Parent
and Acquisition in accordance with its terms.

          (e)  The execution, delivery and performance by Parent and Acquisition
of this Agreement and the consummation of the transactions contemplated hereby
do not and will not (i) contravene or conflict with the Certificate of
Incorporation or By-Laws of Parent or Acquisition; (ii) assuming that all
consents, authorizations and approvals contemplated by subsection (f) below have
been obtained and all filings described therein have been made, contravene or
conflict with or constitute a violation of any provision of any law, regulation,
judgment, injunction, order or decree binding upon or applicable to Parent,
Acquisition, any of their respective subsidiaries or any of their respective
properties; (iii) conflict with, or result in the breach or termination of any
provision of or constitute a default (with or without the giving of notice or
the lapse of time or both) under, or give rise to any right of termination,
cancellation, or loss of any benefit to which Parent, Acquisition or any of
their respective subsidiaries is entitled under any provision of any agreement,
contract, license or other instrument binding upon Parent, Acquisition, any of
their respective subsidiaries or any of their respective properties, or allow
the acceleration of the performance of, any obligation of Parent, Acquisition or
any of their respective subsidiaries under any indenture, mortgage, deed of
trust, lease, license, contract, instrument or other agreement to which Parent
or Acquisition is a party or by which Parent, Acquisition, any of their
respective subsidiaries or any of their respective assets or properties is
subject or bound; or (iv) result in the creation or imposition of any Lien on
any asset of Parent, Acquisition, or any of their respective subsidiaries except
in the case of clauses (ii), (iii) and (iv) for any such contraventions,
conflicts, violations, breaches, termina-

                                       5
<PAGE>
 
tions, defaults, cancellations, losses, accelerations and Liens which would not
individually or in the aggregate be reasonably expected to prevent the
consummation by Parent or Acquisition of the transactions contemplated by this
Agreement.

          (f)  The execution, delivery and performance by Parent and Acquisition
of this Agreement and the consummation of the transactions contemplated hereby
by Parent and Acquisition require no action by or in respect of, or filing with,
any governmental body, agency, official or authority (either domestic or
foreign) other than (i) compliance with any applicable requirements of the HSR
Act, the EC Merger Regulation and the Canadian Competition Act; (ii) compliance
with any applicable requirements of the Exchange Act and state securities,
takeover and Blue Sky laws; (iii) the filing of a notice pursuant to Exon-
Florio; and (iv) such actions or filings which, if not taken or made, would not
individually or in the aggregate be reasonably expected to prevent the
consummation by Parent and Acquisition of the transactions contemplated by this
Agreement.

          (g)  Except as previously disclosed by Parent and Acquisition to
Sellers, as of the date hereof, there is no action, suit, claim, investigation
or proceeding pending against, or to the knowledge of Parent and Acquisition,
threatened against, Parent, Acquisition, any of their respective subsidiaries or
any of their respective properties before any court or arbitrator or any
administrative, regulatory or governmental body, or any agency or official which
challenges or seeks to prevent, enjoin, alter or delay the Merger or any of the
other transactions contemplated hereby or by the Merger Agreement.  As of the
date hereof, none of Parent, Acquisition, any of their respective subsidiaries
or any of their respective properties is subject to any order, writ, judgment,
injunction, decree, determination or award which would prevent or delay the
consummation of the transactions contemplated hereby.

          Section 4.  Purchase of Seller's Shares by Acquisition; Dividends.  As
soon as practicable following the satisfaction or waiver of all of the
conditions set forth in Section 10 hereof, but, subject to the following
sentence, in no event more than three business days following such satisfaction
or waiver, Acquisition shall 

                                       6

<PAGE>
 
purchase all of each Seller's Shares, at a purchase price of $25.75 per Share in
cash (the "Purchase Price"). The closing of such purchase and sale (the
"Closing") of the Seller's Shares shall take place at such time and on such
business day as Acquisition may designate (the "Closing Date") by notice to
Sellers; provided, that the Closing shall not take place during any period
beginning the day following the New York Stock Exchange "ex-dividend" date and
ending on the corresponding record date with respect to a regular quarterly cash
dividend on the Shares; provided, further, that, if the Closing is delayed as
set forth in the immediately preceding proviso, then the Closing shall take
place on the first business day following such record date. The Closing shall
occur at the office of Skadden, Arps, Slate, Meagher & Flom, 919 Third Avenue,
New York, New York 10022, or such other place as the parties may mutually agree.
The parties further agree that if Acquisition acquires the Seller's Shares on or
before the New York Stock Exchange "ex-dividend" date in respect of any regular
quarterly cash dividend paid in respect of the Shares, then, whether or not such
Seller's Shares are transferred of record to Acquisition on or before the
corresponding record date, the dividend payable to holders of record on such
record date shall be for the account of Acquisition and not the Sellers. The
foregoing shall not limit the remedies of Parent and Acquisition, on the one
hand, or the Sellers, on the other hand, in the event that the other parties
hereto fail to effect the Closing in violation of their obligations hereunder.

          Section 5.  Transfer of Shares.  At the Closing, and subject to the
satisfaction or waiver of the conditions set forth in Section 10 of this
Agreement, each of the Sellers will sell, transfer and deliver such Seller's
Shares to Acquisition (in proper form for transfer) and Acquisition will
purchase such Shares and wire transfer to the Sellers (to such accounts as the
Sellers shall specify on at least two days notice) immediately available funds
representing the aggregate Purchase Price for such Seller's Shares, without
deduction or setoff of any kind, including, without limitation, any deduction
for any stock transfer tax or similar governmental transfer tax. Acquisition
shall bear responsibility for any stock transfer tax or similar governmental
transfer tax, arising out of the transfer of each Seller's Shares, but shall not
have any responsibility whatsoever for any

                                       7
<PAGE>
 
other taxes imposed by law on any of the Sellers. At the Closing and thereafter,
each Seller will, upon request of Acquisition, execute and deliver all
additional documents reasonably deemed by Acquisition to be necessary,
appropriate or desirable to effect, complete and evidence the sale, assignment
and transfer of such Seller's Shares pursuant to this Agreement.

          Section 6.  Anti-Dilution Adjustments.  In the event of any change in
the number of Shares outstanding by recapitalization, declaration of a stock
split or combination or payment of a stock dividend or the like, the number of
Shares to be transferred to Acquisition and the per Share payments to be made to
the Sellers shall be adjusted appropriately.

          Section 7.  Covenants. Except as provided for herein, each Seller
agrees not to (either directly or indirectly):

          (a)  sell, transfer, pledge, assign, hypothecate or otherwise dispose
of, or enter into any contract, option or other arrangement or understanding
with respect to the sale, transfer, pledge, assignment, hypothecation or other
disposition of such Seller's Shares (including, without limitation, through the
disposition or transfer of control of another person);

          (b)  grant any proxies with respect to such Seller's Shares, deposit
such Seller's Shares into a voting trust or enter into a voting agreement with
respect to any of such Seller's Shares; or

          (c)  take any action which would make any representation or warranty
of such Seller herein untrue or incorrect in any material respect.

          Section 8.  No Solicitation.  (a) The Sellers will immediately cease
any existing discussions or negotiations with any third parties conducted prior
to the date hereof with respect to any Acquisition Proposal (as defined below).
The Sellers shall not, directly or indirectly, through any officer, director,
employee, representative or agent or any of their respective subsidiaries, (i)
solicit, initiate, or encourage any inquiries or proposals that constitute, or
would lead to, a proposal or offer for a merger, consolidation, business 
combina-

                                       8
<PAGE>
 
tion, sale of substantial assets, sale of a substantial percentage of shares of
capital stock (including without limitation by way of a tender offer) or similar
transactions involving the Company or any of its subsidiaries, other than the
transactions contemplated by this Agreement and the Merger Agreement (any of the
foregoing inquiries or proposals being referred to in this Agreement as an
"Acquisition Proposal"), (ii) engage in negotiations or discussions concerning,
or provide any non-public information to any person or entity relating to, any
Acquisition Proposal, or (iii) agree to, approve or recommend any Acquisition
Proposal; provided, that the Sellers shall not be deemed to have breached their
obligations contained in this Section 8(a) by reason of the Company's taking any
action permitted by the proviso to Section 6.10(a) of the Merger Agreement.

          (b)  The Sellers shall notify Parent immediately (and no later than 24
hours) after receipt by any Seller of any Acquisition Proposal or any request
for non-public information in connection with an Acquisition Proposal or for
access to the properties, books or records of the Company by any person or
entity that informs such party that it is considering making, or has made, an
Acquisition Proposal.  Such notice shall be made orally and shall indicate in
reasonable detail the identity of the offeror and the terms and conditions of
such proposal, inquiry or contract.

          Section 9.  Voting Agreement; Proxy.

          (a)  For so long as this Agreement is in effect, Sellers shall vote,
or cause to be voted, all of their respective Seller's Shares in favor of the
approval and adoption of the Merger Agreement and the transactions contemplated
thereby.

          (b)  For so long as this Agreement is in effect, in any meeting of the
stockholders of the Company, however called, and in any action by consent of
the stockholders of the Company, Sellers shall vote or cause to be voted all of
their respective Seller's Shares:  (i) against any action or agreement that
would result in a breach in any material respect of any covenant, representation
or warranty or any other obligation of the Company or DCC under the Merger
Agreement or of Sellers under this Agreement; and (ii) against any action or
agreement

                                       9
<PAGE>
 
that would impede, interfere with or discourage the transactions contemplated by
the Merger Agreement, including, without limitation: (1) any extraordinary
corporate transaction, such as a merger, reorganization or liquidation involving
the Company or any of its subsidiaries, (2) a sale or transfer of a material
amount of assets of the Company or any of its subsidiaries or the issuance of
securities by the Company or any of its subsidiaries, (3) any change in the
Board (other than as contemplated by the Merger Agreement), (4) any change in
the present capitalization or dividend policy of the Company (other than as
contemplated by the Merger Agreement) or (5) any other material change in the
Company's corporate structure or business.

          (c)  Upon receipt of the Purchase Price as provided in Section 5
hereof, each Seller shall grant Acquisition an irrevocable proxy and irrevocably
appoint Acquisition or its designees, with full power of substitution, its
attorney and proxy to vote all such Seller's Shares at any meeting of the
stockholders of the Company however called, or in connection with any action by
written consent by the stockholders of the Company.  Each Seller acknowledges
and agrees that such proxy, if and when given, will be coupled with an interest,
will be irrevocable and shall not be terminated by operation of law or otherwise
upon the occurrence of any event and that no subsequent proxies will be given
(and if given will not be effective).

          Section 10.  Conditions.  (a) The obligation of Acquisition to
purchase the Seller's Shares hereunder shall be subject to the satisfaction or
waiver at or prior to the Closing of each of the following conditions:

          (i)  any waiting period applicable to the purchase and sale of the
Seller's Shares pursuant to this Agreement under the HSR Act, the EC Merger
Regulation and the Canadian Competition Act shall have terminated or expired;

          (ii)  either (A) the Committee on Foreign Investment in the United
States shall have determined not to investigate the transactions contemplated by
this Agreement or the Merger Agreement under Exon-Florio (either by action or
inaction) or (B) if such Committee shall have determined to make such an
investigation, such

                                       10
<PAGE>
 
investigation shall have been completed or the President shall have determined
(by action or inaction) not to take any action under Exon-Florio with respect to
the transactions contemplated by this Agreement or the Merger Agreement;

          (iii)  no statute, rule, regulation, executive order, decree, ruling,
injunction or other order shall have been enacted, entered, promulgated or
enforced by any court or governmental or supranational authority of competent
jurisdiction within the United States or the European Community (including in
connection with obtaining termination of applicable waiting periods under the
HSR Act and the EC Merger Regulation) which (x) prohibits or makes illegal the
sale of any Seller's Shares pursuant to this Agreement or (y) with respect to
antitrust or similar competition law matters, would have a material adverse
effect on (A) the United States business and operations of the Company and its
subsidiaries and the United States pharmaceutical business and operations of
Parent and its affiliates, taken as a whole or (B) the European business and
operations of the Company and its subsidiaries and the European pharmaceutical
business and operations of Parent and its affiliates, taken as a whole (it being
agreed that the meaning of "material adverse effect" for purposes of this clause
(y) shall be consistent with discussions among the parties hereto and their
respective counsel);

          (iv)  there shall not have occurred any governmental action (such as
the declaration of a banking moratorium or a prohibition on the export of funds)
which prevents Parent and Acquisition from obtaining the funds necessary to pay
the aggregate Purchase Price hereunder (it being agreed that in such event
Parent and Acquisition shall use their reasonable best efforts to obtain
alternative sources of funds as soon as practicable, and that this condition is
not intended to include governmental actions that merely make it more expensive
for Parent and Acquisition to obtain the funds necessary to pay the aggregate
Purchase Price hereunder);

          (v)  the Sellers shall have performed in all material respects all of
their covenants and agreements under this Agreement required to be performed at
or prior to the Closing, and each of DCC and the Company shall have performed in
all material respects all of its

                                       11
<PAGE>
 
covenants and agreements under the Merger Agreement required to be performed at
or prior to the Closing hereunder; provided, that with respect to such covenants
and agreements of the Company, the foregoing condition shall be deemed satisfied
so long as no failure to perform any such covenant or agreement shall have had
or would have a Material Adverse Effect and that the existence of any remedy
under Section 6.11 of the Merger Agreement shall not be a condition to
Acquisition's obligation to purchase the Sellers Shares hereunder;

          (vi)  the representations and warranties of the Sellers set forth in
this Agreement and of DCC set forth in the Merger Agreement and in all other
agreements entered into in connection with the transactions contemplated hereby
which are qualified as to materiality shall be true and correct and the
representations and warranties of the Sellers set forth in this Agreement and of
DCC set forth in the Merger Agreement and such other agreements which are not so
qualified shall be true and correct in all material respects, in each case as of
the date when made and (except in the case of any representation and warranty
made as of a specified date) as of the date of the Closing as if such
representations and warranties were made on such date; provided, that the truth
or correctness of the representations set forth in Section 4.5 of the Merger
Agreement shall not be a condition to Acquisition's obligation to purchase the
Seller's Shares hereunder; and

          (vii)  the representations and warranties of the Company set forth in
the Merger Agreement shall be true and correct as of the date when made and
(except in the case of any representation and warranty made as of a specified
date) as of the date of the Closing as if such representations and warranties
were made on such date; provided, that the foregoing condition shall be deemed
satisfied so long as no failure to be so true and correct shall have had or
would have a Material Adverse Effect.

          (b)  The obligation of each Seller to sell such Seller's Shares
hereunder shall be subject to the satisfaction or waiver at or prior to the
Closing of each of the following conditions:

          (i)  any waiting period applicable to the purchase and sale of the
Seller's Shares pursuant to this 

                                       12
<PAGE>
 
Agreement under the HSR Act, the EC Merger Regulation and the Canadian
Competition Act shall have terminated or expired;

          (ii)  either (A) the Committee on Foreign Investment in the United
States shall have determined not to investigate the transactions contemplated by
this Agreement or the Merger Agreement under Exon-Florio (either by action or
inaction) or (B) if such Committee shall have determined to make such an
investigation, such investigation shall have been completed or the President
shall have determined (by action or inaction) not to take any action under Exon-
Florio with respect to the transactions contemplated by this Agreement or the
Merger Agreement;

          (iii)  no statute, rule, regulation, executive order, decree, ruling,
injunction or other order shall have been enacted, entered, promulgated or
enforced by any court or governmental or supranational authority of competent
jurisdiction within the United States or the European Community which prohibits
or makes illegal the sale of any Seller's Shares pursuant to this Agreement;

          (iv)  Parent and Acquisition shall have performed in all material
respects all of their covenants and agreements under this Agreement and under
the Merger Agreement required to be performed at or prior to the Closing;
provided, that the foregoing condition shall be deemed satisfied so long as
Acquisition is ready and able to purchase each Seller's Shares pursuant to this
Agreement;

          (v)  the representations and warranties of Parent and Acquisition set
forth in this Agreement and in the Merger Agreement which are qualified as to
materiality shall be true and correct and which are not so qualified shall be
true and correct in all material respects, in each case as of the date when made
and (except in the case of any representation and warranty made as of a
specified date) as of the date of the Closing as if such representations and
warranties were made on such date; provided, that the foregoing condition shall
be deemed satisfied so long as Acquisition is ready and able to purchase each
Seller's Shares pursuant to this Agreement; and

                                       13
<PAGE>
 
          (vi) the Company shall have performed its obligations under Section
6.14 of the Merger Agreement required to be performed effective as of the
Closing; provided, that if such obligations have not been so performed, Parent
agrees to cause such performance within two business days following the Closing
and the foregoing condition shall be deemed satisfied.

          Section 11.  Public Announcements.  Parent and Acquisition, on the one
hand, and DCC on behalf of the Sellers, on the other hand, will consult with
each other before issuing any press release with respect to the transactions
contemplated by this Agreement and the Merger Agreement, and shall not issue
any such press release prior to such consultation, except as may be required by
applicable law or by applicable rules of any securities exchange.

          Section 12.  Specific Performance.  The parties hereto agree that
irreparable damage would occur in the event any provision of this Agreement was
not performed in accordance with the terms hereof and that the parties shall be
entitled to specific performance of the terms hereof, in addition to any other
remedy at law or in equity.

          Section 13.  Indemnification.  The Sellers, on the one hand, and
Parent and Acquisition, on the other hand, in connection with the transactions
contemplated herein, shall indemnify and hold the other harmless from and
against any and all losses, damages, claims, liabilities or obligations with
respect to (i) any breach of any representation, warranty or agreement of the
other party contained in this Agreement and (ii) any brokerage fees, commissions
or finders' fees payable on the basis of any action taken by the other party or
any of its affiliates.

          Section 14.  Expenses.  Each party shall bear its own expenses and
costs in connection with this Agreement and the transactions contemplated
hereby.

          Section 15.  Nonsurvival of Representations and Warranties; Agreements
Joint and Several. None of the representations and warranties made by the
Sellers, Parent or Acquisition in this Agreement shall survive the Closing
hereunder; provided, that the representations and warranties contained in
Section 2(h) and Section 2(j)

                                       14
<PAGE>
 
shall survive indefinitely following the Closing.  The covenants
and agreements made herein shall survive in accordance with their respective
terms.  Notwithstanding anything contained herein to the contrary, the
representations, warranties and agreements made in this Agreement by the
Sellers, on the one hand, and Parent and Acquisition, on the other hand, shall
be joint and several.

          Section 16.  Amendment; Assignment.  This Agreement may not be
modified, amended, altered or supplemented except upon the execution and
delivery of a written agreement executed by the parties hereto.  No party to
this Agreement may assign any of its rights or obligations under this Agreement
without the prior written consent of the other parties except that the rights
and obligations of Acquisition may be assigned by Acquisition to Parent or any
of Parent's other wholly owned subsidiaries (provided such transferee agrees in
writing to be bound under this Agreement), but no such transfer shall relieve
Acquisition of its obligations hereunder if such transferee does not perform
such obligations.

          Section 17.  Parties in Interest.  This Agreement shall be binding
upon and inure solely to the benefit of each party hereto and its successors and
permitted assigns, and nothing in this Agreement, express or implied, is
intended to or shall confer upon any other person any rights, benefits or
remedies of any nature whatsoever.

          Section 18.  Notices.  All notices, requests, claims, demands and
other communications hereunder shall be in writing and shall be given (and shall
be deemed to have been duly given upon receipt) by delivery in person, by
facsimile or by registered or certified mail (postage prepaid, return receipt
requested), to the other party as follows:

          (a)  If to Parent or Acquisition, to:
               Hoechst Corporation
               Route 202-206
               P.O. Box 2500
               Somerville, New Jersey  08876-1258
               Fax:  908-231-4848
               Attention: Harry R. Benz

                                       15
<PAGE>
 
               with copies to:

               Hoechst AG
               65926 Frankfurt am Main
               Germany
               Fax: 011-49-69-319-113
               Attention: Peter Schuster

               and

               Skadden, Arps, Slate, Meagher & Flom
               919 Third Avenue
               New York, New York  10022
               Fax:  212-735-2000
               Attention:     Roger S. Aaron
                                    and
                              Franklin M. Gittes

          (b)  If to the Sellers, to:

               The Dow Chemical Company
               2030 Dow Center
               Midland, Michigan  48674
               Fax:  517-636-0861
               Attention: Jane M. Gootee

               with a copy to:

               Mayer, Brown & Platt
               190 South LaSalle Street
               Chicago, Illinois  60603-3441
               Fax:  312-701-7711
               Attention:  Scott J. Davis

or to such other address as the person to whom notice is given may have
previously furnished to the other in writing in the manner set forth above.

          Section 19.  Reasonable Best Efforts.  Subject to the terms and
conditions herein provided, each of the parties hereto agrees to use its
reasonable best efforts to take, or cause to be taken, all actions, and to do,
or cause to be done, all things reasonably necessary, proper or advisable under
applicable laws and regulations to consummate and make effective the
transactions contemplated by this Agreement. Without limiting the generality of
the foregoing, the parties hereto shall cooperate

                                       16
<PAGE>
 
with one another (i) in determining whether action by or in respect
of, or filing with, any governmental body, agency, official or authority (either
domestic or foreign) is required, proper or advisable or any actions, consents,
waivers or approvals are required to be obtained from parties to any contracts,
in connection with the transactions contemplated by this Agreement and (ii) in
seeking timely to obtain any such actions, consents, waivers or to make any such
filings.  In addition, Parent and Acquisition shall use their reasonable best
efforts to take such action as may be required by any governmental or
supranational authority of competent jurisdiction within the United States or
the European Community in order to resolve any objections such authority may
have to the transactions contemplated hereby under applicable antitrust laws;
provided, that the foregoing shall not obligate Parent or Acquisition to take
any action which would have a material adverse effect on (A) the United States
business and operations of the Company and its subsidiaries and the United
States pharmaceutical business and operations of Parent and its affiliates,
taken as a whole or (B) the European business and operations of the Company and
its subsidiaries and the European pharmaceutical business and operations of
Parent and its affiliates, taken as a whole (it being agreed that the meaning of
"material adverse effect" for purposes of this proviso shall be consistent with
discussions among the parties and their respective counsel).  In case at any
time after the Closing any further action is necessary or desirable to carry out
the purposes of this Agreement, the proper officers and directors of each party
hereto shall take all such necessary action.

          Section 20.  Governing Law.  This Agreement shall be governed by and
construed in accordance with the law of the State of Delaware, without regard to
the principles of conflicts of law thereof.

          Section 21.  Termination.  This Agreement may be terminated at any
time by mutual written consent of the parties hereto.  Upon the termination of
the Merger Agreement in accordance with its terms, this Agreement shall
forthwith terminate without any action by any of the parties hereto. No such
termination shall relieve any party from liability for any breach of this
Agreement.

                                       17
<PAGE>
 
          Section 22.  Severability.  The provisions of this Agreement shall be
deemed severable and the invalidity or unenforceability of any provision shall
not affect the validity and enforceability of the other provisions hereof.  If
any provision of this Agreement, or the application thereof to any person or
entity or any circumstance, is invalid or unenforceable, (a) a suitable and
equitable provision shall be substituted therefor in order to carry out, so far
as may be valid and enforceable, the intent and purpose of such invalid and
unenforceable provision and (b) the remainder of this Agreement and the
application of such provision to other persons, entities or circumstances shall
not be affected by such invalidity or unenforceability, nor shall such
invalidity or unenforceability affect the validity or enforceability of such
provision, or the application thereof, in any other jurisdiction.

          Section 23.  Entire Agreement.  This Agreement constitutes the entire
agreement among the parties hereto with respect to the subject matter hereof and
supersedes all other prior agreements and understandings, both written and
oral, among the parties with respect to the subject matter hereof.

          Section 24.  Descriptive Headings.  The descriptive headings herein
are inserted for convenience of reference only and are not intended to be part
of or to affect the meaning or interpretation of this Agreement.

          Section 25.  Consent to Jurisdiction.  Each of the parties hereto
hereby irrevocably and unconditionally consents to submit to jurisdiction of the
courts of the State of Delaware and of the United States of America located in
the State of Delaware (the "Delaware Courts") for any litigation arising out of
or relating to this Agreement and the transactions contemplated hereby (and
agrees not to commence any litigation relating thereto except in such Delaware
Courts), waives any objection to the laying of venue of any such litigation in
the Delaware Courts and agrees not to plead or claim in any Delaware Court that
such litigation brought therein has been brought in an inconvenient forum.

          Section 26.  Certain Definitions.  For purposes of this Agreement, the
term:

                                       18
<PAGE>
 
          (a) "affiliate" of a person means a person that directly or
indirectly, through one or more intermediaries, controls, is controlled by, or
is under common control with, the first mentioned person;

          (b) "control" (including the terms "controlled by" and "under common
control with") means the possession, directly or indirectly or as trustee or
executor, of the power to direct or cause the direction of the management
policies of a person, whether through the ownership of stock, as trustee or
executor, by contract or credit arrangement or otherwise;

          (c) "person" means an individual, corporation, partnership,
association, trust, unincorporated organization, other entity or group (as
defined in Section 13(d)(3) of the Exchange Act); and

          (d) "subsidiary" or "subsidiaries" of any person means any
corporation, partnership, joint venture or other legal entity of which such
person (either alone or through or together with any other subsidiary), owns,
directly or indirectly, 50% or more of the stock or other equity interests the
holder of which is generally entitled to vote for the election of the board of
directors or other governing body of such corporation, partnership, joint
venture or other legal entity; provided, that the Company and its subsidiaries
shall not be deemed subsidiaries of any of the Sellers for purposes of this
Agreement.

          Section 27.  Counterparts.  This Agreement may be executed in two or
more counterparts, each of which shall be deemed to be an original, but all of
which shall constitute one and the same agreement.

                                       19
<PAGE>
 



          IN WITNESS WHEREOF, each of the parties has caused this Agreement to
be executed on its behalf by its representatives thereunto duly authorized, all
as of the day and year first above written.


                         HOECHST CORPORATION


                         By:  /s/ Harry Benz
                              ------------------------------
                              Name:  Harry Benz
                              Title: Secretary and Treasurer


                         H PHARMA ACQUISITION CORP.


                         By:  /s/ Klaus Schmieder
                              -----------------------------
                              Name:  Klaus Schmieder
                              Title: Vice President and
                                      Treasurer


                         THE DOW CHEMICAL COMPANY


                         By:  /s/ Enrique C. Falla
                              -----------------------------
                              Name:  Enrique C. Falla
                              Title: Executive Vice
                                      President and Chief
                                      Financial Officer


                         RH ACQUISITION CORP.


                         By:  /s/ John C. Lillich
                              ----------------------------
                              Name:  John C. Lillich
                              Title: President


                         DOW HOLDINGS INC.


                         By:  /s/ Enrique C. Falla
                              -----------------------------
                              Name:  Enrique C. Falla
                              Title: President


                                  SCHEDULE A
                                    TO THE
                           STOCK PURCHASE AGREEMENT

          Capitalized terms used in this Schedule A and not otherwise defined in
this Schedule A have the respective meanings assigned to such terms in the
attached Stock Purchase Agreement.


Name of each Seller                      Number of Shares
- -------------------                      ----------------

The Dow Chemical Company                 65,931,690 Shares

RH Acquisition Corp.                     55,934,100 Shares

Dow Holdings Inc.                        75,000,000 Shares
=========================                ==================
Total                                    196,865,790 Shares

<PAGE>
 
                              INDEMNITY AGREEMENT

          This Indemnity Agreement, dated as of May 3, 1995, is between Hoechst
Corporation, a Delaware corporation ("Hoechst"), and The Dow Chemical Company, a
Delaware corporation ("Dow").

          WHEREAS, Dow directly and indirectly owns approximately 71% of the
outstanding common stock of Marion Merrell Dow Inc., a Delaware corporation
("MMD");

          WHEREAS, at the request of MMD, and pursuant to the terms of an
Agreement to Provide Guaranty, dated as of October 7, 1993 (the "Agreement to
Provide Guaranty"), between Dow and MMD, Dow entered into a Dow Guaranty, dated
as of October 8, 1993 (the "Dow Guaranty"), in favor of the Investors (as
defined in the Dow Guaranty) in Carderm Capital L.P., a Delaware limited
partnership in which subsidiaries of MMD hold a controlling interest;

          WHEREAS, Dow, certain subsidiaries of Dow, Hoechst and H Pharma
Acquisition Corp. have entered into a Stock Purchase Agreement dated as of the
date hereof (the "Stock Purchase Agreement"), providing for the purchase by
Hoechst of all of the shares of MMD owned directly or indirectly by Dow; and

          WHEREAS, Hoechst and Dow desire to specify certain arrangements with
respect to the Dow Guaranty.

          NOW, THEREFORE, in consideration of the foregoing and the agreements
herein contained, and intending to be legally bound, Hoechst and Dow agree as
follows:

          Section 1.  Capitalized Terms.  Capitalized terms used but not defined
in this Agreement shall have the meanings assigned to such terms in the Stock
Purchase Agreement.

          Section 2.  Indemnification by Hoechst.   From and after the earlier
of the purchase by Acquisition of the Dow Shares pursuant to the Stock Purchase
Agreement and the Merger (such earlier date being referred to as the
"Indemnification Date"), Hoechst shall indemnify and hold harmless Dow and each
of its subsidiaries, affiliates, directors, officers, employees, agents, and
representatives (collectively, the "Dow Group"), from and against all demands,
claims, actions
<PAGE>
 
or causes of action, assessments, losses, damages, liabilities,
costs and expenses, including, without limitation, interest, penalties and
attorney's fees, disbursements and expenses asserted against, resulting to, or
imposed upon or incurred by any member of the Dow Group, directly or indirectly,
resulting from or arising out of the Dow Guaranty; provided, that, any payments
made by Hoechst to Dow pursuant to this Section 2 shall be net of any payments
made by MMD to Dow pursuant to the Agreement to Provide Guaranty.  Nothing
herein contained shall, or be deemed to, release MMD from its obligations and
covenants under the Agreement to Provide Guaranty or any other agreement
relating to Carderm Capital L.P.

          Section 3.  Termination or Substitution of Dow Guaranty.  From and
after the Indemnification Date, Hoechst shall use its reasonable best efforts,
at its own cost and expense, to terminate the Dow Guaranty or substitute Hoechst
in Dow's stead under the Dow Guaranty, and in any event obtain a full and
unconditional release of liability of Dow under the Dow Guaranty with the
consent of the Investors.

          Section 4.  Guaranty Fee.  On the Indemnification Date, Dow agrees to
pay Hoechst, or its designee, the pro rata portion of the guaranty fee paid to
Dow.  Hoechst's portion of the guaranty fee shall equal the fraction of the
original $1,113,000 guaranty fee, the numerator of which is 2,436 minus the
number of whole days from October 7, 1993 to the Indemnification Date, and the
denominator of which is 2,436.

          Section 5.  Governing Law.  This Agreement shall be governed by and
construed in accordance with the law of the State of Delaware, without regard to
the principles of conflicts of law thereof.  Any suit, action or proceeding
seeking to enforce any provision of, or based on any matter arising out of or in
connection with, this Agreement or the transactions contemplated by this
Agreement may be brought against any of the parties in the United States
District Court for the District of Delaware or any state court sitting in the
City of Wilmington, Delaware, and each of the parties hereby consents to the
exclusive jurisdiction of such courts (and of the appropriate appellate courts)
in any such suit, action or proceeding and waives any objection to venue laid
therein.  Process in any such suit, action or proceeding may be served on any
party anywhere in the world, whether within or without the State of Delaware.
Without limiting the foregoing, each of the parties agrees that service of
process upon such party at the address
referred to below, together with written notice of such service to such party,
shall be deemed effective service of process upon such party.

                                       2
<PAGE>
 
                   Dow:         The Dow Chemical Company
                                2030 Dow Center
                                Midland, Michigan 48674
                                Attn.:  General Counsel

                   Hoechst:     Hoechst Corporation
                                Route 202-206
                                Somerville, NJ 08876-1258
                                Attn:  Treasurer

          Section 6.  Counterparts.  This Agreement may be executed in two or
more counterparts, each of which shall be deemed to be an original, but all of
which shall constitute one and the same agreement.

                                       3
<PAGE>
 
          IN WITNESS WHEREOF, each of the parties has caused this Agreement to
be duly executed on its behalf by their respective authorized representatives as
of the day and year first above written.


                              HOECHST CORPORATION


                              By:    /s/ Harry R. Benz
                                     -----------------
                              Name:  Harry R. Benz
                                     -------------
                              Title:   Secretary and Treasurer
                                     --------------------------


                              THE DOW CHEMICAL COMPANY


                              By:    /s/ Enrique C. Falla
                                     --------------------
                              Name:  Enrique C. Falla
                                     -----------------
                              Title: Executive Vice President
                                     -----------------------------
                                     and Chief Financial Officer
                                     -----------------------------

                                       4

<PAGE>
- -------------------------------------------------------------------------------

 
                            TAX ALLOCATION AGREEMENT



                                     Among


                            The Dow Chemical Company


                              Hoechst Corporation

                                      and


                            Marion Merrell Dow Inc.


                            Dated as of May 3, 1995


- -------------------------------------------------------------------------------
<PAGE>
 
                               TABLE OF CONTENTS
<TABLE>
<CAPTION>
                                                                    Page
<S>                <C>                                              <C>
 
Section 1.         Certain Defined Terms............................  1
    Audit...........................................................  1
    Combined Report.................................................  2
    Combined Reporting..............................................  2
    Combined Return.................................................  2
    Combined Taxes..................................................  2
    Effective Date..................................................  2
    Extended Due Date...............................................  2
    MMD Member Liability............................................  2
    MMD Matter......................................................  3
    Non-Federal Taxes...............................................  3
    Non-Federal Tax Return..........................................  3
    Separate Taxable Income.........................................  3
    Tax Authority...................................................  4
    Tax Returns.....................................................  4
    Taxes...........................................................  4
 
Section  2.        Preparation and Filing of Non-Federal Tax
                   Returns..........................................  4
         2.1.      Non-Federal Tax Returns..........................  4
         2.2.      Consistent Preparation of Combined Returns.......  4
         2.3.      Combined Returns for Periods that Include the
                   Effective Date...................................  5
 
Section  3.        Payment of Taxes.................................  5
         3.1.      Non-Federal Taxes for Combined Returns...........  5
         3.2.      True-up; Combined Taxes..........................  5
 
Section  4.        Redetermination..................................  6
         4.1.      Definition of Redetermination....................  6
         4.2.      Redetermination of Non-Federal Taxes.............  6
 
Section  5.        Audits, Disputes, Etc............................  7
         5.1.      Non-Federal Taxes................................  7
         5.2.      Notification.....................................  7
 
Section  6.        Mutual Cooperation...............................  8
 
Section  7.        Resolution of Certain Conflicts..................  9
 
Section  8.        Tax Returns for Periods Beginning on or After the
                   Effective Date...................................  9
 
Section  9.        Other Taxes......................................  9
 
Section 10.        Statute of Limitations...........................  9
 
Section 11.        Miscellaneous....................................  9
 
</TABLE>

                                       i
<PAGE>
 
<TABLE>
<S>                <C>                                                <C>
    a.             Effectiveness....................................   9
    b.             Entire Agreement.................................  10
    c.             Severability.....................................  10
    d.             Time of Payment..................................  10
    e.             Governing Law....................................  10
    f.             Notices..........................................  10
    g.             Modification or Amendment........................  12
    h.             Successors and Assigns...........................  12
    i.             No Third-Party Beneficiaries.....................  12
    j.             MMD Payments.....................................  12
    k.             Hoechst Payments.................................  12
</TABLE>
Exhibits

Schedule 1(h)
  
                                      ii
<PAGE>
 
     This Tax Allocation Agreement (the "Agreement"), is entered into between
The Dow Chemical Company, a Delaware corporation ("DCC"), Marion Merrell Dow
Inc., a Delaware corporation ("MMD"), and the Hoechst Corporation, a Delaware
corporation ("Hoechst") on May 3, 1995.

                                  WITNESSETH:

     WHEREAS, DCC and certain of its affiliates own outstanding shares of common
stock, par value $0.10 per share, of MMD;

     WHEREAS, MMD and its subsidiaries (hereafter collectively referred to as
the "MMD Group") and DCC and its subsidiaries (excluding the MMD Group (or any
member thereof)) (hereafter collectively referred to as the "DCC Group") file
certain tax returns on a consolidated, combined, or unitary basis;

     WHEREAS, pursuant to the (i) Agreement and Plan of Merger, dated as of May
3, 1995 (the "Merger Agreement"), among MMD, DCC, Hoechst, and H Pharma
Acquisition Corp., a Delaware corporation ("Acquisition"), and (ii) Stock
Purchase Agreement, dated as of May 3, 1995 (the "Stock Purchase Agreement"),
among Parent, Acquisition, DCC, Acquisition Corp., a Delaware corporation and a
wholly-owned subsidiary of DCC, Dow Holdings Inc., a Delaware corporation and a
wholly-owned subsidiary of DCC, the DCC Group will cease to own any outstanding
shares of common stock, par value $0.10 per share, of and will cease to file any
tax returns with the MMD Group (or any members of the MMD Group) on a
consolidated, combined, or unitary basis for any taxable periods beginning after
the Effective Date (as defined herein);

     WHEREAS, it is the intent and desire of the parties hereto to provide for
(i) allocations of certain liabilities for Taxes (as defined herein), (ii) the
preparation and filing of Non-Federal Tax Returns (as defined herein), (iii) the
payment of Non-Federal Taxes (as defined herein), (iv) mutual cooperation
provisions, and (v) certain related matters:

     NOW, THEREFORE, in consideration of the mutual covenants and promises
contained herein, the parties hereto agree as follows:

     Section 1.  Certain Defined Terms.  For purposes of this Agreement, the
following terms shall have the following meanings:

          a. "Audit" includes any audit, assessment of Non-Federal Taxes, other
examination by any Tax Authority (as defined herein), proceeding, or appeal of
such proceeding relating to Non-Federal Taxes, whether administrative or
judicial.

                                       1
<PAGE>
 
          b.  "Combined Report" means any Combined Return where DCC makes all
payments to the appropriate Tax Authority on behalf of all members of the MMD
Group and the DCC Group.

          c. "Combined Reporting" means any Combined Return where the DCC Group
and the MMD Group make separate payments to the appropriate Tax Authority on
each entity's behalf.

          d. "Combined Return" means any Non-Federal Tax Return (including both
Combined Reports and Combined Reporting) that is filed on a consolidated,
combined, or unitary basis between or among (i) the MMD Group (or any member
thereof) and (ii) the DCC Group (or any member thereof).

          e. "Combined Taxes" means all Non-Federal Taxes reported and paid on a
Combined Return that are imposed on a consolidated, combined, or unitary basis
with respect to the assets, earnings, and/or operations of (i) the MMD Group (or
any member thereof) and (ii) the DCC Group (or any member thereof).

          f. "Effective Date" means the earlier of the consummation of the (i)
Merger (as defined in the Merger Agreement) pursuant to the Merger Agreement or
(ii) completion of the acquisition of beneficial ownership of the Shares (as
defined in the Stock Purchase Agreement) pursuant to the Stock Purchase
Agreement.

          g. "Extended Due Date" means with respect to any Non-Federal Tax
Return (including Combined Returns), the extended due date for filing the
relevant Non-Federal Tax Return.

          h. "MMD Member Liability" shall equal, for each Combined Report, (i)
the Separate Taxable Income for each member of the MMD Group that is included in
a Combined Return and has nexus in the jurisdiction for which the Combined
Return is filed divided by (ii) the sum of the Separate Taxable Income for all
members of the MMD Group and the DCC Group that are included in the Combined
Return and have nexus in such jurisdiction multiplied by (iii) the total
Combined Tax for such Combined Report.  Such MMD Member Liability described
above is consistent with the method used in the past in determining such MMD
Member Liability.  A member of the MMD Group will be determined to possess or
lack nexus with a state if either (i) such member was determined by MMD and DCC
to have nexus with the state when the Combined Return in question was filed
prior to the date of the signing of this Agreement or (ii) if a Combined Return
has not been filed as of the date of signing of this Agreement, (a) the member
of the MMD Group is listed as possessing or lacking nexus with respect to a
state on Schedule 1(h) attached hereto; provided, however, unless MMD and DCC
agree that a nexus determination on Schedule 1(h) is materially inaccurate
pursuant

                                      -2-
<PAGE>
 
to Wisconsin Department of Revenue v. William Wrigley, Jr., Co., 112 S. Ct. 2447
(1992) and Pub. L. No. 86-272, or (b) with respect to any state not specified on
Schedule 1(h), MMD and DCC shall, consistent with the past practice used with
respect to the states listed in Schedule 1(h), determine the presence or absence
of nexus pursuant to the general application of Wisconsin Department of Revenue
v. William Wrigley, Jr., Co., 112 S. Ct. 2447 (1992) and Pub. L. No. 86-272,
unless the state determines that such member possesses or lacks nexus with the
state and such determination is upheld in any administrative hearing or Tax
litigation or is not being contested by MMD or DCC.  A member of the DCC Group
will be determined to possess or lack nexus with a state in a manner that is
consistent with past practice and pursuant to the general application of
Wisconsin Department of Revenue v. William Wrigley, Jr. Co., 112 S. Ct. 2447
(1992) and Pub. L. No. 86-272, unless the state determines that such member
possesses or lacks nexus with the state and such determination is upheld in any
administrative hearing or Tax litigation or is not being contested by DCC.

          i. "MMD Matter" shall have the meaning ascribed thereto in Section 5.1
of this Agreement.

          j. "Non-Federal Taxes" includes all state, local, and foreign taxes,
charges, fees, levies, imposts, duties, or other assessments of a similar
nature, including without limitation, ad valorem, alternative or add-on minimum,
capital stock, custom duty, disability, employment, environmental, estimated,
excise, franchise, governmental fee or other like assessment or charge of any
kind whatsoever, gross receipts, income, license, occupation, payroll, premium,
profits, property (including real, personal, and intangible), registration,
sales, severance, social security (or similar), stamp, transfer, unemployment,
use, value-added, windfall profits, withholding, or other tax of any kind
whatsoever, including any interest, penalty, or addition thereto, whether
disputed or not.

          k. "Non-Federal Tax Return" means any return, declaration, statement,
report, schedule, certificate, form, information return, or any other document
(including any related or supporting information), including an amended return,
required to be supplied to, or filed with, a Tax Authority with respect to Non-
Federal Taxes;

          l. "Separate Taxable Income" means, for any Non-Federal jurisdiction,
with respect to each member of the MMD Group and the DCC Group, the taxable
income allocable to such jurisdiction for any taxable year (but in no case less
than zero), determined without reference to any carrybacks or carryforwards of
any net operating loss, net capital loss, charitable contribution or other item
attributable to any other taxable period, as

                                      -3-
<PAGE>
 
determined on a basis that is consistent with the manner in which the member of
the MMD Group and DCC Group's Separate Taxable Income has been determined in the
past.  If no Combined Return has previously been filed with a Tax Authority, the
Separate Taxable Income shall be determined by DCC in a reasonable manner in
accordance with its past practice of computing Separate Taxable Income in Non-
Federal Tax Returns filed with other Tax Authorities.

          m. "Tax Authority" includes any federal, state, local, foreign or
other governmental authority responsible for the administration of any Taxes
(domestic, foreign, or possessions).

          n. "Tax Returns" shall mean Non-Federal Tax Returns and all federal
tax returns (including federal income tax returns);

          o. "Taxes" shall mean Non-Federal Taxes and all federal taxes
(including federal income taxes).

     Section 2.  Preparation and Filing of Non-Federal Tax Returns.

          2.1.  Non-Federal Tax Returns.  With respect to any Combined Return
filed after the Effective Date, DCC shall prepare, or cause to be prepared, such
Combined Return consistent with past practice.  MMD shall provide to DCC all
finalized and complete information necessary for DCC to prepare the Combined
Return (including, but not limited to, a pro forma federal income tax return) no
later than 26 days prior to the Extended Due Date of such Combined Return.  With
respect to each such Combined Return, DCC shall prepare a finalized and complete
pro forma Combined Return that is reasonably acceptable to MMD and suitable for
filing with the appropriate Tax Authority.  DCC shall submit each pro forma
Combined Return to MMD, for MMD's review and approval (which approval shall not
be withheld so long as the Combined Return is prepared in accordance with past
practice), no later than two weeks prior to the Extended Due Date.  MMD shall
review such pro forma Combined Return within one week of receipt of such
Combined Return.  Upon filing a Combined Return with the appropriate Tax
Authority, DCC shall provide MMD with a copy of the Combined Return that has
been filed with the appropriate Tax Authority.  DCC shall not file any Combined
Return with respect to the Non-Federal Taxes of any jurisdiction for which DCC
would not have filed a Combined Return under its past practice unless required
to do so by the appropriate Tax Authority.

          2.2.  Consistent Preparation of Combined Returns.  The Combined
Returns described in this Section 2, shall be prepared on a basis that is
consistent with the manner in which such Combined Returns were prepared and
filed prior to the date hereof, unless a contrary treatment is required by law
or final

                                      -4-
<PAGE>
 
or temporary regulation or MMD and DCC otherwise agree.  If no Combined Return
has previously been filed with a Tax Authority, DCC shall prepare, or cause to
be prepared, the Combined Return in accordance with its past practice of
preparing, or causing to be prepared, Combined Returns with other Tax
Authorities.

          2.3  Combined Returns for Periods that Include the Effective Date.
With respect to any Combined Returns that include periods after the Effective
Date, DCC shall file a Combined Return with the appropriate Tax Authority
reflecting income, gain, loss, deductions or credits of each included member of
the MMD Group and the DCC Group for the period up to and including the Effective
Date based on a closing of the member of the MMD Group's books on the Effective
Date.  Each of the members of the MMD Group shall prepare and provide to DCC a
closing of the books computation.  However, if either (i) a specified method is
mandated by the Tax Authority or (ii) the Tax Authority refuses to accept a
Combined Return prepared on such a basis and requires DCC to include income,
gain, loss, deductions or credits of any member of the MMD Group in the Combined
Return on a different basis, such Combined Return or any amended Combined Return
shall be prepared in accordance with such rules.

     Section 3.  Payment of Taxes.

          3.1.  Non-Federal Taxes for Combined Returns.  Consistent with past
practice, DCC shall pay, or cause to be paid, to the appropriate Tax Authorities
all Combined Taxes, if any, due and payable for all Combined Reports.  Members
of the MMD Group shall pay any refunds received from a Tax Authority with
respect to a Combined Report within 30 days of receipt of such refund; provided,
however that the payment of a refund shall not reduce, or offset any obligation
that DCC may have under Section 4.2 hereof.

          3.2.  True-up; Combined Taxes.  Within 90 days after the earlier of
(i) filing any Combined Report or (ii) paying any Combined Tax, DCC shall
prepare, or cause to be prepared, and submit to each member of the MMD Group a
true-up calculation, as determined on a basis that is consistent with the manner
in which such calculations have been determined in the past that computes the
MMD Member Liability calculated pursuant to Section 1(h) of this Agreement for
such period.  Each member of the MMD Group shall promptly review such
calculation, and, unless such member has any reasonable objections, shall make a
cash payment to DCC equal to the MMD Member Liability within 20 days of the
receipt of the true-up calculation.

                                      -5-
<PAGE>
 
     Section 4.  Redetermination.

          4.1.    Definition of Redetermination. In the event of any (i)
determination by a Tax Authority that any member of the DCC Group is required to
file a Combined Return with any member of the MMD Group for a taxable period
(where DCC and such member of the MMD Group did not file a Combined Return with
such Tax Authority for such taxable period) or (ii) redetermination of (a) any
Tax item of income, gain, loss, deduction, or credit or any other item affecting
the Tax liability of MMD or DCC for any Combined Return of any member of the MMD
Group or the DCC Group that is includable in a Combined Return or (b) the
question whether a member of the MMD Group or DCC Group has nexus to a
particular state, all as a result of a final assessment, settlement, or
compromise with any Tax Authority (including any federal adjustment) or a
judicial decision that has become final (collectively, a "Redetermination"), (i)
DCC shall recompute (a) the Combined Taxes, (b) the Separate Taxable Income of
each member of the MMD Group or DCC Group, and (c) the MMD Member Liability to
take into account such Redetermination (ii) DCC shall provide such computations
to MMD for MMD's review and approval (which approval shall not be unreasonably
withheld) (iii) MMD shall review such computations within five days of receipt
of such computations, and (iv) upon obtaining MMD's approval, DCC shall file, to
the extent permitted or required by law, an amended Combined Return with the
appropriate Tax Authority.  Upon filing an amended Combined Return with the
appropriate Tax Authority, DCC shall provide MMD with a copy of the original
Combined Return (unless previously provided) and the amended Combined Return
that has been filed with the appropriate Tax Authority.

          4.2.  Redetermination of Non-Federal Taxes.  If a Redetermination
results in an increase or decrease in the MMD Member Liability calculated
pursuant to Section 1(h) of this Agreement, each member of the MMD Group shall
pay to DCC any increase in the MMD Member Liability for such year within ninety
days of DCC's payment of any additional Combined Tax to the appropriate Tax
Authority and DCC shall pay to each member of the MMD Group any decrease in the
MMD Member Liability for such year within ninety days of DCC's receipt of a
refund from the appropriate Tax Authority.  If there is no increase or decrease
in Combined Taxes as a result of the Redetermination or DCC otherwise makes no
payment or receives no refund from the appropriate Tax Authority, MMD or DCC
shall make any payment due pursuant to Section 4.1 to their respective
counterpart within ninety days of the Redetermination.

                                      -6-
<PAGE>
 
     Section 5.   Audits, Disputes, Etc

          5.1.    Non-Federal Taxes.  DCC shall have the sole authority to
defend and contest a claim made by a Tax Authority on Audit or by appropriate
claim for refund or credit of Combined Taxes with respect to any Combined
Returns; provided, however, that DCC shall (i) act in good faith with respect to
the MMD Group in defending and settling a claim, (ii) not act in a manner that
at the same time would benefit DCC (or any of its affiliates) and adversely
affect the MMD Group, and (iii) not settle any Non-Federal Tax matter for which
MMD may have liability under this Agreement ("MMD Matter") without the prior
written consent of MMD, which consent shall not be unreasonably withheld.  In
the event MMD wants to contest a MMD Matter, MMD may request DCC's written
consent, which consent shall not be unreasonably withheld, that MMD be entitled
to contest, resolve and defend against any MMD Matter, at MMD's expense;
provided, however, that DCC shall not be obligated to provide such requested
consent, if DCC determines that (i) MMD may assert a position with respect to
such MMD Matter that is contrary to or undermines a position that has been or
may be asserted by DCC with respect to a similar Non-Federal Tax matter or (ii)
provision of such consent would unreasonably delay or hinder DCC's resolution of
any Audit or other Non-Federal Tax matter.  DCC shall have the exclusive right
to file any amended Combined Return or sign a closing agreement; provided,
however, that DCC shall not file any such amended Combined Return or sign a
closing agreement that contains a MMD Matter without the prior written consent
of MMD, which consent shall not be unreasonably withheld.  However, nothing
herein shall (i) entitle MMD to interfere with DCC's right to take any actions
it deems appropriate in connection with the disposition of any proposed
adjustments on Tax Returns filed by DCC (other than Combined Returns, but
including, but not limited to, federal Tax Returns) or (ii) entitle DCC to
interfere with MMD's right to take any actions it deems appropriate in
connection with the disposition of any Tax Returns filed by MMD (including, but
not limited to, federal Tax Returns).

          5.2.  Notification.  The parties shall forward to their respective
counterpart any notice of any pending or threatened Audit (including any federal
audit) or other proceeding within 20 days of the party's receipt of such notice
that may affect such counterpart's liability for Taxes.  The parties shall
promptly notify their respective counterpart of any proposed adjustment of any
item on any Tax Return within 20 days of receipt of notice of the proposed
adjustment if such proposed adjustment may affect the Tax liability of the
counterpart.  The parties shall advise the other party of the status of any
conferences, meetings and proceedings with Tax Authorities or appearances before
any court pertaining to such adjustment or adjustments on any Combined

                                      -7-
<PAGE>
 
Return or any other Tax Return that may affect the Tax liability of the other
party and shall advise the other party of the outcome of such proceedings.

     Section 6.  Mutual Cooperation.  DCC and MMD (or any subsidiaries or
successors of such entities) shall cooperate with each other in the filing of
any Tax Return, amendment thereto, or consent contemplated by this Agreement and
to take such action as such other party may reasonably request, including (but
not limited to):

          a. providing data for the preparation of any original or amended Tax
Returns;

          b. cooperating fully with each other in connection with (i) the
preparation and filing of any Combined Returns, (ii) the computation of the MMD
Member Liability (including adjustments to the MMD Member Liability as a result
of Redetermination), and (iii) the exchange of information relating to the
operations and business of the MMD Group or the DCC Group which is relevant to
the MMD Group or the DCC Group in preparing any Tax Returns required to be filed
by DCC or MMD (or any of their respective affiliates), including, but not
limited to, information relating to (a) intercompany loans between the MMD's
subsidiaries and DCC or its subsidiaries that trigger United States federal
income tax under the Internal Revenue Code, and require DCC to provide detailed
information on the sourcing of interest payment by MMD subsidiaries and (b) the
calculations of the research and development credit for MMD which is currently
calculated as part of the DCC credit.  Such cooperation shall include, without
limitation, the furnishing of or making available of records, books of account
or other materials and access to personnel of MMD and DCC (and their affiliates)
necessary or helpful for the preparation of Tax Returns or the defense against
assertions of any Tax Authority (including any federal tax authority) as to any
Tax Returns, so long as such access does not unreasonably interfere with the
business activities of such personnel.  The requesting party shall pay any out-
of-pocket expenses incurred by the other party but will not compensate the other
party for other expenses, including time spent by employees of the other party
assisting the requesting party;

          c. cooperating in any Audit (including any federal audit), including
the execution of limited powers of attorney that do not permit the entry into of
any settlement agreement, unless otherwise mutually agreed to by the parties;

          d. filing protests or otherwise contesting any Audit (including any
federal audit), including the filing of petitions for redetermination or
prosecuting actions for refund in any court and pursuing the appeal of any such
actions;

                                      -8-
<PAGE>
 
          e.  retaining and providing on demand books, records, documentation or
other information relating to any Tax Return until the expiration of the
applicable statute of limitation (giving effect to any extension, waiver, or
mitigation thereof), providing additional information and explanation of
material provided hereunder, and the use of the parties' commercially reasonable
efforts to obtain any documentation from a governmental authority or third party
that may be necessary or helpful in connection with the foregoing.

     Section 7.  Resolution of Certain Conflicts.  In the event that DCC and MMD
cannot agree on the calculation of any MMD Member Liability, Separate Taxable
Income, or other amount covered by this Agreement, DCC and MMD will engage an
independent, certified public accounting firm of national reputation, reasonably
acceptable to each party, to make such calculation and the decision of such firm
will be conclusive.  Such calculation shall be made in accordance with the terms
of this Agreement and past practice between DCC and MMD.  The cost of such
engagement will be borne solely by the party that does not prevail in
substantial part in the determination of the firm that is engaged; provided,
however, that if such firm determines that neither party prevailed in
substantial part, the cost of such engagement shall be shared equally by DCC and
MMD.

     Section 8.  Tax Returns for Periods Beginning on or After the Effective
Date.  Except as where required by law, DCC shall not prepare any Combined
Returns or file any Combined Returns with a Tax Authority for Tax periods
beginning on or after the day after the Effective Date.

     Section  9.  Other Taxes.  To the extent DCC pays any Taxes (including, but
not limited to payroll taxes, but other than Taxes specifically covered by
another section of this Agreement) on behalf of the MMD Group for any period up
to and including the Effective Time, DCC will continue to rebill the MMD Group
for any Taxes paid on behalf of such members and such members of the MMD Group
agree to make payments to DCC of such amounts within twenty days of the receipt
of such bill and supporting documentation including a written explanation
reasonably satisfactory to MMD.

     Section 10.  Statute of Limitations.  MMD, and each member of the MMD
Group, agrees to extend the statute of limitations on any Combined Returns to
the extent requested by DCC.

     Section 11.  Miscellaneous.

          a. Effectiveness.  This Agreement will be effective as of the
Effective Date.

                                      -9-
<PAGE>
 
          b.  Entire Agreement.  Except as provided in the Merger Agreement,
this Agreement contains the entire agreement among the parties hereto with
respect to the subject matter hereof and supersedes all prior agreements with
respect to such subject matter.

          c. Severability.  In case any one or more of the provisions contained
in this Agreement should be invalid, illegal or unenforceable, the
enforceability of the remaining provisions hereof will not in any way be
effected or impaired thereby.

          d. Time of Payment.  Any payment required to be made under this
Agreement for which the terms of payment are not specifically provided elsewhere
in this Agreement shall be paid within 90 days following the date on which the
amount of the underlying liability to which such payment relates is paid.  Any
amount required to be paid under this Agreement, which is not paid by the end of
such 90-day period, will thereafter bear interest at the 90-day London Interbank
Offered Rate plus 50 basis points from the date of such payment to the
appropriate Tax Authority to the date of full payment to the appropriate party
hereunder.

          e. Governing Law.  This Agreement shall be governed by and construed
in accordance with the law of the State of Delaware, without regard to the
principles of conflicts of law thereof.

          f. Notices.  All notices, requests, claims, demands and other
communications hereunder shall be in writing and shall be given (and shall be
deemed to have been duly given upon receipt) by delivery in person, by facsimile
or by registered or certified mail (postage prepaid, return receipt requested),
to the other party as follows:

          if to MMD or a member of the MMD Group:

           Marion Merrell Dow Inc.
           9300 Ward Parkway
           Kansas City, Missouri 64114
           Fax: (816) 966-3235
           Attention: Kevin M. Hartley (Tax Department)

                                      -10-
<PAGE>
 
          with a copy to:

           Hoechst Celanese Corporation
           Route 202-206
           P.O. Box 2500
           Somerville, New Jersey 08876-1258
           Fax:  908-231-4811
           Attention:  John M. Kacani
                    Vice-President Taxes

          and a copy to:

           Skadden, Arps, Slate, Meagher & Flom
           1440 New York Ave., N.W.
           Washington, D.C. 20005
           Fax:  202-393-5760
           Attention:  J. Phillip Adams
                         and
                       Clifford R. Gross

          and a copy to:

           Shook, Hardy & Bacon PC
           One Kansas City Street
           1200 Main Place
           Kansas City, Missouri 64105-2118
           Fax: 816-421-5547
           Attention:  Richard D. Martinson

          if to DCC, to:

           The Dow Chemical Company
           2030 Dow Center
           Midland, Michigan 48674
           Fax: 517-636-5850
           Attention: Dorra Bost (Tax Department)

          with a copy to:

           Mayer, Brown & Platt
           190 South LaSalle Street
           Chicago, Illinois 60603-3491
           Fax: 312-707-7711
           Attention:  Scott J. Davis
                         and
                       Timothy C. Sherck

or to such other address as the person to whom notice is given may have
previously furnished to the other in writing in the manner set forth above.

                                     -11-
<PAGE>
 
          g.  Modification or Amendment.  This Agreement may not be modified or
amended without the prior written consent of DCC, Hoechst, and MMD.

          h. Successors and Assigns.  A party's rights and obligations under
this Agreement may not be assigned or delegated without the prior written
consent of the other party.  All of the provisions of this Agreement will be
binding upon and inure to the benefit of the parties and their respective
successors and permitted assigns.

          i. No Third-Party Beneficiaries.  This Agreement is solely for the
benefit of the parties to this Agreement and should not be deemed to confer upon
third parties any remedy, claim, liability, reimbursement, claim of action or
other right in excess of those existing without this Agreement.

          j. MMD Payments.  To the extent that any member of the MMD Group fails
to make any payments due to DCC provided under the terms of this Agreement on a
timely basis, MMD shall become liable for such payments and will make such
payments pursuant to the terms of this Agreement.

          k. Hoechst Payments.  To the extent that MMD fails to make any
payments due to DCC provided under the terms of this Agreement on a timely
basis, Hoechst   shall become liable for such payments and will make such
payments pursuant to the terms of this Agreement.

                                     -12-

<PAGE>
 
     IN WITNESS WHEREOF, the parties hereto have duly executed this Agreement as
of the date first written above.


                                The Dow Chemical Company


                                By: 
                                    ---------------------------------------

                                Title: 
                                       ------------------------------------

                                Date: 
                                      -------------------------------------


                                Marion Merrell Dow Inc.


                                By: Fred W. Lynes Jr.
                                    ---------------------------------------

                                Title: Chairman and Chief Executive Officer
                                       ------------------------------------

                                Date: 
                                      -------------------------------------


                                Hoechst Corporation


                                By: 
                                    ---------------------------------------

                                Title: 
                                       ------------------------------------

                                Date: 
                                      -------------------------------------


 
     IN WITNESS WHEREOF, the parties hereto have duly executed this Agreement as
of the date first written above.


                                The Dow Chemical Company


                                By: Charlie J. Helen
                                    ---------------------------------------

                                Title: Tax Director and Asst. Secretary
                                       ------------------------------------

                                Date: May 3, 1995
                                      -------------------------------------


                                Marion Merrell Dow Inc.

                                By: Charles D. Delta
                                    ---------------------------------------

                                Title: Vice President
                                       ------------------------------------

                                Date: May 3, 1995
                                      -------------------------------------


                                Hoechst Corporation

                                By: 
                                    ---------------------------------------

                                Title:
                                      -------------------------------------

                                Date:
                                      -------------------------------------

<PAGE>
 
     IN WITNESS WHEREOF, the parties hereto have duly executed this Agreement as
of the date first written above.


                                The Dow Chemical Company


                                By: 
                                    ---------------------------------------

                                Title: 
                                       ------------------------------------

                                Date: 
                                      -------------------------------------

                                Marion Merrell Dow Inc.


                                By: 
                                    ---------------------------------------

                                Title: 
                                       ------------------------------------

                                Date: 
                                      -------------------------------------

                                Hoechst Corporation


                                By: Harry Benz
                                    ---------------------------------------

                                Title: Secretary and Treasurer
                                       ------------------------------------

                                Date: May 3, 1995
                                      -------------------------------------


<PAGE>
 



SCHEDULE 1(h) TO THE TAX ALLOCATION AGREEMENT
UNITARY STATES


<TABLE> 
<CAPTION> 
                                                         DOMESTIC SUBS                                   FOREIGN OR POSSESSIONS SUBS
                           --------------------------------------------------------------------------    ---------------------------
                                                                     MARION                                               MARION'S 
                           MARION        MERRELL                     MERRELL                ALL OTHER    RC SEG. 838     CONTROLLED
                           MERRELL         DOW           RUGBY       CONSUMER     MARISUB   DOMESTIC      MARION &         FOREIGN 
      STATE:               DOW INC   PHARMACEUTICALS   GROUP INC   PRODUCTS INC      V        SUBS         COMPANY      CORPORATIONS
- -----------------          -------   ---------------   ---------   ------------   -------   ---------    -----------    ------------
<S>                        <C>       <C>               <C>         <C>            <C>       <C>          <C>            <C>
(1) ARIZONA                   X                                         X       
(2) CALIFORNIA                X                            X            X       
(3) MAINE                     X                                         X                          
(4) MONTANA                   X                            X            X                         
(5) NEW HAMPSHIRE             X                                         X                          
(6) UTAH                      X                                         X                           
</TABLE> 



X - DENOTES A NEXUS PRESENCE AS HISTORICALLY DEFINED AND INTERPRETED BY NMD AND 
DCC.

THE ABSENCE OF AN X MEANS: THERE IS NO NEXUS PRESENCE AS HISTORICALLY DEFINED 
AND INTERPRETED BY NMD AND DCC.

<PAGE>
 
                COMPUTERIZED PROCESS CONTROL SOFTWARE AGREEMENT

                             (LEASES AND SERVICES)

     This lease and service agreement, hereinafter "Agreement," is made and
entered into effective May 3, 1995, by and between ROFAN SERVICES INC.
(hereinafter "Lessor") and MERRELL DOW PHARMACEUTICALS INC. (hereinafter
"Lessee"), located at:

     LESSOR:            ROFAN SERVICES INC.

     Address:           2030 Willard H. Dow Center
                        Midland, MI  48674

     Corporation of:    State of Delaware

     Authorized leasing representative for MOD5 SYSTEMS.

     LESSEE:            MERRELL DOW PHARMACEUTICALS INC.

     Address:           2110 E. Galbraith Road
                        Cincinnati, OH  45215

     Corporation of:    State of Delaware

     Lessor and Lessee hereby agree this Agreement consists in its entirety of
this executed covering document and the following attachments:

     APPENDIX A - SERVICE AGREEMENT

     APPENDIX B - MOD5 SPECIAL SERVICE ADDENDUM

     SCHEDULE 1 - LEASED MOD5 SOFTWARE

     Lessor agrees to lease to Lessee and Lessee agrees to lease from Lessor in
accordance with the terms and conditions of this Agreement MOD5 SOFTWARE as
delineated in Schedule 1 to integrally generate, transmit and manage process
control at the PLANTS listed in Schedule 1 attached hereto and made a part
hereof. This Agreement constitutes the entire understanding between Lessee and
Lessor pertaining to all MOD5 SOFTWARE for

                                      -1-
<PAGE>
 
Lessee's PLANTS and supersedes any prior or contemporaneous agreements and all
negotiations, representations and proposals written or oral pertaining to this
subject.

1.   Definitions
     -----------
     Terms used in this Agreement shall have the meanings ascribed to them as
follows:

1.1  Software Definitions
     --------------------
     (a) MOD5 SOFTWARE means (1) MOD5 CAN SOFTWARE, (2) SERIEAL GRAPHICS
SOFTWARE, and (3) GPI based on specially designed, direct digital control,
redundant computer technology to provide process control and process operation
information for execution on MOD5 HARDWARE.

     (b) MOD5 SYSTEM is a specific implementation of MOD5 HARDWARE and MOD5
SOFTWARE in a PLANT.  Within a given PLANT there may be one or more MOD5
SYSTEMS.

     (c) MOD5 CAN SOFTWARE means MOD5 OVERHEADS including associated FIRMWARE,
DOWTRAN SUPPORT TOOLS, and MOD5 COMPILER.

     (d) FIRMWARE is a physical means containing electronically retrievable
information pertaining to MOD5 SOFTWARE.

     (e) INTERFACE PROCESSOR is a functional interconnection within a system
between the MOD5 OVERHEADS and other MOD5 SOFTWARE, which contains hardware,
dedicated executable software, and FIRMWARE.

     (f) DOWTRAN is a specific language designed for the process control
application engineer to convert and express the CONTROL SCHEMA into an
APPLICATION PROGRAM for a manufacturing 

                                      -2-
<PAGE>
 
process. The APPLICATION PROGRAM is further transformed into COMPILED DOWTRAN
using a MOD5 COMPILER.

     (g) MOD5 OVERHEADS means the redundantly deployed, executable operating
system software and, optionally, protocol use rights, for the MOD5 COMPUTER that
executes the COMPILED DOWTRAN and implements diagnostics, inputs, outputs,
alarms and event logging.

     (h) DOWTRAN SUPPORT TOOLS are utility programs which execute on the
MINICOMPUTER to assist the application engineer in writing the APPLICATION
PROGRAM in DOWTRAN.

     (i) APPLICATION PROGRAM is the set of sequential human readable
representations of the evolving CONTROL SCHEMA in DOWTRAN, where the set is
designated with an essentially consistent logical identifier.

     (j) COMPILED DOWTRAN is the set of respective sequential instances of
machine readable code, redundantly deployed, which results from the compilation
process executed by the MOD5 COMPILER to convert the APPLICATION PROGRAM written
in DOWTRAN into said machine readable code.

     (k) CONTROL SCHEMA comprises the entire collection of concepts, process
dynamics and control models, and associated decision models which are referenced
to define the APPLICATION PROGRAM.

     (l) MOD5 COMPILER is a computer program which executes on the MINICOMPUTER
to produce COMPILED DOWTRAN from the APPLICATION PROGRAM written in the DOWTRAN
language.

     (m) GPI means an executable subset of process information and related
software specially designed and developed for execution on the MINICOMPUTER
which displays and stores process 

                                      -3-
<PAGE>
 
information and related information to assist operations personnel.

     (n) SERIAL GRAPHICS SOFTWARE means Lessor supplied software, associated
FIRMWARE, and protocol use rights to implement SERIAL GRAPHICS.

1.2  Associated Hardware Definitions
     -------------------------------
     (a) MOD5 HARDWARE means a user defined hardware configuration designed to
implement the MOD5 CAN SOFTWARE which comprises two or more MOD CANS, two or
more MOD5 COMPUTERS, and one or more INTERFACE PROCESSORS.  MOD5 HARDWARE
further comprises the Lessor specified hardware (excluding FIRMWARE) resident
within the MOD5 COMPUTER which is used in the linking of the MOD5 COMPUTER to at
least one INTERFACE PROCESSOR.

     (b) MOD CAN is a modular input/output device with associated electronics
which receives inputs and originates output relative to PLANT instrumentation.

     (c) MOD5 COMPUTER is a Lessor specified, high speed control computer.

     (d) MINICOMPUTER is a member of a family of computers manufactured by the
Digital Equipment Corporation comprising VAX (or, optionally, AXP) hardware
executing the currently supported version of the VMS (or, optionally, Open VMS)
operating system specified by Lessor, said computers otherwise referred to as
VAX/VMS (or, optionally, AXP/Open VMS) systems, to be separately acquired by
Lessee.

     (e) SERIAL GRAPHICS is a programmable display panel means which executes
SERIAL GRAPHICS SOFTWARE for consistent holistic display of immediate (REAL-
TIME) information, within the context of a fixed pictorial background, depicting
the status of a set 

                                      -4-
<PAGE>
 
of PROCESS CONTROL SIGNALS in the domain of a particular APPLICATION PROGRAM as
its derived COMPILED DOWTRAN executes on its affiliated redundant MOD5 COMPUTER
system. The SERIAL GRAPHICS programmable display panel system communicates with
its affiliated redundant MOD5 COMPUTER system using a network protocol.

1.3  Miscellaneous Definitions
     -------------------------
     (a) PROCESS CONTROL SIGNALS is the set of analog inputs, analog outputs,
digital inputs, digital outputs and the individual instances of process
variables contained within serial data messages transmitted to/from the MOD5
OVERHEADS utilized to implement an APPLICATION PROGRAM at a given PLANT.

     (b) HARDWARE CONSUMABLES include, without limitation, fuses, light bulbs,
chart paper and other such utility sundry items.

     (c) REMEDIAL PRODUCT NOTICE is a change in hardware design and/or software
design and/or announcements of procedures as may be desirable for continuing
effectiveness.

     (d) REAL-TIME is generically defined as a method of executing the MOD5
OVERHEADS in a MOD5 COMPUTER in which an event causes a given reaction within an
actual time limit and wherein MOD5 COMPUTER actions are specifically controlled
within the context of and by external conditions and actual times.

     (e) PLANT means Lessee's facilities referred to in the attached Schedule 1.
MOD5 SYSTEMS for each PLANT are specified by the number of CANS, and the
installed version of computer processing unit(s), MOD5 OVERHEADS, GPI and
DOWTRAN respectively.

     (f) EFFECTIVE DATE is the date first set forth above.

                                      -5-
<PAGE>
 
2.   Term
     ----

     The Term of this Agreement shall begin on the EFFECTIVE DATE hereof and,
subject to the provisions herein for termination, shall continue for a period of
five (5) years.  Lessee may extend this Term for an additional six (6) months on
ninety (90) days advance notice.  Lessee may terminate this lease as to any MOD5
SYSTEM at any time during the Term of this agreement on ninety (90) days advance
written notice to Lessor.  The obligations of Article 6 shall survive any
expiration or accelerated termination of this Agreement for a period of ten (10)
years from the EFFECTIVE DATE.

3.   Payments
     --------

     3.1  Lease Charges  Lease charges for MOD5 SOFTWARE leased hereunder are
set forth in the accompanying Schedule 1.  These charges shall be invoiced
within thirty (30) days of the EFFECTIVE DATE and upon each yearly anniversary
thereof during the term of this Agreement and shall be payable within thirty
(30) days of receipt of an invoice therefor.

     3.2  Taxes  Lessee shall pay all taxes, however designated, which are
levied or based on the lease including, without limitation, property taxes,
local fees or excise taxes, but excluding taxes thereon based on income to
Lessor.  In the event Lessee defaults in the payment of any such tax, Lessor may
pay such tax and shall be reimbursed by Lessee, with interest, as additional
lease charges.

4.   Terms of Possession and Use
     ---------------------------

     4.1  Lessor and Lessee agree that all MOD5 SOFTWARE leased by Lessor
hereunder will be kept by Lessee in its sole possession and control and will at
all times be located at the PLANTS designated in the attached Schedule 1.  The
parties will 

                                      -6-
<PAGE>
 
mutually cooperate to keep Schedule 1 current as to installed MOD5 SYSTEMS at
each PLANT.

     4.2  Lessee shall enjoy all rights of possession and use of MOD5 SOFTWARE
leased hereunder subject to Lessor's rights under Paragraph 4.3. upon the
occurrence of one or more of the following conditions:

          (a) Lessee breaches the secrecy obligations of Article 6;

          (b) Lessee fails to make payments within sixty (60) days after notice
     of payments in arrears;
     
          (c) Lessee ceases to own or control facilities in which MOD5 SYSTEMS
     are installed, unless Lessee's transfer of ownership or control occurs
     pursuant to Article 14;

          (d) Lessee ceases to use MOD5 SYSTEMS, or uses them for a purpose
     other than their original installation, or modifies them by integrally
     combining internal MOD5 SYSTEM physical or logical components with systems
     of others with the proviso that when switching from a MOD5 SYSTEM to a
     different process control system at a given PLANT the MOD5 SYSTEM may be
     operated (as far as reasonably possible in decoupled status) in parallel
     with the other system;

          (e) Lessor is prevented by a Force Majeure condition from supporting
     MOD5 SOFTWARE acquired by Lessee hereunder.

          (f) Lessee terminates this Agreement totally or in part as to any MOD5
     SYSTEM.

                                      -7-
<PAGE>
 
     4.3  In the event one or more conditions of Paragraphs 4.2(a), (b), (c),
(d), or (e) occurs, Lessor may terminate this Agreement and its support of MOD5
SYSTEMS and MOD5 SOFTWARE shall be returned to Lessor.  In the event Lessee
exercises rights of unilateral termination under Paragraph 4.2(f), Lessor will
terminate its support of such MOD5 SYSTEM and MOD5 SOFTWARE associated with such
SYSTEM shall be returned to Lessor, subject to Lessee rights specified in
Article 5. Lessee will permit reasonable access of Lessor to the PLANTS to
assist in the removal and return of MOD5 SOFTWARE.

5.   Lessor Property
     ---------------

     5.1  Lessor and Lessee agree that all MOD5 SOFTWARE leased hereunder
remains the personal property of Lessor or Lessor's grantor and, subject to
Lessee's reasonable operating, safety and secrecy requirements.  Lessee shall
permit access of Lessor or Lessor's designee to the PLANTS at any time after
termination of this Agreement to permit removal of the same.  Lessee will keep
and maintain the MOD5 SOFTWARE free and clear of all liens, charges and
encumbrances.

     5.2  The glossaried and commented DOWTRAN language listing of the
APPLICATION PROGRAM produced by Lessee shall be considered derivative software
and, as such, it is owned by Lessee with the proviso that Lessee will diligently
pursue protecting Lessor's interests pursuant to Article 6.  To facilitate
Lessee's understanding of the retained derivative APPLICATION PROGRAM, Lessee
may also retain the accompanying DOWTRAN application training manuals and any
cross references to sub-routine listings in the APPLICATION PROGRAM.  Upon
expiration of this lease these written materials retained by Lessee shall be
considered proprietary information of Lessor licensed to Lessee subject to the
terms of Article 6.  The 

                                      -8-
<PAGE>
 
compiled DOWTRAN listing from the MOD5 COMPILER is property of and shall be
returned to Lessor along with MOD5 SOFTWARE.

6.   Confidentiality
     ---------------

     MOD5 SYSTEMS comprise unique, valuable, proprietary information.  Lessee
agrees to maintain and protect Lessor's interests in proprietary information and
will accordingly keep all information pertaining to MOD5 SYSTEMS in confidence
and not use the same except as is necessary to the enjoyment and exercise of the
leases granted by Lessor hereunder at the PLANTS listed in the attached Schedule
1.  Lessee will take diligent action to fulfill the foregoing obligations by
instruction and agreement with its employees or agents respecting the
confidentiality of this information and shall obtain from them their written
commitments to comply with terms of confidentiality.

7.   Software Copies
     ---------------

     MOD5 SOFTWARE may only be copied, in whole or part, with proper inclusion
of Lessor's copyright notice and any other proprietary notice required by
Lessor, as necessary and incidental to the use of such software for archival and
backup purposes or to replace a worn or defective copy.  All such copies shall
be subject to the terms and conditions of this Agreement and shall be kept and
used at the designated PLANTS.  If Lessee is unable to operate the MOD5 SOFTWARE
on originally installed equipment, the MOD5 SOFTWARE may be transferred
temporarily to another system during the period of equipment malfunction.

8.   Warranties, Disclaimers and Validations
     ---------------------------------------

     8.1  THE EXPRESSED WARRANTIES HEREIN CONTAINED ARE IN LIEU OF ANY AND ALL
OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 

                                      -9-
<PAGE>
 
THE WARRANTY OF MERCHANTABILITY AND OF FITNESS FOR A PARTICULAR PURPOSE. Lessor
warrants that MOD5 SOFTWARE as delivered will operate substantially as indicated
in documentation provided by Lessor and will replace or provide instructions to
adjust malfunctioning components of MOD5 SOFTWARE on receiving notice thereof
from Lessee. Lessor will expeditiously address the notice with, alternatively at
Lessor's discretion, replacement of the component with a currently available
MOD5 SOFTWARE component or instructions for corrective logical modification of,
or other accommodative procedure for, the MOD5 SOFTWARE addressing the
malfunction. Lessee shall promptly, upon discovery, notify Lessor of any alleged
deficiency which may exist.

     8.2  Lessor warrants that the MOD5 SOFTWARE as delivered by Lessor under
this Agreement shall not infringe copyrights or patent rights of a third party
existing on the EFFECTIVE DATE.  Upon prompt written notice from Lessee
providing all pertinent details of a claim of such asserted infringement, Lessor
will undertake to investigate and at Lessor's expense to settle or to defend
against such a claim, provided Lessee grants any necessary authority and gives
its full support and cooperation, or to obtain the right for Lessee to continue
to use the MOD5 SOFTWARE, or to replace or modify the allegedly infringing
components of the MOD5 SOFTWARE which Lessor has so delivered to avoid any such
claim that is found to be valid.  Without prejudice to the generality of the
foregoing, such expense shall extend to reasonable attorneys' fees incurred by
Lessee in respect of such claim.  If an award is rendered against Lessee, in any
litigation that the Lessor defends hereunder for infringement by the components
of the MOD5 SOFTWARE which Lessor has so delivered, then Lessor shall reimburse
Lessee for damages and costs awarded by the judicial authority in respect to
those components.

                                      -10-
<PAGE>
 
     8.3  Lessee acknowledges that it is responsible for each APPLICATION
PROGRAM and is not relying on Lessor's skill or judgment to select or furnish
MOD5 SOFTWARE and associated MOD5 HARDWARE suitable for operation of a
particular manufacturing process and that there are no warranties which are not
contained in this Agreement.  Lessee acknowledges that it has made the selection
of the associated MOD5 HARDWARE.  Lessor shall not be liable for special,
incidental or consequential damages arising out of or in connection with the
performance of systems utilizing MOD5 SOFTWARE and associated MOD5 HARDWARE.
Lessor shall not be responsible for any loss or damage caused by, nor shall any
payments due hereunder abate by reason of, any interruption in or loss of
service or use of the equipment or any part thereof arising from any reason not
solely attributable to Lessor.  Without limiting the generality of the
foregoing, examples of the foregoing include errors in the APPLICATION PROGRAM,
normal wear and tear of the MOD5 SOFTWARE, or gradual deterioration of the MOD5
SOFTWARE.

     8.4  Lessor's total obligation after the EFFECTIVE DATE under this Article
shall in no event exceed one hundred percent (100%) of the total amount of the
payments actually received by Lessor under this Agreement.

     8.5  Whenever and to the extent validation of MOD5 SYSTEMS has occurred
under FDA regulations to date, Lessee shall retain those reports in support of
validation.  If revalidation of the process control system is necessary because
of extended requirements of the FDA regulations, Lessor shall provide
information reasonably required.

     8.6  With regard to any FDA validations in progress, or those to be
conducted in the future, Lessor shall provide information reasonably required
under FDA regulations with respect to MOD5 SYSTEMS validation.

                                      -11-
<PAGE>
 
9.   Liability, Indemnity and Risk of Loss
     -------------------------------------

     Lessee assumes all risks and liabilities, whether or not covered by
insurance, and shall indemnify and hold Lessor and its employees harmless for
any liability, claim, loss, damage or expense for injuries to or deaths of
persons and for damage to property, howsoever arising from or incident to the
possession, use, operation or storage of MOD5 SOFTWARE and associated MOD5
HARDWARE, and operation of the MOD5 SYSTEM, save and except for any matter
attributable to the sole negligence or willful misconduct of Lessor.  Said
assumption of risks and liabilities by Lessee shall apply whether such injury or
death to persons be to agents or employees of Lessee or be to third persons and
whether such damage be to property of Lessee or to property of others.

10.  MOD5 SOFTWARE Maintenance and Support
     -------------------------------------

     10.1  Throughout the Term hereunder after installation of the MOD5
SOFTWARE, Lessee shall maintain site conditions to provide an acceptable
operating environment for the MOD5 SOFTWARE as referenced in documentation
provided by Lessor.  Lessee is responsible for maintenance not provided under
the Service Agreement attached hereto as Appendix A and installation of the MOD5
SOFTWARE.  Lessee will maintain the MOD5 SOFTWARE in a current and up-to-date
condition adapting the APPLICATION PROGRAM to accommodate REMEDIAL PRODUCT
NOTICES when recommended by Lessor, which will be supplied by Lessor or by
vendors approved by Lessor.  Such adaptations will normally address operating
reliability.  Lessor will counsel Lessee, as requested pursuant to the attached
Service Agreement, to accomplish the foregoing and Lessee shall permit Lessor or
Lessor's designee access to the MOD5 SOFTWARE for providing any necessary
assistance, such access to include network access if deemed appropriate.

                                      -12-
<PAGE>
 
     10.2 Lessor agrees to supply Maintenance and Support Services for MOD5
SOFTWARE, including maintenance and adjustment of associated MOD5 HARDWARE,
solely in accordance with the Service Agreement which is incorporated as
Appendix A of this Agreement. Lessor is not responsible for supply, maintenance
and adjustment of the MINICOMPUTER, and other commercially sourced computer(s)
or commercially sourced operating system(s) used in association with MOD5
SOFTWARE.

     10.3  Subject to Lessee's reasonable operating, safety and secrecy
requirements, Lessee shall grant Lessor PLANT access to the MINICOMPUTER and
other commercially sourced computer(s) used with MOD5 SOFTWARE during normal
working hours for inspection and installation of REMEDIAL PRODUCT NOTICES and
for any other reasonable purpose, such access to include network access if
deemed appropriate.  Lessee shall immediately notify Lessor of all details
concerning any malfunction arising out of the alleged or apparent improper
manufacture, functioning or operation of the MOD5 SOFTWARE.

11.  Notices
     -------

     Lessee and Lessor agree that notices required hereunder shall be deemed
received the seventh day after mailing, if mailed air postage prepaid to Lessor
or Lessee as the case may be at their respective address given below.

     If to Lessor, to:   Rofan Services, Inc.
                         2030 Willard H. Dow Center
                         Midland, MI  48674

                         Attention:  M. N. Trask, Vice President

                                      -13-
<PAGE>
 
     If to Lessee, to:   Merrell Dow Pharmaceuticals Inc.
                         2110 E. Galbraith Road
                         Cincinnati, OH  45215

                         Attention:  _________________

Either party may change such address for notice by sending to the other party a 
written notice.

12.  Severability
     ------------

     Any provision hereof prohibited by, or unlawful or unenforceable under, any
applicable law of any jurisdiction shall be ineffective as to such jurisdiction
without invalidating the remaining provisions of this Agreement. In the event a
material provision is affected, the parties shall reformulate their mutual
undertakings in such manner as to preserve, as much as possible, their original
intentions and objects of this Agreement, consistent with the laws of such
jurisdiction.

13.  Alterations
     -----------

     Except for Lessee's remedial modification of APPLICATION PROGRAM, no
alterations to MOD5 SOFTWARE shall be made without first obtaining in each
instance the prior written approval of Lessor which approval shall be
expeditiously considered and not be unreasonably withheld.

14.  Conflicts and Assignability
     ---------------------------

     This Agreement does not operate as an acceptance of any conflicting terms
or conditions and shall prevail over any conflicting provision of any subsequent
purchase order or other instrument of Lessee, it being understood that any
purchase order or the request of Lessee acted upon by Lessor shall be for 

                                      -14-
<PAGE>
 
the convenience of Lessee only but shall not operate to amend or modify in any
respect the terms hereof. This Agreement may only be altered, modified,
supplemented or deviated from by further agreement in writing executed by an
authorized representative of each Lessor and Lessee. Lessee and Lessor
acknowledge that by executing this Agreement each has reviewed the attachments
listed above and each agrees to be legally bound and dutifully perform its
obligations thereunder. Lessor reserves the right to assign this Agreement to a
parent, affiliate or sister company of Lessor, but otherwise this Agreement
shall not be assignable by either party except to a successor of the entire
PLANT, which undertakes all obligations assumed by Lessee hereunder by an
agreement executed and copied to Lessor and to whom Lessor has no reasonable
objection.

15.  Applicable Law
     --------------

     The laws of the State of Michigan shall be applied in the construction and
interpretation of this Agreement.  No law of conflicts or choice of law shall
supersede this provision except as provided in Article 6.

     IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
on their behalf by their duly authorized representatives.

LESSOR:                         LESSEE:

ROFAN SERVICES INC.             MERRELL DOW PHARMACEUTICALS INC.


By:     John C. Lillich         By:     Charles D. Dalton
    ------------------------        --------------------------
Name:   John C. Lillich         Name:   Charles D. Dalton
      ----------------------          ------------------------
Title:       President          Title:      Vice President
       ---------------------           -----------------------
Date:      May 3, 1995          Date:          5/3/95
      ----------------------          ------------------------

                                      -15-
<PAGE>
 
                                   APPENDIX A
                                   ----------

                               SERVICE AGREEMENT

                                  MAINTENANCE


1.   Services
     --------

     (i) To facilitate efficient use of MOD5 SOFTWARE, Lessor agrees to provide
and Lessee agrees to acquire MOD5 SOFTWARE Maintenance Services as provided
hereunder.  Lessee has responsibility to acquire, through separate arrangements
with Lessor or another party, reasonable MOD5 HARDWARE training and/or services
necessary to apply DOWTRAN to the CONTROL SCHEMA and to remedially modify an
APPLICATION PROGRAM.

     (ii) Maintenance Services for MOD5 SOFTWARE include the notification of and
assistance for implementation, where necessary, of REMEDIAL PRODUCT NOTICES for
MOD5 SOFTWARE and remedial maintenance consultation for MOD5 SOFTWARE, MOD5
HARDWARE, FIRMWARE and other maintenance conducted by Lessee.  Repair of
subassemblies and printed circuit boards will by done by Lessor for Lessee's
account, i.e., at Lessee's expense, working with the vendor of such components.
Acquisition and installation of HARDWARE CONSUMABLES shall be the responsibility
of Lessee.

     (iii)  Lessor shall provide backup support for MOD5 SOFTWARE and MOD5
HARDWARE after Lessee has undertaken reasonable effort to resolve any MOD5-
related problem. Telephone support shall be provided within 24 hours of
notification of the problem and on-site service shall be provided within 48
hours of any such notification.

     (iv) Lessee shall be responsible for the appointment of one or more
computer systems professionals or process control professionals fluent in the
English language having a level of 

                                      -16-
<PAGE>
 
technical qualifications and experience acceptable to Lessor, whose acceptance
will not be unreasonably withheld, as manager for the MOD5 SOFTWARE. The MOD5
SOFTWARE manager shall enter into a secrecy agreement with Lessor to protect
Lessor's technology and shall cooperate with Lessor in enabling access to the
MOD5 SOFTWARE when appropriate.

     (v) "Special Services" reasonably required by Lessee at its PLANT sites any
time during the Term and upon termination of this lease, such as, for example,
services that may be required to assist Lessee in completing FDA validations of
process control in progress or for such technical support as may be reasonably
necessary in switching from MOD5 process control to another process control
system shall be provided by Lessor on reasonable notice for a period up to
twelve (12) workdays (8 hours per workday) over each successive twelve (12)
month period during the term of this lease measured from its EFFECTIVE DATE.
Special Service workdays not used within a given twelve (12) month period shall
not carry over to a subsequent period.

     (vi) Lessee and Lessor from time to time may agree on additional or new
Special Services beyond those agreed in this Agreement.  Any such additional or
new Special Services may be agreed to in a MOD5 Special Service Addendum. For
each separate request for services from Lessee, Lessor shall prepare and submit
to Lessee a written service proposal. The parties shall discuss the service
proposal and negotiate to agreement regarding the nature, scope, terms and
detail of the work. If agreement on the total scope is reached, the parties
shall develop a Special Service Addendum which shall define in detail the scope
of services and tasks to be performed, the schedule for completion and the
billing basis for such Special Services. Each MOD5 Special Service Addendum
shall be effective only if signed by an authorized representative of each party.
Each Special Service Addendum shall be sequentially numbered. A sample Special
Service Addendum is attached as Appendix B.

                                      -17-
<PAGE>
 
2.   Service Limitations
     -------------------

     Services are contingent upon the proper use of the MOD5 SOFTWARE and the
acquisition of associated MOD5 HARDWARE suitable for running MOD5 SOFTWARE.
Services do not include any of the following:  electrical work external to the
INTERFACE PROCESSOR, MINICOMPUTER, or other commercially sourced computer(s) or
commercially sourced operating system(s) associated with the MOD5 SYSTEM;
replacing or providing HARDWARE CONSUMABLES; refinishing MOD5 SOFTWARE; or
maintenance of accessories, attachments, machines or other devices not provided
by Lessor.  Service shall not include practices which in Lessor's judgment are
unsafe or impractical for Lessor to render because of alterations to the MOD5
SOFTWARE or connection of the PLANTS by mechanical or electrical means to
machine devices furnished by a supplier other than Lessor. Service will not be
performed on MOD5 SOFTWARE located in an unsafe or hazardous environment, as
determined by Lessor. Service to be provided does not include service
necessitated by elements external to the MOD5 SOFTWARE which are not within
Lessor's operation or maintenance instructions or installation site preparation
guidelines including, but not limited to, humidity, temperature, power failure,
surges, air conditioning, grounding, static charge control, service resulting
from accident, neglect, alterations, improper use or misuse of the MOD5 SOFTWARE
or by repairs attempted by Lessee's personnel or service to a version other than
the installed version of MOD5 SOFTWARE and MOD5 HARDWARE.

3.   Service Charges
     ---------------

     (i) For Maintenance Services described in Article 1 performed at Lessee's
PLANTS, Lessee shall pay Lessor a service charge in the amount of Lessor's
standard charge for such services, plus reasonable travel and living expenses.
This fee is presently $125.00 per hour.

                                      -18-
<PAGE>
 
     (ii) For home based maintenance and support services described in Article 1
above conducted at the home locations of Lessor and its suppliers, Lessee shall
pay Lessor an annual fee as shown on Schedule 1 determined by multiplying the
total number of MOD CANS on which MOD5 SOFTWARE is run by a standard service
fee.

     (iii)  Special Services pursuant to Article 1(v) shall be without charge
for up to 2 workdays in a single visit within each successive 12 month period
during the Term of this lease.  for additional workdays and additional visits
within each 12 month period Lessee shall pay Lessor a professional consulting
fee of $150.00 per hour for up to an additional 10 workdays.  Lessee shall
reimburse Lessor for reasonable travel and lodging expenses of such consultancy.

     (iv) Service charges accruing under this Article 3 will be invoiced and
shall be payable within thirty (30) days of receipt of an invoice therefor.

                                      -19-
<PAGE>
 
                                   APPENDIX B
                                   ----------

                     MOD5 SPECIAL SERVICE ADDENDUM NO. ___
                      (Reference Article 1(vi) Appendix A)


(A)  Scope of Special Services:



(B)  Compensation:



(C)  Term or Schedule of Completion:
<PAGE>
 
(D)  Changes to Scope of Services:



(E)  Representatives:



(F)  Responsibility for Reporting:



(G)  Termination:

     This Special Service Addendum may be terminated (i) by either party with or
     without cause at any time upon 30 days written notice, or (ii) by the non-
     breaching party upon 2 days written notice in the event the other party
     fails to cure its breach of a material obligation under the Agreement or
     this Special Service Addendum within 20 days of its receipt of a notice
     alleging such breach from the other party.
<PAGE>
 
     Upon termination of the Special Service Addendum, Lessor shall invoice
     Lessee for all services performed by Lessor under this Special Service
     Addendum prior to the termination for which Lessor was not previously
     compensated, and for expenses necessary to shut down the project.

ACCEPTED AND AGREED, as of the later of the two dates noted in the signature
blocks, by each Party's authorized representative.

Lessor:                          Lessee:

ROFAN SERVICES INC.              MERRELL DOW PHARMACEUTICALS
                                 INC.

By:_________________________     By:_________________________
Name:_______________________     Name:_______________________
Title:______________________     Title:_______________________
Date:_______________________     Date:________________________
<PAGE>
 
                                   SCHEDULE 1
                                   ----------

                              LEASED MOD5 SOFTWARE
                              --------------------
<TABLE>
<CAPTION>
                                      NUMBER OF       LEASE           ANNUAL
   SITE               PLANT           MOD CANS       CHARGES       SUPPORT FEES
   ----               -----           ---------      -------       ------------
<S>              <C>                  <C>           <C>            <C>
 
CINCINNATI,      DRY PRODUCTS             2
OHIO             LIQUID PRODUCTS          2
                 GRANEX                   2
                 NEW TECH                 2
                 SIM CAN                  1
                                          -
 
                                          9            NONE         $11,700.00
                                                    (ANTEDATES
                                                     LEASING)
</TABLE> 
 
MOD5 SYSTEMS DESCRIPTION:
- -------------------------
 
   NUMBER OF SYSTEMS:      5
 
   VERSIONS:
       CPU:                MOD5+
       OVERHEAD SOFTWARE:  6.42
       GPI:                CONVERTING TO GPI
                           (CURRENTLY USING DOWPIX)



MIDLAND,         BLDG.827                21          PAID-UP        $24,700.00
MICHIGAN                                                         (EXCLUDES MOD4)
 
 
MOD5 SYSTEMS DESCRIPTION:
- -------------------------
 
   NUMBER OF SYSTEMS:      6
 
   VERSIONS:
       CPU:                MOD4   (2 CANS)
                           MOD5 + (17 CANS)
                           MOD5E  (2 CANS)
       OVERHEAD SOFTWARE:  7.71   (15 CANS)
                           6.04   (4 CANS)
       GPI:                2.11
       DSS:                2.11
       VMS:                5.5-2
       MODSERVER SOFTWARE: 5.17

                               PAGE 1 OF 2 PAGES
<PAGE>
 
                                      NUMBER OF       LEASE           ANNUAL
  SITE            PLANT               MOD CANS       CHARGES       SUPPORT FEES
  ----            -----               ---------      -------       ------------

MIDLAND,         BLDG.1                  11          PAID-UP        $14,300.00
MICHIGAN

 
MOD5 SYSTEMS DESCRIPTION:
- -------------------------
 
   NUMBER OF SYSTEMS:      3
 
   VERSIONS:
       CPU:                MOD5E
       OVERHEAD SOFTWARE:  7.71
       GPI:                2.11
       DSS:                2.11
       VMS:                5.5-2
       MODSERVER SOFTWARE: 5.17
 



MIDLAND,          BLDG.1381         11               PAID-UP        $14,300.00
MICHIGAN

 
MOD5 SYSTEMS DESCRIPTION:
- -------------------------
 
   NUMBER OF SYSTEMS:      2
 
   VERSIONS:
       CPU:                MOD5E
       OVERHEAD SOFTWARE:  7.71
       GPI:                2.11
       DSS:                2.11
       VMS:                5.5-2h4
       MODSERVER SOFTWARE: 5.17
 


                            TOTAL ANNUAL SUPPORT FEES:              $65,000,000

                               PAGE 2 OF 2 PAGES
<PAGE>
 
                       PERSONAL CONFIDENTIALITY AGREEMENT
                       ----------------------------------


DECLARATIONS:

     The undersigned employee of Merrell Dow Pharmaceuticals Inc. (MDPI) has
certain responsibilities for maintaining and operating MOD5 SYSTEMS for
manufacturing process control.

     The undersigned Affiliate of The Dow Chemical Company (Dow) is willing to 
continue supporting MOD5 SYSTEMS used by MDPI according to the terms of the
"Computerized Process Control Software Agreement" entered into between Affiliate
and MDPI with the proviso that the latter appoint a MOD5 SOFTWARE technical
manager with appropriate competencies in the English language and pertinent
technical qualifications.

ASSURANCES:

     The undersigned acknowledges he/she has been assigned such responsibilities
regarding MOD5 SYSTEMS BY MDPI and affirms:

     1.  That he/she is familiar with the "Computerized Process Control Software
Agreement" mentioned above, including those terms thereof regarding
confidentiality of information.

     2.  That pursuant to the terms of the Agreement he/she will not disclose to
others proprietary information about MOD5 SYSTEMS nor make any unauthorized
copies of documents containing such Information, and moreover agrees that no
personal rights to use any Information acquired in working with MOD5 SYSTEMS are
expressly or impliedly acquired hereunder.

     It is understood by the undersigned and Affiliate of Dow that these
obligations shall not apply to Information which is or becomes part of the
public domain through no fault of the undersigned or is received by the
undersigned on a nonconfidential basis from a third party who is not under an
obligation of confidence to Dow or a Dow Affiliate.

ACCEPTED BY                      ROFAN SERVICES INC.
MDPI Representative:

__________________________       By:_________________________
Name:_____________________       Name:_______________________
Title:____________________       Title:______________________
Date:_____________________       Date:_______________________

<PAGE>
 
                COMPUTERIZED PROCESS CONTROL SOFTWARE AGREEMENT

                             (LEASES AND SERVICES)


     This lease and service agreement, hereinafter "Agreement," is made and
entered into effective May 3, 1995, by and between ROFAN AUTOMATION AND
INFORMATION SYSTEMS B.V. (hereinafter "Lessor") and GRUPPO LEPETIT S.p.A.
(hereinafter "Lessee"), located at:

            LESSOR:   ROFAN AUTOMATION AND INFORMATION SYSTEMS B.V.

     Address:  Aert van Nesstraat 45
               3012 CA Rotterdam, The Netherlands

     Corporation of:  Kingdom of the Netherlands
 
     Authorized leasing representative for MOD5 SYSTEMS.

     LESSEE:   GRUPPO LEPETIT S.p.A.

     Address:  Via Roberto Lepetit 8
               20020 Lainate, Italy

     Corporation of:  Italy

     Lessor and Lessee hereby agree this Agreement consists in its entirety of
this executed covering document and the following attachments:

     APPENDIX A - SERVICE AGREEMENT

     APPENDIX B - MOD5 SPECIAL SERVICE ADDENDUM

     SCHEDULE 1 - LEASED MOD5 SOFTWARE

     Lessor agrees to lease to Lessee and Lessee agrees to lease from Lessor in
accordance with the terms and conditions of this Agreement MOD5 SOFTWARE as
delineated in Schedule 1 to integrally generate, transmit and manage process
control at the PLANTS listed in Schedule 1 attached hereto and made a part
hereof. This Agreement constitutes the entire understanding between Lessee and
Lessor pertaining to all MOD5 SOFTWARE for

                                      -1-
<PAGE>
 
Lessee's PLANTS and supersedes any prior or contemporaneous agreements and all
negotiations, representations and proposals written or oral pertaining to this
subject.

1.   Definitions
     -----------

     Terms used in this Agreement shall have the meanings ascribed to them as
follows:

1.1  Software Definitions
     --------------------

     (a) MOD5 SOFTWARE means (1) MOD5 CAN SOFTWARE, (2) SERIAL GRAPHICS
SOFTWARE, and (3) GPI based on specially designed, direct digital control,
redundant computer technology to provide process control and process operation
information for execution on MOD5 HARDWARE.

     (b) MOD5 SYSTEM is a specific implementation of MOD5 HARDWARE and MOD5
SOFTWARE in a PLANT.  Within a given PLANT there may be one or more MOD5
SYSTEMS.

     (c) MOD5 CAN SOFTWARE means MOD5 OVERHEADS including associated
FIRMWARE, DOWTRAN SUPPORT TOOLS, AND MOD5 COMPILER.

     (d) FIRMWARE is a physical means containing electronically retrievable
information pertaining to MOD5 SOFTWARE.
 
     (e) INTERFACE PROCESSOR is a functional interconnection within a
system between the MOD5 OVERHEADS and other MOD5 SOFTWARE, which contains
hardware, dedicated executable software, and FIRMWARE.

     (f) DOWTRAN is a specific language designed for the process control
application engineer to convert and express the CONTROL SCHEMA into an
APPLICATION PROGRAM for a manufacturing 

                                      -2-
<PAGE>
 
process. The APPLICATION PROGRAM is further transformed into COMPILED DOWTRAN
using MOD5 COMPILER.

     (g) MOD5 OVERHEADS means the redundantly deployed, executable operating
system software and, optionally, protocol use rights, for the MOD5 COMPUTER that
executes the COMPILED DOWTRAN and implements diagnostics, inputs, outputs,
alarms and event logging.

     (h) DOWTRAN SUPPORT TOOLS are utility programs which execute on the
MINICOMPUTER to assist the application engineer in writing the APPLICATION
PROGRAM in DOWTRAN.

     (i) APPLICATION PROGRAM is the set of sequential human readable
representations of the evolving CONTROL SCHEMA in DOWTRAN, where the set is
designated with an essentially consistent logical identifier.

     (j) COMPILED DOWTRAN is the set of respective sequential instances of
machine readable code, redundantly deployed, which results from the compilation
process executed by the MOD5 COMPILER to convert the APPLICATION PROGRAM written
in DOWTRAN into said machine readable code.

     (k) CONTROL SCHEMA comprises the entire collection of concepts,
process dynamics and control models, and associated decision models which are
referenced to define the APPLICATION PROGRAM.

     (l) MOD5 COMPILER is a computer program which executes on the
MINICOMPUTER to provide COMPILED DOWTRAN from the APPLICATION PROGRAM written in
the DOWTRAN language.
     
     (m) GPI means an executable subset of process information and related
software specially designed and developed for execution on the MINICOMPUTER
which displays and stores process 

                                      -3-
<PAGE>
 
information and related information to assist operations personnel.

     (n) SERIAL GRAPHICS SOFTWARE means Lessor supplied software,
associated FIRMWARE, and protocol use rights to implement SERIAL GRAPHICS.

1.2  Associated Hardware Definitions
     -------------------------------

     (a) MOD5 HARDWARE means a user defined hardware configuration designed to
implement the MOD5 CAN SOFTWARE which comprises two or more MOD CANS, two or
more MOD5 COMPUTERS, and one or more INTERFACE PROCESSORS. MOD5 HARDWARE further
comprises the Lessor specified hardware (excluding FIRMWARE) resident within the
MOD5 COMPUTER which is used in the linking of the MOD5 COMPUTER to at least one
INTERFACE PROCESSOR.

     (b) MOD CAN is a modular input/output device with associated
electronics which receives inputs and originates output relative to PLANT
instrumentation.

     (c) MOD5 COMPUTER is a Lessor specified, high speed control computer.
 
     (d) MINICOMPUTER is a member of a family of computers manufactured by
the Digital Equipment Corporation comprising VAX (or, optionally, AXP) hardware
executing the currently supported version of the VMS (or, optionally, Open VMS)
operating system specified by Lessor, said computers otherwise referred to as
VAX/VMS (or, optionally, AXP/Open VMS) systems, to be separately acquired by
Lessee.

     (e) SERIAL GRAPHICS is a programmable display panel means which
executes SERIAL GRAPHICS SOFTWARE for consistent holistic display of immediate
(REAL-TIME) information, within the context of a fixed pictorial background,
depicting the status of a set

                                      -4-
<PAGE>
 
of PROCESS CONTROL SIGNALS in the domain of a particular APPLICATION PROGRAM as
its derived COMPILED DOWTRAN executes on its affiliated redundant MOD5 COMPUTER
system. The SERIAL GRAPHICS programmable display panel system communicates with
its affiliated redundant MOD5 COMPUTER system using a network protocol.

1.3  Miscellaneous Definitions
     -------------------------

     (a) PROCESS CONTROL SIGNALS is the set of analog inputs, analog outputs,
digital inputs, digital outputs and the individual instances of process
variables contained within serial data messages transmitted to/from the MOD5
OVERHEADS utilized to implement an APPLICATION PROGRAM at a given PLANT.

     (b) HARDWARE CONSUMABLES include, without limitation, fuses, light bulbs,
chart paper and other such utility sundry items.

     (c) REMEDIAL PRODUCT NOTICE is a change in hardware design and/or
software design and/or announcements of procedures as may be desirable for
continuing effectiveness.
     
     (d) REAL-TIME is generally defined as a method of executing the MOD5
OVERHEADS in a MOD5 COMPUTER in which an event causes a given reaction within an
actual time limit and wherein MOD5 COMPUTER actions are specifically controlled
within the context of and by external conditions and actual times.
     
     (e) PLANT means Lessee's facilities referred to in the attached
Schedule 1.  MOD5 SYSTEMS for such PLANT are specified by the number of CANS,
and the installed version of computer processing unit(s), MOD5 OVERHEADS, GPI
and DOWTRAN respectively.
     
     (f) EFFECTIVE DATE is the date first set forth above.

                                      -5-
<PAGE>
 
2.   Term
     ----

     The Term of this Agreement shall begin on the EFFECTIVE DATE hereof and,
subject to the provisions herein for termination, shall continue for a period of
five (5) years.  Lessee may extend this Term for an additional six (6) months on
ninety (90) days advance notice.  Lessee may terminate this lease as to any MOD5
SYSTEM at any time during the Term of this agreement on ninety (90) days advance
written notice to Lessor.  The obligations of Article 6 shall survive any
expiration or accelerated termination of this Agreement for a period of ten (10)
years from the EFFECTIVE DATE.

3.   Payments
     --------

     3.1  Lease Charges.  Lease charges for MOD5 SOFTWARE leased hereunder are
set forth in the accompanying Schedule 1.  These charges shall be invoiced
within thirty (30) days of the EFFECTIVE DATE and upon each yearly anniversary
thereof during the term of this Agreement and shall be payable within thirty
(30) days of receipt of an invoice therefor.

     3.2  Taxes.  Lessee shall pay all taxes, however designated, which are
levied or based on the lease including, without limitation, property taxes,
local fees or excise taxes, but excluding taxes thereon based on income to
Lessor.  In the event Lessee defaults in the payment of any such tax, Lessor may
pay such tax and shall be reimbursed by Lessee, with interest, as additional
lease charges.

4.   Terms of Possession and Use
     ---------------------------

     4.1  Lessor and Lessee agree that all MOD5 SOFTWARE leased by Lessor
hereunder will be kept by Lessee in its sole possession and control and will at
all times be located at the PLANTS designated in the attached Schedule 1.  The
parties will 

                                      -6-
<PAGE>
 
mutually cooperate to keep Schedule 1 current as to installed MOD5 SYSTEMS at
each PLANT.

     4.2  Lessee shall enjoy all rights of possession and use of MOD5 SOFTWARE
leased hereunder subject to Lessor's rights under Paragraph 4.3, upon the
occurrence of one or more of the following conditions:

          (a) Lessee breaches the secrecy obligations of Article 6;
          
          (b) Lessee fails to make payments within sixty (60) days after notice
     of payments in arrears;

          (c) Lessee ceases to own or control facilities in which MOD5 SYSTEMS
     are installed, unless Lessee's transfer of ownership or control occurs
     pursuant to Article 14;

          (d) Lessee ceases to use MOD5 SYSTEMS, or uses them for a purpose
     other than their original installation, or modifies them by integrally
     combining internal MOD5 SYSTEM physical or logical components with systems
     of others with the proviso that when switching from a MOD5 SYSTEM to a
     different process control system at a given PLANT the MOD5 SYSTEM may be
     operated (as far as reasonably possible in decoupled status) in parallel
     with the other system;

          (e) Lessor is prevented by a Force Majeure condition from supporting
     MOD5 SOFTWARE acquired by Lessee hereunder.

          (f) Lessee terminates this Agreement totally or in part as to any MOD5
     SYSTEM.

                                      -7-
<PAGE>
 
     4.3  In the event one or more conditions of Paragraphs 4.2(a), (b), (c),
(d), or (e) occurs, Lessor may terminate this Agreement and its support of MOD5
SYSTEMS and MOD5 SOFTWARE shall be returned to Lessor. In the event Lessee
exercises rights of unilateral termination under Paragraph 4.2(f), Lessor will
terminate its support of such MOD5 SYSTEM and MOD5 SOFTWARE associated with such
SYSTEM shall be returned to Lessor, subject to Lessee rights specified in
Article 5. Lessee will permit reasonable access of Lessor to the PLANTS to
assist in the removal and return of MOD5 SOFTWARE.

5.   Lessor Property
     ---------------

     5.1  Lessor and Lessee agree that all MOD5 SOFTWARE leased hereunder
remains the personal property of Lessor or Lessor's grantor and, subject to
Lessee's reasonable operating, safety and secrecy requirements, Lessee shall
permit access of Lessor or Lessor's designee to the PLANTS at any time after
termination of this Agreement to permit removal of the same.  Lessee will keep
and maintain the MOD5 SOFTWARE free and clear of all liens, charges and
encumbrances.

     5.2  The glossaried and commented DOWTRAN language listing of the
APPLICATION PROGRAM produced by Lessee shall be considered derivative software
and, as such, it is owned by Lessee with the proviso that Lessee will diligently
pursue protecting Lessor's interests pursuant to Article 6. To facilitate
Lessee's understanding of the retained derivative APPLICATION PROGRAM, Lessee
may also retain the accompanying DOWTRAN application training manuals and any
cross references to sub-routine listings in the APPLICATION PROGRAM. Upon
expiration of this lease these written materials retained by Lessee shall be
considered proprietary information of Lessor licensed to Lessee subject to the
terms of Article 6. The compiled DOWTRAN listing from the MOD5 COMPILER is
property of and shall be returned to Lessor along with MOD5 SOFTWARE.

                                      -8-
<PAGE>
 
6.   Confidentiality
     ---------------

     6.1  MOD5 SYSTEMS comprise unique, valuable, proprietary information.
Lessee agrees to maintain and protect Lessor's interests in proprietary
information and will accordingly keep all information pertaining to MOD5 SYSTEMS
in confidence and not use the same except as is necessary to the enjoyment and
exercise of the leases granted by Lessor hereunder at the PLANTS listed in the
attached Schedule 1.  Lessee will take diligent action to fulfill the foregoing
obligations by instruction and agreement with its employees or agents respecting
the confidentiality of this information and shall obtain from them their written
commitments to comply with terms of confidentiality.

     6.2  Lessee shall adhere to the U.S. Export Administration Laws and
Regulations and shall not knowingly reexport, directly or indirectly, any MOD5
SOFTWARE or MOD5 HARDWARE, or any technical data received from Lessor or the
direct products of such technical data in violation of 15 CFR Part 779 of the
U.S. Export Administration Regulations unless proper authorization of the U.S.
Government and the written consent of Lessor have previously been obtained. No
law of conflicts or choice of law shall supersede this provision.

7.   Software Copies
     ---------------

     MOD5 SOFTWARE may only be copied, in whole or part, with proper inclusion
of Lessor's copyright notice and any other proprietary notice required by
Lessor, as necessary and incidental to the use of such software for archival and
backup purposes or to replace a worn or defective copy.  All such copies shall
be subject to the terms and conditions of this Agreement and shall be kept and
used at the designated PLANTS.  If Lessee is unable to operate the MOD5 SOFTWARE
on originally 

                                      -9-
<PAGE>
 
installed equipment, the MOD5 SOFTWARE may be transferred temporarily to another
system during the period of equipment malfunction.

8.   Warranties, Disclaimers and Validations
     ---------------------------------------

     8.1  THE EXPRESSED WARRANTIES HEREIN CONTAINED ARE IN LIEU OF ANY AND ALL
OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING THE WARRANTY OF MERCHANTABILITY
AND OF FITNESS FOR A PARTICULAR PURPOSE.  Lessor warrants that MOD5 SOFTWARE as
delivered will operate substantially as indicated in documentation provided by
Lessor and will replace or provide instructions to adjust malfunctioning
components of MOD5 SOFTWARE on receiving notice thereof from Lessee.  Lessor
will expeditiously address the notice with, alternatively at Lessor's
discretion, replacement of the component with a currently available MOD5
SOFTWARE component or instructions for corrective logical modification of, or
other accommodative procedure for, the MOD5 SOFTWARE addressing the malfunction.
Lessee shall promptly, upon discovery, notify Lessor of any alleged deficiency
which may exist.

     8.2  Lessor warrants that the MOD5 SOFTWARE as delivered by Lessor under
this Agreement shall not infringe copyrights or patent rights of a third party
existing on the EFFECTIVE DATE.  Upon prompt written notice from Lessee
providing all pertinent details of a claim of such asserted infringement, Lessor
will undertake to investigate and at Lessor's expense to settle or to defend
against such a claim, provided Lessee grants any necessary authority and gives
its full support and cooperation, or to obtain the right for Lessee to continue
to use the MOD5 SOFTWARE, or to replace or modify the allegedly infringing
components of the MOD5 SOFTWARE which Lessor has so delivered to avoid any such
claim that is found to be valid.  Without prejudice to the generality of the
foregoing, such expense shall extend to reasonable attorneys' fees incurred by
Lessee in 

                                      -10-
<PAGE>
 
respect of such claim.  If an award is rendered against Lessee, in any
litigation that the Lessor defends hereunder for infringement by the components
of the MOD5 SOFTWARE which Lessor has so delivered, then Lessor shall reimburse
Lessee for damages and costs awarded by the judicial authority in respect to
those components.

     8.3  Lessee acknowledges that it is responsible for each APPLICATION
PROGRAM and is not relying on Lessor's skill or judgment to select or furnish
MOD5 SOFTWARE and associated MOD5 HARDWARE suitable for operation of a
particular manufacturing process and that there are no warranties which are not
contained in this Agreement. Lessee acknowledges that it has made the selection
of the associated MOD5 HARDWARE. Lessor shall not be liable for special,
incidental or consequential damages arising out of or in connection with the
performance of systems utilizing MOD5 SOFTWARE and associated MOD5 HARDWARE.
Lessor shall not be responsible for any loss or damage caused by, nor shall any
payments due hereunder abate by reason of, any interruption in or loss of
service or sue of the equipment or any part thereof arising from any reason not
solely attributable to Lessor. Without limiting the generality of the foregoing,
examples of the foregoing include errors in the APPLICATION PROGRAM, normal wear
and tear of the MOD5 SOFTWARE, or gradual deterioration of the MOD5 SOFTWARE.

     8.4  Lessor's total obligation after the EFFECTIVE DATE under this Article
shall in no event exceed one hundred percent (100%) of the total amount of the
payments actually received by Lessor under this Agreement.

     8.5  Whenever and to the extent validation of MOD5 SYSTEMS has occurred
under FDA regulations to date, Lessee shall retain those reports in support of
validation.  If revalidation of the process control system is necessary because
of extended 

                                      -11-
<PAGE>
 
requirements of the FDA regulations, Lessor shall provide information reasonably
required.

     8.6  With regard to any FDA validations in progress, or those to be
conducted in the future, Lessor shall provide information reasonably required
under FDA regulations with respect to MOD5 SYSTEMS validation.

9.   Liability, Indemnity and Risk of Loss
     -------------------------------------

     Lessee assumes all risks and liabilities, whether or not covered by
insurance, and shall indemnify and hold Lessor and its employees harmless for
any liability, claim, loss, damage or expense for injuries to or deaths of
persons and for damage to property, howsoever arising from or incident to the
possession, use, operation or storage of MOD5 SOFTWARE and associated MOD5
HARDWARE, and operation of the MOD5 SYSTEM, save and except for any matter
attributable to the sole negligence or willful misconduct of Lessor.  Said
assumption of risks and liabilities by Lessee shall apply whether such injury or
death to persons be to agents or employees of Lessee or be to third persons and
whether such damage be to property of Lessee or to property of others.

10.  MOD5 SOFTWARE Maintenance and Support
     -------------------------------------

     10.1 Throughout the Term hereunder after installation of the MOD5 SOFTWARE,
Lessee shall maintain site conditions to provide an acceptable operating
environment for the MOD5 SOFTWARE as referenced in documentation provided by
Lessor.  Lessee is responsible for maintenance not provided under the Service
Agreement attached hereto as Appendix A and installation of the MOD5 SOFTWARE.
Lessee will maintain the MOD5 SOFTWARE in a current and up-to-date condition
adapting the APPLICATION PROGRAM to accommodate REMEDIAL PRODUCT NOTICES when
recommended by Lessor, which will be supplied by Lessor or by vendors 

                                      -12-
<PAGE>
 
approved by Lessor. Such adaptations will normally address operating
reliability. Lessor will counsel Lessee, as requested pursuant to the attached
Service Agreement, to accomplish the foregoing and Lessee shall permit Lessor or
Lessor's designee access to the MOD5 SOFTWARE for providing any necessary
assistance, such access to include network access if deemed appropriate.

     10.2     Lessor agrees to supply Maintenance and Support Services for MOD5
SOFTWARE, including maintenance and adjustment of associated MOD5 HARDWARE,
solely in accordance with the Service Agreement which is incorporated as
Appendix A of this Agreement.  Lessor is not responsible for supply, maintenance
and adjustment of the MINICOMPUTER, and other commercially sourced computer(s)
or commercially sourced operating system(s) used in association with MOD5
SOFTWARE.

     10.3  Subject to Lessee's reasonable operating, safety and secrecy
requirements, Lessee shall grant Lessor PLANT access to the MINICOMPUTER and
other commercially sourced computer(s) used with MOD5 SOFTWARE during normal
working hours for inspection and installation of REMEDIAL PRODUCT NOTICES and
for any other reasonable purpose, such access to include network access if
deemed appropriate.  Lessee shall immediately notify Lessor of all details
concerning any malfunction arising out of the alleged or apparent improper
manufacture, functioning or operation of the MOD5 SOFTWARE.

11.  Notices
     -------

     Lessee and Lessor agree that notices required hereunder shall be
deemed received the seventh day after mailing, if mailed air postage prepaid to
Lessor or Lessee as the case may be at their respective address given below.

                                      -13-
<PAGE>
 
     If to Lessor, to:

                         Rofan Automation and Information
                              Systems B.V.
                         P.O. Box 48
                         4530 AA Terneuzen, The Netherlands

                         Attention:  Hans Naninck, Director

     If to Lessee, to:

                         Gruppo Lepetit S.p.A.
                         Via Roberto Lepetit 8
                         20020 Lainate, Italy

                         Attention:_________________________

Either party may change such address for notice by sending to the other party a
written notice.

12.  Severability
     ------------

     Any provision hereof prohibited by, or unlawful or unenforceable under, any
applicable law of any jurisdiction shall be ineffective as to such jurisdiction
without invalidating the remaining provisions of this Agreement.  In the event a
material provision is affected, the parties shall reformulate their mutual
undertakings in such manner as to preserve, as much as possible, their original
intentions and objects of this Agreement, consistent with the laws of such
jurisdiction.

13.  Alterations
     -----------

     Except for Lessee's remedial modification of APPLICATION PROGRAM, no
alterations to MOD5 SOFTWARE shall be made without first obtaining in each
instance the prior written approval of Lessor which approval shall be
expeditiously considered and not be unreasonably withheld.

                                      -14-
<PAGE>
 
14.  Conflicts and Assignability
     ---------------------------

     This Agreement does not operate as an acceptance of any conflicting terms
or conditions and shall prevail over any conflicting provision of any subsequent
purchase order or other instrument of Lessee, it being understood that any
purchase order or the request of Lessee acted upon by Lessor shall be for the
convenience of Lessee only but shall not operate to amend or modify in any
respect the terms hereof. This Agreement may only be altered, modified,
supplemented or deviated from by further agreement in writing executed by an
authorized representative of each Lessor and Lessee. Lessee and Lessor
acknowledge that by executing this Agreement each has reviewed the attachments
listed above and each agrees to be legally bound and dutifully perform its
obligations thereunder. Lessor reserves the right to assign this Agreement to a
parent, affiliate or sister company of Lessor, but otherwise this Agreement
shall not be assignable by either party except to a successor of the entire
PLANT, which undertakes all obligations assumed by Lessee hereunder by an
agreement executed and copied to Lessor and to whom Lessor has no reasonable
objection.

15.  Applicable Law
     --------------

     The laws of the Kingdom of the Netherlands shall be applied in the
construction and interpretation of this Agreement.  No law of conflicts or
choice of law shall supersede this provision except as provided in Article 6.

                                      -15-
<PAGE>
 
     IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
on their behalf by their duly authorized representatives.
 

LESSOR:                                  LESSEE:

ROFAN AUTOMATION AND
INFORMATION SYSTEMS B.V.                 GRUPPO LEPETIT S.p.A.


By: /s/ John C. Lillich             By: /s/ Helio Giglio
   -----------------------             ----------------------------

Name:   John C. Lillich             Name:   Helio Giglio           
     ---------------------               --------------------------

Title:  Attorney In Fact            Title:  Controller              
      --------------------                -------------------------

Date:   May 3, 1995                 Date:   May 3rd, 1995           
     ---------------------               --------------------------



By: /s/ Jane M. Gootee        
   -----------------------             

Name:   Jane M. Gootee      
     ---------------------             

Title:  Attorney In Fact   
      --------------------             

Date:   May 3, 1995         
     ---------------------             

                                      -16-
<PAGE>
 
                                  APPENDIX A
                                  ----------

                               SERVICE AGREEMENT

                                  MAINTENANCE

1.   Services
     --------

     (i) To facilitate efficient use of MOD5 SOFTWARE, Lessor agrees to provide
and Lessee agrees to acquire MOD5 SOFTWARE Maintenance Services as provided
hereunder.  Lessee has responsibility to acquire, through separate arrangements
with Lessor or another party, reasonable MOD5 HARDWARE training and/or services
necessary to apply DOWTRAN to the CONTROL SCHEMA and to remedially modify an
APPLICATION PROGRAM.

     (ii)  Maintenance Services for MOD5 SOFTWARE include the notification of
and assistance for implementation, where necessary, of REMEDIAL PRODUCT NOTICES
for MOD5 SOFTWARE and remedial maintenance consultation for MOD5 SOFTWARE, MOD5
HARDWARE, FIRMWARE and other maintenance conducted by Lessee.  Repair of
subassemblies and printed circuit boards will by done by Lessor for Lessee's
account, i.e., at Lessee's expense, working with the vendor of such components.
Acquisition and installation of HARDWARE CONSUMABLES shall be the responsibility
of Lessee.

     (iii)  Lessor shall provide backup support for MOD5 SOFTWARE and MOD5
HARDWARE after Lessee has undertaken reasonable effort to resolve any MOD5-
related problem.  Telephone support shall be provided within 24 hours of
notification of the problem and on-site service shall be provided within 48
hours of any such notification.

     (iv)  Lessee shall be responsible for the appointment of one or more
computer systems professionals or process control professionals fluent in the
English language having a level of 

                                      -17-
<PAGE>
 
technical qualifications and experience acceptable to Lessor, whose acceptance
will not be unreasonably withheld, as manager for the MOD5 SOFTWARE. The MOD5
SOFTWARE manager shall enter into a secrecy agreement with Lessor to protect
Lessor's technology and shall cooperate with Lessor in enabling access to the
MOD5 SOFTWARE when appropriate.

     (v)  "Special Services" reasonably required by Lessee at its PLANT sites
any time during the Term and upon termination of this lease, such as, for
example, services that may be required to assist Lessee in completing FDA
validations of process control in progress or for such technical support as may
be reasonably necessary in switching from MOD5 process control to another
process control system shall be provided by Lessor on reasonable notice for a
period up to twelve (12) workdays (8 hours per workday) over each successive
twelve (12) month period during the term of this lease measured from its
EFFECTIVE DATE. Special Service workdays not used within a given twelve (12)
month period shall not carry over to a subsequent period.

     (vi)  Lessee and Lessor from time to time may agree on additional or new
Special Services beyond those agreed in this Agreement.  Any such additional or
new special Services may be agreed to in a MOD5 Special Service Addendum.  For
each separate request for services from Lessee, Lessor shall prepare and submit
to Lessee a written service proposal.  The parties shall discuss the service
proposal and negotiate to agreement regarding the nature, scope, terms and
detail of the work.  If agreement on the total scope is reached, the parties
shall develop a Special Service Addendum which shall define in detail the scope
of services and tasks to be performed, the schedule for completion and the
billing basis for such Special Services.  Each MOD5 Special Service Addendum
shall be effective only if signed by an authorized representative of each party.
Each Special Service Addendum shall be sequentially numbered.  A sample Special
Service Addendum is attached as Appendix B.

                                      -18-
<PAGE>
 
2.  Service Limitations
    -------------------

     Services are contingent upon the proper use of the MOD5 SOFTWARE and the
acquisition of associated MOD5 HARDWARE suitable for running MOD5 SOFTWARE.
Services do not include any of the following: electrical work external to the
INTERFACE PROCESSOR, MINICOMPUTER, or other commercially sourced computer(s) or
commercially sourced operating system(s) associated with the MOD5 SYSTEM;
replacing or providing HARDWARE CONSUMABLES; refinishing MOD5 SOFTWARE; or
maintenance of accessories, attachments, machines or other devices not provided
by Lessor. Service shall not include practices which in Lessor's judgment are
unsafe or impractical for Lessor to render because of alterations to the MOD5
SOFTWARE or connection of the PLANTS by mechanical or electrical means to
machine devices furnished by a supplier other than Lessor. Service will not be
performed on MOD5 SOFTWARE located in an unsafe or hazardous environment, as
determined by Lessor. Service to be provided does not include service
necessitated by elements external to the MOD5 SOFTWARE which are not within
Lessor.s operation or maintenance instructions or installation site preparation
guidelines including, but not limited to, humidity, temperature, power failure,
surges, air conditioning, grounding, static charge control, service resulting
from accident, neglect, alterations, improper use or misuse of the MOD5 SOFTWARE
or by repairs attempted by Lessee's personnel or service to a version other than
the installed version of MOD5 SOFTWARE and MOD5 HARDWARE.

3.   Service Charges
     ---------------

     (i)  For Maintenance Services described in Article 1 performed at Lessee's
PLANTS, Lessee shall pay Lessor a service charge in the amount of Lessor's
standard charge for such 

                                      -19-
<PAGE>
 
services, plus reasonable travel and living expenses. This fee is presently U.S.
$125.00 per hour.

     (ii)  For home based maintenance and support services described in Article
1 above conducted at the home locations of Lessor and its suppliers, Lessee
shall pay Lessor an annual fee as shown on Schedule 1 determined by multiplying
the total number of MOD CANS  on which MOD5 SOFTWARE is run by a standard
service fee in U.S. Dollars.

     (iii)  Special Services pursuant to Article 1(v) shall be without charge
for up to 2 workdays in a single visit within each successive 12 month period
during the Term of this lease.  For additional workdays and additional visits
within each 12 month period Lessee shall pay Lessor a professional consulting
fee of U.S. $150.00 per hour for up to an additional 10 workdays.  Lessee shall
reimburse Lessor for reasonable travel and lodging expenses of such consultancy.

     (iv)  Service charges accruing under this Article 3 will be invoiced and
shall be payable within thirty (30) days of receipt of an invoice therefor.
Payment for services shall be in U.S. Dollars. In the case of expenses incurred
in another currency, such expenses shall first be translated by Lessor into U.S.
Dollars using the daily average rate quoted in Amsterdam by Bank Mendes Gans for
purchase of U.S. Dollars with the expense currency on the date of invoice, and
then invoiced in U.S. Dollars to Lessee.

                                      -20-
<PAGE>
 
                                   APPENDIX B
                                   ----------

                    MOD5 SPECIAL SERVICE ADDENDUM NO._____
                     (Reference Article 1(vi) Appendix A)


(A)  Scope of Special Services:







(B)  Compensation:







(C)  Term or Schedule of Completion:
<PAGE>
 
(D)  Changes to Scope of Services:







(E)  Representatives:







(F)  Responsibility for Reporting:







(G)  Termination:

     This Special Service Addendum may be terminated (i) by either party with or
     without cause at any time upon 30 days written notice, or (ii) by the non-
     breaching party upon 2 days written notice in the event the other party
     fails to cure its breach of a material obligation under the Agreement or
     this Special Service Addendum within 20 days of its receipt of a notice
     alleging such breach from the other party.  
<PAGE>
 
     Upon termination of the Special Service Addendum, Lessor shall invoice
     Lessee for all services performed by Lessor under this Special Service
     Addendum prior to the termination for which Lessor was not previously
     compensated, and for expenses necessary to shut down the project.

ACCEPTED AND AGREED, as of the later of the two dates noted in the signature
blocks, by each Party's authorized representative.


Lessor:                                  Lessee:

ROFAN AUTOMATION AND                     GRUPPO LEPETIT S.p.A.
INFORMATION SYSTEMS B.V.


By:                                      By:
   -------------------------                ----------------------

Name:                                    Name:
     -----------------------                  --------------------

Title:                                   Title:
      ----------------------                   -------------------

Date:                                    Date:
     -----------------------                  --------------------
<PAGE>
 
                                  SCHEDULE 1
                                  ----------

                             LEASED MOD5 SOFTWARE
                             --------------------

<TABLE>
<CAPTION>
                             NUMBER OF       LEASE               ANNUAL
SITE          PLANT          MOD CANS       CHARGES           SUPPORT FEES
- ----          -----          ---------      -------           ------------
<S>           <C>            <C>         <C>                  <C>         
 
BRINDISI,     FERMENTATION        5          NONE             U.S.$6,500.00
ITALY                                    (ANTEDATES LEASING)
 
MOD5 SYSTEM DESCRIPTION:
- ------------------------
 
 NUMBER OF SYSTEMS:    1
 
 VERSION:
  CPU:                 MOD5+
  OVERHEAD SOFTWARE:   REL.0643
  GPI:                 REL.V2.00
  DSS:                 REL.V2.00
  MODSERVER
   HARDWARE:           AS STADE STANDARD
   SOFTWARE:           REL.V2.0e
 
 
BRINDISI,     RIFA RECOVERY       2      U.S.$16,800.00       U.S.$2,600.00
ITALY
                                  5          NONE             U.S.$6,500.00
                                         (ANTEDATES LEASING)
 
MOD5 SYSTEMS DESCRIPTION:
- -------------------------
 
 NUMBER OF SYSTEMS:    2
 
 VERSION:
  CPU:                 MOD5+
  OVERHEAD SOFTWARE:   REL.0643
  GPI:                 REL.V2.00
  DSS:                 REL.V2.00
  MODSERVER
   HARDWARE:           AS STADE STANDARD
   SOFTWARE:           REL.V2.0e
</TABLE> 




                               PAGE 1 OF 3 PAGES
<PAGE>
 
<TABLE>
<CAPTION>
                             NUMBER OF       LEASE               ANNUAL
SITE          PLANT          MOD CANS       CHARGES           SUPPORT FEES
- ----          -----          ---------      -------           ------------
<S>           <C>            <C>         <C>                  <C>         
 
BRINDISI,     CHEMICAL            2      U.S.$16,800.00       U.S.$2,600.00
ITALY         DEVELOPMENT                                     
              PILOT


 
MOD5 SYSTEM DESCRIPTION:
- ------------------------
 
 NUMBER OF SYSTEMS:    1
 
 VERSION:
  CPU:                 MOD5+
  OVERHEAD SOFTWARE:   REL.0643
  GPI:                 REL.V2.00
  DSS:                 REL.V2.00
  MODSERVER
   HARDWARE:           AS STADE STANDARD
   SOFTWARE:           REL.V2.0e
 
 
GARESSIO,     BUILDING 1          8 +           NONE          U.S.$11,700.00
ITALY                             1 SPARE   (ANTEDATES LEASING)

 
MOD5 SYSTEMS DESCRIPTION:
- -------------------------
 
 NUMBER OF SYSTEMS:    2 + 1 SPARE
 
 VERSION:
  CPU:                 MOD5+ *
  OVERHEAD SOFTWARE:   COMPILER VERSION 6.43**
  GPI:                 2.11
  DSS:                 VAX VMS 5.5-2
</TABLE> 
 
 *CPU MOD5+ TO BE REPLACED WITH MOD5E BY JULY 1995.

**A CHANGE TO COMPILER VERSION 7.7 IS PLANNED.




                               PAGE 2 OF 3 PAGES
<PAGE>
 
<TABLE>
<CAPTION>
                             NUMBER OF       LEASE               ANNUAL
SITE          PLANT          MOD CANS       CHARGES           SUPPORT FEES
- ----          -----          ---------      -------           ------------
<S>           <C>            <C>         <C>                  <C>         
 
GARESSIO,     DISTILLERY          2           NONE            U.S.$2,600.00
ITALY                                    (ANTEDATES LEASING)  
                       

                                  1      U.S.$8,400.00        U.S.$1,300.00
                             (TO BE INSTALLED
                             BY JUNE 1995)



 
MOD5 SYSTEM DESCRIPTION:
- ------------------------
 
 NUMBER OF SYSTEMS:    1
 
 VERSION:
  CPU:                 MOD5+*
  OVERHEAD SOFTWARE:   COMPILER VERSION 6.43**
  GPI:                 2.11
  DSS:                 VAX VMS 5.5-2


 *CPU MOD5+ TO BE REPLACED WITH MOD5E BY JULY 1995.

**A CHANGE TO COMPILER VERSION 7.7 IS PLANNED.


                                         --------------       --------------
         TOTAL ANNUAL LEASE CHARGES:     U.S.$42,000.00

         TOTAL ANNUAL SUPPORT FEES:                           U.S.$33,800.00
</TABLE> 




                               PAGE 3 OF 3 PAGES
<PAGE>
 
                      PERSONAL CONFIDENTIALITY AGREEMENT
                      ----------------------------------


DECLARATIONS:


     The undersigned employee of GRUPPO LEPETIT S.p.A. (Gruppo) has certain
responsibilities for maintaining and operating MOD5 SYSTEMS for manufacturing
process control.

     The undersigned Affiliate of The Dow Chemical Company (Dow) is willing to
continue supporting MOD5 SYSTEMS used by Gruppo according to the terms of the
"Computerized Process Control Software Agreement" entered into between Affiliate
and Gruppo with the proviso that the latter appoint a MOD5 SOFTWARE technical
manager with appropriate competencies in the English language and pertinent
technical qualifications.


ASSURANCES:

     The undersigned acknowledges he/she has been assigned such responsibilities
regarding MOD5 SYSTEMS by Gruppo and affirms:

     1.   That he/she is familiar with the "Computerized Process Control
Software Agreement" mentioned above, including those terms thereof regarding
confidentiality of Information.

     2.   That pursuant to the terms of the Agreement he/she will not disclose
to others proprietary information about MOD5 SYSTEMS nor make any unauthorized
copies of documents containing such Information, and moreover agrees that no
personal rights to use any Information acquired in working with MOD5 SYSTEMS are
expressly or impliedly acquired hereunder.

     It is understood by the undersigned and Affiliate of Dow that these
obligations shall not apply to Information which is or becomes part of the
public domain through no fault of the undersigned or is received by the
undersigned on a nonconfidential basis from a third party who is not under an
obligation of confidence to Dow or a Dow Affiliate.


ACCEPTED BY                              ROFAN AUTOMATION AND
Gruppo Representative:                   INFORMATION SYSTEMS B.V.

                                                                 
                                                                       
                                         By:
- ---------------------------                 ----------------------------
Name:                                    Name:                       
     ----------------------                   --------------------------

Title:                                   Title:                       
      ---------------------                    -------------------------

Date:                                    Date:
     ----------------------                   --------------------------

<PAGE>
 
                COMPUTERIZED PROCESS CONTROL SOFTWARE AGREEMENT
                             (LEASES AND SERVICES)


     This lease and service agreement, hereinafter "Agreement," is made and
entered into effective May 3, 1995, by and between ROFAN AUTOMATION AND
INFORMATION SYSTEMS B.V. (hereinafter "Lessor") and BIOCHIMICA DEL SALENTO
S.p.A. (hereinafter "Lessee"), located at:



     LESSOR:   ROFAN AUTOMATION AND INFORMATION SYSTEMS B.V.

     Address:  Aert van Nesstraat 45
               3012 CA Rotterdam, The Netherlands

     Corporation of:  Kingdom of the Netherlands

     Authorized leasing representative for MOD5 SYSTEMS.

     LESSEE:   BIOCHIMICA DEL SALENTO S.p.A.

     Address:  Via Murat 25
               20159, Milan, Italy

     Corporation of:  Italy


     Lessor and Lessee hereby agree this Agreement consists in its entirety of
this executed covering document and the following attachments:

     APPENDIX A - SERVICE AGREEMENT

     APPENDIX B - MOD5 SPECIAL SERVICE ADDENDUM

     SCHEDULE 1 - LEASED MOD5 SOFTWARE


     Lessor agrees to lease to Lessee and Lessee agrees to lease from Lessor in
accordance with the terms and conditions of this Agreement MOD5 SOFTWARE as
delineated in Schedule 1 to integrally generate, transmit and manage process
control at the PLANTS listed in Schedule 1 attached hereto and made a part
hereof.  This Agreement constitutes the entire understanding between
Lessee and Lessor pertaining to all MOD5 SOFTWARE for 

                                      -1-
<PAGE>
 
Lessee's PLANTS and supersedes any prior or contemporaneous agreements and all
negotiations, representations and proposals written or oral pertaining to this
subject.

1.   Definitions
     -----------

     Terms used in this Agreement shall have the meanings ascribed to them as
follows:

1.1  Software Definitions

     (a) MOD5 SOFTWARE means (1) MOD5 CAN SOFTWARE, (2) SERIAL GRAPHICS
SOFTWARE, and (3) GPI based on specially designed, direct digital control,
redundant computer technology to provide process control and process operation
information for execution on MOD5 HARDWARE.

     (b) MOD5 SYSTEM is a specific implementation of M0D5 HARDWARE and MOD5
SOFTWARE in a PLANT.  within a given PLANT there may be one or more MOD5
SYSTEMS.

     (c) MOD5 CAN SOFTWARE means MOD5 OVERHEADS including associated FIRMWARE,
DOWTRAN SUPPORT TOOLS, and MOD5 COMPILER.

     (d) FIRMWARE is a physical means containing electronically retrievable
information pertaining to MOD5 SOFTWARE.

     (e) INTERFACE PROCESSOR is a functional interconnection  within a system
between the MOD5 OVERHEADS and other MOD5 SOFTWARE, which contains hardware,
dedicated executable software, and FIRMWARE.

     (f) DOWTRAN is a specific language designed for the process control
application engineer to convert and express the CONTROL SCHEMA into an
APPLICATION PROGRAM for a manufacturing

                                      -2-
<PAGE>
 
process. The APPLICATION PROGRAM is further transformed into COMPILED DOWTRAN
using a MOD5 COMPILER.

     (g) MOD5 OVERHEADS means the redundantly deployed, executable operating
system software and, optionally, protocol use rights, for the MOD5 COMPUTER that
executes the COMPILED DOWTRAN and implements diagnostics, inputs, outputs,
alarms and event logging.
     
     (h) DOWTRAN SUPPORT TOOLS are utility programs which execute on the
MINICOMPUTER to assist the application engineer in writing the APPLICATION
PROGRAM in DOWTRAN.

     (i) APPLICATION PROGRAM is the set of sequential human readable
representations of the evolving CONTROL SCHEMA in DOWTRAN, where the set is
designated with an essentially consistent logical identifier.

     (j) COMPILED DOWTRAN is the set of respective sequential instances of
machine readable code, redundantly deployed, which results from the compilation
process executed by the MOD5 COMPILER to convert the APPLICATION PROGRAM written
in DOWTRAN into said machine readable code.

     (k) CONTROL SCHEMA comprises the entire collection of concepts, process
dynamics and control models, and associated decision models which are referenced
to define the APPLICATION PROGRAM.

     (l) MOD5 COMPILER is a computer program which executes on the MINICOMPUTER
to produce COMPILED DOWTRAN from the APPLICATION PROGRAM written in the DOWTRAN
language.

     (m) GPI means an executable subset of process information and related
software specially designed and developed for execution on the MINICOMPUTER
which displays and stores process 

                                      -3-
<PAGE>
 
information and related information to assist operations personnel.

     (n) SERIAL GRAPHICS SOFTWARE means Lessor supplied software, associated
FIRMWARE, and protocol use rights to implement SERIAL GRAPHICS.

1.2  Associated Hardware Definitions

     (a) MOD5 HARDWARE means a user defined hardware configuration designed to
implement the MOD5 CAN SOFTWARE which comprises two or more MOD CANS, two or
more MOD5 COMPUTERS, and one or more INTERFACE PROCESSORS.  MOD5 HARDWARE
further comprises the Lessor specified hardware (excluding FIRMWARE) resident
within the MOD5 COMPUTER which is used in the linking of the MOD5 COMPUTER to at
least one INTERFACE PROCESSOR.

     (b) MOD CAN is a modular input/output device with associated electronics
which receives inputs and originates output relative to PLANT instrumentation.

     (c) MOD5 COMPUTER is a Lessor specified, high speed control computer.

     (d) MINICOMPUTER is a member of a family of computers manufactured by the
Digital Equipment Corporation comprising VAX (or, optionally, AXP) hardware
executing the currently supported version of the VMS (or, optionally, Open VMS)
operating system specified by Lessor, said computers otherwise referred to as
VAX/VMS (or, optionally, AXP/Open VMS) systems, to be separately acquired by
Lessee.

     (e) SERIAL GRAPHICS is a programmable display panel means which executes
SERIAL GRAPHICS SOFTWARE for consistent holistic display of immediate (REAL-
TIME) information, within the context of a fixed pictorial background, depicting
the status of a set 

                                      -4-
<PAGE>
 
of PROCESS CONTROL SIGNALS in the domain of a particular APPLICATION PROGRAM as
its derived COMPILED DOWTRAN executes on its affiliated redundant MOD5 COMPUTER
system. The SERIAL GRAPHICS programmable display panel system communicates with
its affiliated redundant MOD5 COMPUTER system using a network protocol.

1.3  Miscellaneous Definitions
     -------------------------

     (a) PROCESS CONTROL SIGNALS is the set of analog inputs, analog outputs,
digital inputs, digital outputs and the individual instances of process
variables contained within serial data messages transmitted to/from the MOD5
OVERHEADS utilized to implement an APPLICATION PROGRAM at a given PLANT.

     (b) HARDWARE CONSUMABLES include, without limitation, fuses, light bulbs,
chart paper and other such utility sundry items.

     (c) REMEDIAL PRODUCT NOTICE is a change in hardware design and/or software
design and/or announcements of procedures as may be desirable for continuing
effectiveness.

     (d) REAL-TIME is generically defined as a method of executing the MOD5
OVERHEADS in a MOD5 COMPUTER in which an event causes a given reaction within an
actual time limit and wherein M0D5 COMPUTER actions are specifically controlled
within the context of and by external conditions and actual times.

     (e) PLANT means Lessee's facilities referred to in the attached Schedule 1.
MOD5 SYSTEMS for each PLANT are specified by the number of CANS, and the
installed version of computer processing unit(s), MOD5 OVERHEADS, CPI and
DOWTRAN respectively.

     (f) EFFECTIVE DATE is the date first set forth above.

                                      -5-
<PAGE>
 
2.   Term
     ----

     The Term of this Agreement shall begin on the EFFECTIVE DATE hereof and,
subject to the provisions herein for termination, shall continue for a period of
five (5) years.  Lessee may extend this Term for an additional six (6) months on
ninety (90) days advance notice.  Lessee may terminate this lease as to any MOD5
SYSTEM at any time during the Term of this agreement on ninety (90) days advance
written notice to Lessor.  The obligations of Article 6 shall survive any
expiration or accelerated termination of this Agreement for a period of ten (10)
years from the EFFECTIVE DATE.

3.   Payments
     --------

     3.1  Lease Charges  Lease charges for MOD5 SOFTWARE leased hereunder are
set forth in the accompanying Schedule 1. These charges shall be invoiced within
thirty (30) days of the EFFECTIVE DATE and upon each yearly anniversary thereof
during the term of this Agreement and shall be payable within thirty (30) days
of receipt of an invoice therefor.

     3.2  Taxes  Lessee shall pay all taxes, however designated, which are
levied or based on the lease including, without limitation, property taxes,
local fees or excise taxes, but excluding taxes thereon based on income to
Lessor.  in the event Lessee defaults in the payment of any such tax, Lessor may
pay such tax and shall be reimbursed by Lessee, with interest, as additional
lease charges.

4.   Terms of Possession and Use
     ---------------------------

     4.1  Lessor and Lessee agree that all MOD5 SOFTWARE leased by Lessor
hereunder will be kept by Lessee in its sole possession and control and will at
all times be located at the PLANTS designated in the attached Schedule 1.  The
parties will 

                                      -6-
<PAGE>
 
mutually cooperate to keep Schedule 1 current as to installed MOD5 SYSTEMS at
each PLANT.

     4.2  Lessee shall enjoy all rights of possession and use of MOD5 SOFTWARE
leased hereunder subject to Lessor's rights under Paragraph 4.3, upon the
occurrence of one or more of the following conditions:

          (a) Lessee breaches the secrecy obligations of Article 6;

          (b) Lessee fails to make payments within sixty (60) days after notice
     of payments in arrears;

          (c) Lessee ceases to own or control facilities in which MOD5 SYSTEMS
     are installed, unless Lessee's transfer of ownership or control occurs
     pursuant to Article 14;

          (d) Lessee ceases to use MOD5 SYSTEMS, or uses them for a purpose
     other than their original installation, or modifies them by integrally
     combining internal MOD5 SYSTEM physical or logical components with systems
     of others with the proviso that when switching from a MOD5 SYSTEM to a
     different process control system at a given PLANT the MOD5 SYSTEM may be
     operated (as far as reasonably possible in decoupled status) in parallel
     with the other system;

          (e) Lessor is prevented by a Force Majeure condition from supporting
     MOD5 SOFTWARE acquired by Lessee hereunder.

          (f) Lessee terminates this Agreement totally or in part as to any MOD5
     SYSTEM.

                                      -7-
<PAGE>
 
     4.3  In the event one or more conditions of Paragraphs 4.2(a), (b), (c),
(d), or (e) occurs, Lessor may terminate this Agreement and its support of MOD5
SYSTEMS and MOD5 SOFTWARE shall be returned to Lessor. In the event Lessee
exercises rights of unilateral termination under Paragraph 4.2(f), Lessor will
terminate its support of such MOD5 SYSTEM and MOD5 SOFTWARE associated with such
SYSTEM shall be returned to Lessor, subject to Lessee rights specified in
Article 5. Lessee will permit reasonable access of Lessor to the PLANTS to
assist in the removal and return of MOD5 SOFTWARE.

5.   Lessor Property
     ---------------

     5.1  Lessor and Lessee agree that all MOD5 SOFTWARE leased hereunder
remains the personal property of Lessor or Lessor's grantor and, subject to
Lessee's reasonable operating, safety and secrecy requirements, Lessee shall
permit access of Lessor or Lessor's designee to the PLANTS at any time after
termination of this Agreement to permit removal of the same.  Lessee will keep
and maintain the MOD5 SOFTWARE free and clear of all liens, charges and
encumbrances.

     5.2  The glossaried and commented DOWTRAN language listing of the
APPLICATION PROGRAM produced by Lessee shall be considered derivative software
and, as such, it is owned by Lessee with the proviso that Lessee will diligently
pursue protecting Lessor's interests pursuant to Article 6.  To facilitate
Lessee's understanding of the retained derivative APPLICATION PROGRAM, Lessee
may also retain the accompanying DOWTRAN application training manuals and any
cross references to sub-routine listings in the APPLICATION PROGRAM.  Upon
expiration of this lease these written materials retained by Lessee shall be
considered proprietary information of Lessor licensed to Lessee subject to the
terms of Article 6.  The compiled DOWTRAN listing from the MOD5 COMPILER is
property of and shall be returned to Lessor along with MOD5 SOFTWARE.

                                      -8-
<PAGE>
 
6.   Confidentiality
     ---------------

     6.1  MOD5 SYSTEMS comprise unique, valuable, proprietary information.
Lessee agrees to maintain and protect Lessor's interests in proprietary
information and will accordingly keep all information pertaining to MOD5 SYSTEMS
in confidence and not use the same except as is necessary to the enjoyment and
exercise of the leases granted by Lessor hereunder at the PLANTS listed in the
attached Schedule 1. Lessee will take diligent action to fulfill the foregoing
obligations by instruction and agreement with its employees or agents respecting
the confidentiality of this information and shall obtain from them their written
commitments to comply with terms of confidentiality.

     6.2  Lessee shall adhere to the U.S. Export Administration Laws and
Regulations and shall not knowingly reexport, directly or indirectly, any MOD5M
SOFTWARE or MOD5 HARDWARE, or any technical data received from Lessor or the
direct products of such technical data in violation of 15 CFR Part 779 of the
U.S. Export Administration Regulations unless proper authorization of the U.S.
Government and the written consent of Lessor have previously been obtained.  No
law of conflicts or choice of law shall supersede this provision.

7.   Software Copies
     ---------------

     MOD5 SOFTWARE may only be copied, in whole or part, with property inclusion
of Lessor's copyright notice and any other proprietary notice required by
Lessor, as necessary and incidental to the use of such software for archival and
backup purposes or to replace a worn or defective copy. All such copies shall be
subject to the terms and conditions of this Agreement and shall be kept and used
at the designated PLANTS. If Lessee is unable to operate the MOD5 SOFTWARE on
originally

                                      -9-
<PAGE>
 
installed equipment, the MOD5 SOFTWARE may be transferred temporarily to another
system during the period of equipment malfunction.

8.   Warranties, Disclaimers and Validations
     ---------------------------------------

     8.1  THE EXPRESSED WARRANTIES HEREIN CONTAINED ARE IN LIEU OF ANY AND ALL
OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING THE WARRANTY OF MERCHANTABILITY
AND OF FITNESS FOR A PARTICULAR PURPOSE.  Lessor warrants that MOD5 SOFTWARE as
delivered will operate substantially as indicated in documentation provided by
the Lessor and will replace or provide instructions to adjust malfunctioning
components of MOD5 SOFTWARE on receiving notice thereof from Lessee.  Lessor
will expeditiously address the notice with, alternatively at Lessor's
discretion, replacement of the component with a currently available MOD5
SOFTWARE component or instructions for corrective logical modification of, or
other accommodative procedure for, the MOD5 SOFTWARE addressing the malfunction.
Lessee shall promptly, upon discovery, notify Lessor of any alleged deficiency
which may exist.

     8.2  Lessor warrants that the MOD5 SOFTWARE as delivered by Lessor under
this Agreement shall not infringe copyrights or patent rights of a third party
existing on the EFFECTIVE DATE.  Upon prompt written notice from Lessee
providing all pertinent details of a claim of such asserted infringement, Lessor
will undertake to investigate and at Lessor's expense to settle or to defend
against such a claim, provided Lessee grants any necessary authority and gives
its full support and cooperation, or to obtain the right for Lessee to continue
to use the MOD5 SOFTWARE, or to replace or modify the allegedly infringing
components of the MOD5 SOFTWARE which Lessor has so delivered to avoid any such
claim that is found to be valid. Without prejudice to the generality of the
foregoing, such expense shall extend to reasonable attorneys' fees incurred by
Lessee in


                                      -10-
<PAGE>
 
respect of such claim. If an award is rendered against Lessee, in any litigation
that the Lessor defends hereunder for infringement by the components of the MOD5
SOFTWARE which Lessor has so delivered, then Lessor shall reimburse Lessee for
damages and costs awarded by the judicial authority in respect to those
components.

     8.3  Lessee acknowledges that it is responsible for each APPLICATION
PROGRAM and is not relying on Lessor's skill or judgment to select or furnish
MOD5 SOFTWARE and associated MOD5 HARDWARE suitable for operation of a
particular manufacturing process and that there are no warranties which are not
contained in this Agreement.  Lessee acknowledges that it has made the selection
of the associated MOD5 HARDWARE. Lessor shall not be liable for special,
incidental or consequential damages arising out of or in connection with the
performance of systems utilizing MOD5 SOFTWARE and associated MOD5 HARDWARE.
Lessor shall not be responsible for any loss or damage caused by, nor shall any
payments due hereunder abate by reason of, any interruption in or loss of
service or use of the equipment or any part thereof arising from any reason not
solely attributable to Lessor. Without limiting the generality of the foregoing,
examples of the foregoing include errors in the APPLICATION PROGRAM, normal wear
and tear of the MOD5 SOFTWARE, or gradual deterioration of the MOD5 SOFTWARE.

     8.4  Lessor's total obligation after the EFFECTIVE DATE under this Article
shall in no event exceed one hundred percent (100%) of the total amount of the
payments actually received by Lessor under this Agreement.

     8.5  Whenever and to the extent validation of MOD5 SYSTEMS has occurred
under FDA regulations to date, Lessee shall retain those reports in support of
validation.  If revalidation of the process control system is necessary because
of extended 

                                      -11-
<PAGE>
 
requirements of the FDA regulations, Lessor shall provide information reasonably
required.

     8.6  With regard to any FDA validations in progress, or those to be
conducted in the future, Lessor shall provide information reasonably required
under FDA regulations with respect to MOD5 SYSTEMS validation.

9.   Liability, Indemnity and Risk of Loss
     -------------------------------------

     Lessee assumes all risks and liabilities, whether or not covered by
insurance, and shall indemnify and hold Lessor and its employees harmless for
any liability, claim, loss, damage or expense for injuries to or deaths of
persons and for damage to property, howsoever arising from or incident to the
possession, use, operation or storage of MOD5 SOFTWARE and associated MOD5
HARDWARE, and operation of the MOD5 SYSTEM, save and except for any matter
attributable to the sole negligence or willful misconduct of Lessor. Said
assumption of risks and liabilities by Lessee shall apply whether such injury or
death to persons be to agents or employees of Lessee or be to third persons and
whether such damage be to property of Lessee or to property of others.

10.  MOD5 SOFTWARE Maintenance and Support
     -------------------------------------

     10.1 Throughout the Term hereunder after installation of the MOD5 SOFTWARE,
Lessee shall maintain site conditions to provide an acceptable operating
environment for the MOD5 SOFTWARE as referenced in documentation provided by
Lessor.  Lessee is responsible for maintenance not provided under the Service
Agreement attached hereto as Appendix A and installation of the MOD5 SOFTWARE.
Lessee will maintain the MOD5 SOFTWARE in a current and up-to-date condition
adapting the APPLICATION PROGRAM to accommodate REMEDIAL PRODUCT NOTICES when
recommended by Lessor, which will be supplied by Lessor or by vendors 

                                      -12-
<PAGE>
 
approved by Lessor. Such adaptations will normally address operating
reliability. Lessor will counsel Lessee, as requested pursuant to the attached
Service Agreement, to accomplish the foregoing and Lessee shall permit Lessor or
Lessor's designee access to the MOD5 SOFTWARE for providing any necessary
assistance, such access to include network access if deemed appropriate.

     10.2 Lessor agrees to supply Maintenance and Support Services for MOD5
SOFTWARE, including maintenance and adjustment of associated MOD5 HARDWARE,
solely in accordance with the Service Agreement which is incorporated as
Appendix A of this Agreement. Lessor is not responsible for supply, maintenance
and adjustment of the MINICOMPUTER, and other commercially sourced computer(s)
or commercially sourced operating system(s) used in association with MOD5
SOFTWARE.

     10.3 Subject to Lessee's reasonable operating, safety and secrecy
requirements, Lessee shall grant Lessor PLANT access to the MINICOMPUTER and
other commercially sourced computer(s) used with MOD5 SOFTWARE during normal
working hours for inspection and installation of REMEDIAL PRODUCT NOTICES and
for any other reasonable purpose, such access to include network access if
deemed appropriate.  Lessee shall immediately notify Lessor of all details
concerning any malfunction arising out of the alleged or apparent improper
manufacture, functioning or operation of the MOD5 SOFTWARE.

11.  Notices
     -------

     Lessee and Lessor agree that notices required hereunder shall be deemed
received the seventh day after mailing, if mailed air postage prepaid to Lessor
or Lessee as the case may be at their respective address given below.

                                      -13-
<PAGE>
 
     If to Lessor, to:
                         Rofan Automation and Information
                              Systems B.V.
                         P.O. Box 48
                         4530 AA Terneuzen, The Netherlands
 
                         Attention: Hans Naninck, Director


     If to Lessee, to:   Biochimica del Salento S.p.A.
                         Via Murat 25
                         20159 Milan, Italy

                         Attention: _____________________________


Either party may change such address for notice by sending to the other party a
written notice.

12.  Severability
     ------------

     Any provision hereof prohibited by, or unlawful or unenforceable under, any
applicable law of any jurisdiction shall be ineffective as to such jurisdiction
without invalidating the remaining provisions of this Agreement.  In the event a
material provision is affected, the parties shall reformulate their mutual
undertakings in such manner as to preserve, as much as possible, their original
intentions and objects of this Agreement, consistent with the laws of such
jurisdiction.

13.  Alterations
     -----------

     Except for Lessee's remedial modification of APPLICATION PROGRAM, no
alterations to MOD5 SOFTWARE shall be made without first obtaining in each
instance the prior written approval of Lessor which approval shall be
expeditiously considered and not be unreasonably withheld.

                                      -14-
<PAGE>
 
14.  Conflicts and Assignability
     ---------------------------

     This Agreement does not operate as an acceptance of any conflicting terms
or conditions and shall prevail over any conflicting provision of any subsequent
purchase order or other instrument of Lessee, it being understood that any
purchase order or the request of Lessee acted upon by Lessor shall be for the
convenience of Lessee only but shall not operate to amend or modify in any
respect the terms hereof.  This Agreement may only be altered, modified,
supplemented or deviated from by further agreement in writing executed by an
authorized representative of each Lessor and Lessee.  Lessee and Lessor
acknowledge that by executing this Agreement each has reviewed the attachments
listed above and each agrees to be legally bound and dutifully perform its
obligations thereunder.  Lessor reserves the right to assign this Agreement to a
parent, affiliate or sister company of Lessor, but otherwise this Agreement
shall not be assignable by either party to a successor of the entire PLANT,
which undertakes all obligations assumed by Lessee hereunder by an agreement
executed and copied to Lessor and to whom Lessor has no reasonable objection.

15.  Applicable Law
     --------------

     The laws of the Kingdom of the Netherlands shall be applied in the
construction and interpretation of this Agreement.  No law of conflicts or
choice of law shall supersede this provision except as provided in Article 6.

                                      -15-
<PAGE>
 
     IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
on their behalf by their duly authorized representatives.

LESSOR:                             LESSEE:

ROFAN AUTOMATION AND
INFORMATION SYSTEMS B.V.            BIOCHIMICA DEL SALENTO S.p.A.


By: /s/ John C. Lillich             By: /s/  Helio Giglio          
   -----------------------             ---------------------------

Name:   John C. Lillich             Name:    Helio Giglio
     ---------------------               -------------------------

Title:  Attorney In Fact            Title:   Controller            
      --------------------                 -----------------------

Date:   May 3, 1995                 Date:    May 3rd, 1995
     ---------------------                ------------------------



By: /s/ Jane M. Gootee
   -----------------------

Name:   Jane M. Gootee
     ---------------------

Title:  Attorney In Fact
      --------------------

Date:   May 3, 1995
     ---------------------

                                      -16-
<PAGE>
 
                                  APPENDIX A
                                  ----------

                               SERVICE AGREEMENT

                                  MAINTENANCE



1.   Services
     --------

     (i) To facilitate efficient use of MOD5 SOFTWARE, Lessor agrees to provide
and Lessee agrees to acquire MOD5 SOFTWARE Maintenance Services as provided
hereunder.  Lessee has responsibility to acquire, through separate arrangements
with Lessor or another party, reasonable MOD5 HARDWARE training and/or services
necessary to apply DOWTRAN to the CONTROL SCHEMA and to remedially modify an
APPLICATION PROGRAM.

    (ii) Maintenance Services for MOD5 SOFTWARE include the notification of and
assistance for implementation, where necessary, of REMEDIAL PRODUCT NOTICES for
MOD5 SOFTWARE and remedial maintenance consultation for MOD5 SOFTWARE, MOD5
HARDWARE, FIRMWARE and other maintenance conducted by Lessee.  Repair of
subassemblies and printed circuit boards will be done by Lessor for Lessee's
account, i.e., at Lessee's expense, working with the vendor of such components.
Acquisition and installation of HARDWARE CONSUMABLES shall be the responsibility
of Lessee.

   (iii)  Lessor shall provide backup support for MOD5 SOFTWARE and MOD5
HARDWARE after Lessee has undertaken reasonable effort to resolve any MOD5-
related problem. Telephone support shall be provided within 24 hours of
notification of the problem and on-site service shall be provided within 48
hours of any such notification.

    (iv) Lessee shall be responsible for the appointment of one or more computer
systems professionals or process control professionals fluent in the English
language having a level of 

                                      -17-
<PAGE>
 
technical qualifications and experience acceptable to Lessor, whose acceptance
will not be unreasonably withheld, as manager for the MOD5 SOFTWARE. The MOD5
SOFTWARE manager shall enter into a secrecy agreement with Lessor to protect
Lessor's technology and shall cooperate with Lessor in enabling access to the
MOD5 SOFTWARE when appropriate.

     (v) "Special Services" reasonably required by Lessee at its PLANT sites any
time during the Term and upon termination of this lease, such as, for example,
services that may be required to assist Lessee in completing FDA validations of
process control in progress or for such technical support as may be reasonably
necessary in switching from MOD5 process control to another process control
system shall be provided by Lessor on reasonable notice for a period up to
twelve (12) workdays (8 hours per workday) over each successive twelve (12)
month period during the term of this lease measured from its EFFECTIVE DATE.
Special Service workdays not used within a given twelve (12) month period shall
not carry over to a subsequent period.

    (vi) Lessee and Lessor from time to time may agree on additional or new
Special Services beyond those agreed in this Agreement.  Any such additional or
new Special Services may be agreed to in a MOD5 Special Service Addendum. For
each separate request for services from Lessee, Lessor shall prepare and submit
to Lessee a written service proposal. The parties shall discuss the service
proposal and negotiate to agreement regarding the nature, scope, terms and
detail of the work. If agreement on the total scope is reached, the parties
shall develop a Special Service Addendum which shall define in detail the scope
of services and tasks to be performed, the schedule for completion and the
billing basis for such Special Services. Each MOD5 Special Service Addendum
shall be effective only if signed by an authorized representative of each party.
Each Special Service Addendum shall be sequentially numbered. A sample Special
Service Addendum is attached as Appendix B.

                                      -18-
<PAGE>
 
2.   Service Limitations
     -------------------

     Services are contingent upon the proper use of the MOD5 SOFTWARE and the
acquisition of associated MOD5 HARDWARE suitable for running MOD5 SOFTWARE.
Services do not include any of the following: electrical work external to the
INTERFACE PROCESSOR, MINICOMPUTER, or other commercially sourced computer(s) or
commercially sourced operating system(s) associated with the MOD5 SYSTEM;
replacing or providing HARDWARE CONSUMABLES: refinishing MOD5 SOFTWARE; or
maintenance of accessories, attachments, machines or other devices not provided
by Lessor.  Service shall not include practices which in Lessor's judgment are
unsafe or impractical for Lessor to render because of alterations to the MOD5
SOFTWARE or connection of the PLANTS by mechanical or electrical means to
machine devices furnished by a supplier other than Lessor. Service will not be
performed on MOD5 SOFTWARE located in an unsafe or hazardous environment, as
determined by Lessor. Service to be provided does not include service
necessitated by elements external to the MOD5 SOFTWARE which are not within
Lessor's operation or maintenance instructions or installation site preparation
guidelines including, but not limited to, humidity, temperature, power failure,
surges, air conditioning, grounding, static charge control, service resulting
from accident, neglect, alterations, improper use or misuse of the MOD5 SOFTWARE
or by repairs attempted by Lessee's personnel or service to a version other than
the installed version of MOD5 SOFTWARE and MOD5 HARDWARE.

3.   Service Charges
     ---------------
     (i) For Maintenance Services described in Article 1 performed at Lessee's
PLANTS, Lessee shall pay Lessor a service charge in the amount of Lessor's
standard charge for such 

                                      -19-
<PAGE>
 
services, plus reasonable travel and living expenses. This fee is presently U.S.
$125.00 per hour.

    (ii) For home based maintenance and support services described in Article 1
above conducted at the home locations of Lessor and its suppliers, Lessee shall
pay Lessor an annual fee as shown on Schedule 1 determined by multiplying the
total number of MOD CANS on which MOD5 SOFTWARE is run by a standard service fee
in U.S. Dollars.

   (iii)  Special Services pursuant to Article 1(v) shall be without charge for
up to 2 workdays in a single visit within each successive 12 month period during
the Term of this lease.  For additional workdays and additional visits within
each 12 month period Lessee shall pay Lessor a professional consulting fee of
U.S. $150.00 per hour for up to an additional 10 workdays.  Lessee shall
reimburse Lessor for reasonable travel and lodging expenses of such consultancy.

     (iv) Service charges accruing under this Article 3 will be invoiced and
shall be payable within thirty (30) days of receipt of an invoice therefor.
Payment for services shall be in U.S. Dollars.  In the case of expenses incurred
in another currency, such expenses shall first be translated by Lessor into U.S.
Dollars using the daily average rate quoted in Amsterdam by Bank Mendes Gans for
purchase of U.S. Dollars with the expense currency on the date of invoice, and
then invoiced in U.S. Dollars to Lessee.

                                      -20-
<PAGE>
 
                                  APPENDIX B
                                  ----------

                     MOD5 SPECIAL SERVICE ADDENDUM NO. ___
                     (Reference Article 1(vi) Appendix A)



(A)  Scope of Special Services:







(B)  Compensation:







(C)  Term or Schedule of Completion:
<PAGE>
 
(D)  Changes to Scope of Services:







(E)  Representatives:







(F)  Responsibility for Reporting:







(G)  Termination:

     This Special Service Addendum may be terminated (i) by either party with or
     without cause at any time upon 30 days written notice, or (ii) by the non-
     breaching party upon 2 days written notice in the event the other party
     fails to cure its breach of a material obligation under the Agreement or
     this Special Service Addendum within 20 days of its receipt of a notice
     alleging such breach from the other party.
<PAGE>
 
     Upon termination of the Special Service Addendum, Lessor shall invoice
     Lessee for all services performed by Lessor under this Special Service
     Addendum prior to the termination for which Lessor was not previously
     compensated, and for expenses necessary to shut down the project.


ACCEPTED AND AGREED, as of the later of the two dates noted in the signature
blocks, by each Party's authorized representative.


Lessor:                             Lessee:

ROFAN AUTOMATION AND
INFORMATION SYSTEMS B.V.            BIOCHIMICA DEL SALENTO S.p.A.



By:                                 By: 
    --------------------------          --------------------------

Name:                               Name:                          
      ------------------------            ------------------------


Title:                              Title:                        
       -----------------------             -----------------------


Date:                               Date:                           
      ------------------------            ------------------------
<PAGE>
 
                                  SCHEDULE I
                                  ----------

                             LEASED MOD5 SOFTWARE
                             --------------------
<TABLE>
<CAPTION>
                             NUMBER OF         LEASE               ANNUAL
SITE           PLANT         MOD CANS         CHARGES           SUPPORT FEES
- ----           -----         ---------       ---------          ------------
<S>            <C>           <C>            <C>                <C>
  
BRINDISI,      BIOCHIMICA        9              NONE            U.S.$11,700.00
ITALY          DEL SALENTO                  (ANTEDATES LEASING)
               PROCESS
 
 
MOD5 SYSTEMS DESCRIPTION:
- -------------------------
 
 NUMBER OF SYSTEMS:      2
 
 VERSIONS:
  CPU:                   MOD5+
  OVERHEAD SOFTWARE:     REL. 0643
  GPI:                   REL. V 2.00
  DSS:                   REL. V 2.00
  MODSERVER
   HARDWARE:             AS STADE STANDARD
   SOFTWARE:             REL. V 2.0e


BRINDISI,      BIOCHIMICA        1              NONE            U.S.$ 1,300.00
ITALY          DEL SALENTO                  (ANTEDATES LEASING)
               SIMULATION/
               MAINTENANCE
 
MOD5 SYSTEMS DESCRIPTION:
- -------------------------
 
 NUMBER OF SYSTEMS:      1
 
 VERSIONS:
  CPU:                   MOD5+
  OVERHEAD SOFTWARE:     REL. 0643
  GPI:                   REL. V 2.00
  DSS:                   REL. V 2.00
  MODSERVER
   HARDWARE:             AS STADE STANDARD
   SOFTWARE:             REL. V 2.0e



                   TOTAL ANNUAL SUPPORT FEES:                   U.S.$13,000.00
</TABLE> 



                                  PAGE 1 OF 1
<PAGE>
 
                      PERSONAL CONFIDENTIALITY AGREEMENT
                      ----------------------------------


DECLARATIONS:


     The undersigned employee of BIOCHIMICA DEL SALENTO S.p.A. (Biochimica) has
certain responsibilities for maintaining and operating MOD5 SYSTEMS for
manufacturing process control.

     The undersigned Affiliate of The Dow Chemical Company (Dow) is willing to
continue supporting MOD5 SYSTEMS used by Biochimica according to the terms of
the "Computerized Process Control Software Agreement" entered into between
Affiliate and Biochimica with the proviso that the latter appoint a MOD5
SOFTWARE technical manager with appropriate competencies in the English language
and pertinent technical qualifications:


ASSURANCES:


     The undersigned acknowledges he/she has been assigned such responsibilities
regarding MOD5 SYSTEMS by Biochimica and affirms:

     1.   That he/she is familiar with the "Computerized Process Control
Software Agreement" mentioned above, including those terms thereof regarding
confidentiality of information.

     2.   That pursuant to the terms of the Agreement he/she will not disclose
to others proprietary information about MOD5 SYSTEMS nor make any unauthorized
copies of documents containing such information, and moreover agrees that no
personal rights to use any information acquired in working with MOD5 SYSTEMS are
expressly or impliedly acquired hereunder.

     It is understood by the undersigned and Affiliate of Dow that these
obligations shall not apply to information which is or becomes part of the
public domain through no fault of the undersigned or is received by the
undersigned on a nonconfidential basis from a third party who is not under an
obligation of confidence to Dow or a Dow Affiliate.

ACCEPTED BY                           ROFAN AUTOMATION AND
BIOCHIMICA Representative:            INFORMATION SYSTEMS B.V


                                       By:
- -----------------------------              --------------------------

Name:                                  Name: 
      -----------------------                ------------------------

Title:                                 Title: 
       ----------------------                 -----------------------

Date:                                  Date: 
      -----------------------                ------------------------

<PAGE>
  
                        INSURANCE SEPARATION AGREEMENT
                        ------------------------------


          This AGREEMENT, dated as of the 3rd day of May, 1995, is made by and
among The Dow Chemical Company ("Dow"), Hoechst Corporation ("Hoechst"), Marion
Merrell Dow Inc. ("MMD") and Dow's three wholly-owned insurance subsidiaries --
Dorinco Reinsurance Company ("Dorinco"), Dorintal Reinsurance Ltd. and Timber
Insurance Ltd. (collectively, the "Dow Insurance Subsidiaries") -- hereinafter
referred to collectively as "the Parties," and shall be binding upon the
successors and assigns of each.

          WHEREAS, Dow has, for many years, used the combined purchasing power
of itself and its subsidiaries to purchase insurance to protect Dow and its
subsidiaries against the risk of certain losses by reason of legal liability in
the U.S. and elsewhere, thus enabling Dow and its subsidiaries to obtain for
themselves enhanced levels of coverage in return for their premium dollars;

          WHEREAS, the aforementioned policies of insurance purchased by Dow
provide coverage to, inter alia, the Named Insured, which is defined to include
not only Dow but also any domestic or foreign corporation (not specifically
excluded) in which Dow owns, or may acquire, directly or indirectly, more than
50% of the combined voting power (later revised to 60% or more of the combined
voting power);

<PAGE>
 
          WHEREAS, Dow's subsidiaries have shared in the purchase costs of the
aforementioned policies by paying to Dow an allocated share of the total premium
based in part on the subsidiaries' respective levels of loss activity;

          WHEREAS, Dow acquired a majority voting interest in the shares of
Merrell Dow Pharmaceuticals, Inc. ("MDPI") on or about March 10, 1981, and MDPI
thereby became a Named Insured under all Dow liability insurance policies
effective on or after that date;

          WHEREAS, Dow and its wholly-owned holding companies acquired a
majority voting interest in the shares of MMD on or about December 2, 1989, and
MMD thereby became a Named Insured under all Dow liability insurance policies
effective on or after that date;

          WHEREAS, as part of the transaction in which Dow acquired a majority
interest in MMD, the shares of MDPI were transferred to MMD;

          WHEREAS, some of the insurance policies purchased by Dow contain
aggregate limits of liability which are reinstated by payment of an additional
premium by the Named Insured;

          WHEREAS, some of the insurance policies purchased by Dow contain a
premium feature which is partially retrospective and loss-responsive in nature;
i.e., the amount of the premium is determined, in part, by the amounts paid by
the insurer, plus applicable reserves established by the insurer;

                                       2
<PAGE>
 
          WHEREAS, some of the insurance policies purchased by Dow contain a
deductible obligation or a self-insured retention, whereby the Named Insured
must pay certain amounts;

          WHEREAS, the costs of purchasing various types of insurance from
various companies may be affected by loss experience in a variety of ways;

          WHEREAS, Hoechst has entered into an agreement to acquire Dow's stock
in MMD and Roussel Uclaf S.A. has entered into an agreement to acquire certain
Latin American pharmaceutical businesses of various Dow subsidiaries;

          WHEREAS, Hoechst has insurance subsidiaries named Hoechst Celanese
Insurance Company and Elwood Insurance Limited and Hoechst A.G. has an insurance
subsidiary named Hoechst Versicherungs A.G. (collectively, the "Hoechst
Insurance Subsidiaries");

          WHEREAS, the Parties have divergent views and interests which they
wish to resolve by the agreements set forth below concerning their respective
obligations to make certain payments and bear certain costs, including but not
limited to reinstatement premiums, retrospective premiums, deductibles and
retentions, in the event claims are made or suits are brought against MMD and/or
its subsidiaries which are or may be covered by various insurance policies
purchased by Dow;

                                       3
<PAGE>
 
          WHEREAS, the Parties further desire to accomplish a partial separation
of their insurance interests and to attain a degree of certainty about their
respective rights and obligations with respect to insurance coverage and their
rights and obligations in the event that existing insurance is insufficient to
cover certain claims against them.

          NOW, THEREFORE, the Parties hereby agree as follows:

          1.  MMD shall designate its new insurance subsidiary ("New Sub") or
one of the Hoechst Insurance Subsidiaries (with the subsidiary selected being
referred to herein as "Newco"), which will reinsure the Dow Insurance
Subsidiaries with respect to all claims made or suits brought against MMD and/or
its subsidiaries which are insured or reinsured, directly or indirectly, by the
Dow Insurance Subsidiaries under policies identified in Appendix A hereto.  The
contract of reinsurance to be issued by Newco (the "Newco Reinsurance Contract")
will be in a form commonly accepted in the domestic reinsurance industry,
written in such manner as to allow the Dow Insurance Subsidiaries to take
"reinsurance credit" on their statutory reports.  The Newco Reinsurance Contract
will be effective January 1, 1995.  Newco shall not be liable under the Newco
Reinsurance Contract for any sums paid by the Dow Insurance Subsidiaries in
respect of any of the claims identified in Appendix B hereto [DOW To Review],

                                       4
<PAGE>
 
nor for any sums paid by Dorinco prior to January 1, 1995 in respect of claims
submitted by MMD prior to January 1, 1995.

          2.  The amount to be paid to Newco by the Dow Insurance Subsidiaries
as a premium for the reinsurance required by paragraph 1 is $45,000,000 payable
after the execution of the Newco Reinsurance Contract and the later of the date
Hoechst purchases Dow's stock in MMD as contemplated by the Stock Purchase
Agreement referred to in Paragraph 7(a) hereof (the "Effective Date") or, if
Newco is New Sub, three business days after notice to the Dow Insurance
Subsidiaries of receipt by Newco of its Certificate of Authority.

          3.  This Paragraph 3 shall apply only if New Sub is designated to be
Newco.  Commencing upon receipt by New Sub of its Certificate of Authority,
Dorinco agrees to assist New Sub, at New Sub's election, by retroceding to New
Sub certain third party reinsurance.  Prior to the year-end renewal period, and
at other times as may be appropriate, Dorinco and New Sub shall meet and New Sub
shall be given the opportunity to review the proposed Dorinco third party book
of business.  New Sub shall indicate to Dorinco at that time the Dorinco lines
of third party business, if any, in which it seeks to participate by quota share
retrocession and the specific amount of ceded premiums it wishes to accept on
each line of third party business; provided, however, that in no event shall
Dorinco be required to cede more than $25,000,000 in premium on all lines
 
                                       5
<PAGE>
 
of business in the aggregate to New Sub.  New Sub shall also provide Dorinco
such other information as Dorinco may reasonably require to determine the nature
and extent of New Sub's desired level of quota share participation by
retrocession in the specified lines of third party business.  Dorinco may write
additional reinsurance on the lines of business designated by New Sub and will
exercise its reasonable best efforts to cede to New Sub the levels of  premiums
indicated by New Sub on the lines of third party business designated by New Sub,
with New Sub assuming its quota share of premiums, losses and expenses with
respect to the reinsurance of the selected lines.  Such contracts of reinsurance
between Dorinco and New Sub will be in a form commonly accepted in the domestic
reinsurance industry, written in such manner as to allow Dorinco to take
"reinsurance credit" on its statutory reports.  In return for the retrocessions
provided by Dorinco, New Sub shall pay to Dorinco a ceding commission equal to
one percent of the insurance premiums retroceded to New Sub by Dorinco.  Dorinco
agrees to provide New Sub with the assistance referenced in this Paragraph 3 for
an initial period of three years commencing from New Sub's receipt of its
Certificate of Authority, extendable for an additional two years upon mutual
agreement of Dorinco and New Sub.  New Sub shall have the right to cancel all or
any part of any retrocession from Dorinco, effective at the conclusion of any
calendar year,
 
                                       6
<PAGE>
 
provided notice of intent to cancel is received by Dorinco at least six
months in advance.

          4.  (a)  MMD shall reimburse and indemnify Dow for any and all
reinstatement premiums, retrospective premiums, deductibles, retentions, and any
other costs incurred and paid by Dow to its insurers under any insurance or
reinsurance policy issued to Dow prior to the Effective Date (including policies
issued by Dow Insurance Subsidiaries), which result from claims made by MMD
and/or its subsidiaries; provided, however, that MMD shall not be required to
reimburse or indemnify Dow pursuant to this Paragraph 4 for any amount which
will otherwise be paid to Dow or its subsidiaries by Newco pursuant to the Newco
Reinsurance Contract or for costs that Dow must pay under Paragraphs 6 through 9
below.

          (b)  In the event that MMD or one of its subsidiaries elects to report
a claim or circumstance under the 1994-1995 ACE Insurance Company, Ltd. ("ACE")
insurance policy bearing policy number DOW 5115/4 ("the 1994-1995 ACE Policy"),
with respect to claims by MMD or one of its subsidiaries, then MMD agrees to
make all Loss Recoverable Payments, as defined in the 1994-1995 ACE Policy,
which result from amounts paid by ACE to MMD or one of its subsidiaries.  Except
as set forth elsewhere in subparagraphs 4(a) and (b), any other premium
adjustments on insurance policies purchased or renewed by Dow on or after the
Effective Date shall be the sole responsibility of Dow and will not be
chargeable to MMD or one of its subsidiaries.
 
                                       7
<PAGE>
 
          5.  Dow shall provide MMD with quarterly reports indicating any
amounts paid by Dow and due from MMD pursuant to Paragraph 4.  MMD shall pay Dow
any undisputed amount specified in any such report within 30 days of MMD's
receipt of any such report.  MMD shall, upon reasonable notice to Dow, have the
right to audit documentation, including relevant invoices and checks, supporting
such reports.  Any disputes under Paragraph 4 will be subject to binding
arbitration.

          6.  One of the Dow Insurance Subsidiaries (that Dow Insurance
Subsidiary is referred to hereafter as the "Dow Insurance Subsidiary") will
issue an insurance policy in form and substance reasonably satisfactory to
Hoechst, Dow and the Dow Insurance Subsidiary, which policy shall include the
terms and conditions described below, and shall indemnify the Covered Entities
(as defined below) against Losses (as defined below) incurred and paid by the
Covered Entities in excess of an aggregate of $150 million of Losses arising
from Claims (as defined below) against Covered Entities now-pending or asserted
during the fifteen years subsequent to the Effective Date resulting from or
relating to an anti-nauseant drug sold under trademarks Bendectin, Debendox,
Lenotan,  Merbental and Dectamin ("the Bendectin Policy").  It is agreed that
any expenditures by MMD before the date of this Agreement made on account of
Claims resulting from or related to Bendectin shall not be "Losses" unless they
are 
 
                                       8
<PAGE>
 
included on Schedule 6(a). Such expenditures on Schedule 6(a) shall be Losses 
only to the extent that such expenditures are verified by Dow and not paid by 
insurance.

          7.  The Bendectin Policy shall include the following terms and
conditions:

               (a)  "Covered Entities" shall include (i) Hoechst A.G. and its
     subsidiaries and affiliates to the extent that they own directly or
     indirectly any of the entities or businesses acquired by Hoechst in its
     acquisition of MMD pursuant to the Agreement and Plan of Merger, dated as
     of May 3, 1995, by and among Hoechst, H Pharma Acquisition Corp.
     ("Acquisition"), Dow and MMD and the Stock Purchase Agreement, dated as of
     May 3, 1995, by and among Hoechst, Acquisition, Dow and certain
     subsidiaries of Dow (the "Stock Purchase Agreement"); (ii) Roussel Uclaf
     S.A. ("Roussel Uclaf") and its affiliates and subsidiaries to the extent
     that they own directly or indirectly any of the entities or businesses
     acquired directly or indirectly by Roussel Uclaf pursuant to the Purchase
     Agreement, dated May 3, 1995 among Latin American Pharmaceutical Inc., Dow
     Quimica Argentina S.A., Dow Quimica Mexicana S.A., Dow Productos Quimicos
     LTDA, Mineracao e Quimica de Nordeste, Dow Quimica S.A., Merrell Lepetit
     Farmaceutica Industrial LTDA, Laboratorios Lepetit de Mexico S.A. de C.V.
     and Roussel Uclaf (the     

                                       9
<PAGE>
 
     "LAPG Purchase Agreement"); (iii) MMD and all of its present and former
     subsidiaries; and (iv) all successors and assigns of the entities referred
     to in clauses (i), (ii) and (iii) above; provided, however, that their
     Claims under the Bendectin Policy must relate to the products sold prior to
     the Effective Date under the trademarks Bendectin, Debendox, Lenotan,
     Merbental and Dectamin (collectively "Bendectin").

               (b)  The Bendectin Policy will be subject to an aggregate limit
     of liability of $250 million so that the Dow Insurance Subsidiary that
     issues the Bendectin Policy will have no obligation under the Bendectin
     Policy to pay more than $250 million.  This limit of liability shall not be
     reduced by any costs or expenses of the Dow Insurance Subsidiaries in
     administration of claims under the Bendectin Policy or by salaries or other
     expenses of employees of Dow or the Dow Insurance Subsidiaries.

               (c)  The Bendectin Policy will be subject to a per occurrence
     limit of $250 million.

               (d)  "Claims" shall include only those claims made by specific
     individuals (including, without limitation, class actions) arising from or
     derived from use of a product (including, without limitation, claims of
     loss of consortium or inherited disease or birth or other defect or
     increased risk of disease or birth or other defect inherited, directly or
     indirectly from
 
                                       10
<PAGE>
 
     a user of such product).  Subject to the limitations in
     the immediately preceding sentence, "Claims" shall include those alleging,
     without limitation, bodily injury, mental and emotional injury (including
     fear of cancer or other disease or defect and increased risk of cancer or
     other disease or defect), as well as claims seeking medical monitoring.

               (e)  "Loss" or "Losses" shall include all out-of-pocket payments
     with respect to settlements, compensatory, statutory and punitive damages,
     and hospital and medical expenses, as well as fees, costs and expenses of
     the investigation, adjustment, defense and appeal of any Claim.  "Losses"
     shall not include costs or expenses of Covered Entities in administration
     of Claims or salaries of employees of the Covered Entities.

               (f)  Subject to subparagraph 7(j) below, beginning on the
     Effective Date and on each of the fourteen subsequent anniversaries of the
     Effective Date, MMD shall pay to the Dow Insurance Subsidiary that issued
     the Bendectin Policy an annual premium of $100,000.

               (g)  Subject to the remainder of this subparagraph, the Covered
     Entities have the sole right to control the defense of all Claims.
     Before the $150 million retention under the Bendectin Policy is exhausted,
     MMD will give notice to and consult with Dow and the Dow Insurance
     Subsidiary concerning settle-

                                       11
<PAGE>
 
     ments of Claims arising from or related to Bendectin in excess of $5
     million. The Covered Entities will not settle any Claims arising from or
     related to Bendectin after the $150 million retention under the Bendectin
     Policy is exhausted without the consent of Dow Insurance Subsidiary, which
     will not be unreasonably withheld. In the event that the Covered Entity and
     the Dow Insurance Subsidiary cannot agree on an appropriate settlement of
     the Claim, the matter shall be submitted to binding arbitration before a
     practitioner experienced in product liability defense or a retired judge,
     in either case mutually agreeable to the Dow Insurance Subsidiary and the
     Covered Entity. In the event the Dow Insurance Subsidiary and the Covered
     Entity cannot agree upon the selection of an arbitrator, the Dow Insurance
     Subsidiary and the Covered Entity shall jointly ask JAMS/Endispute, or its
     successor, to select a qualified arbitrator. The decision of the arbitrator
     as to the action to be taken shall be final and binding on both the Dow
     Insurance Subsidiary and the Covered Entity.

               (h)  The term "Loss" shall not include any  payment by the
     Covered Entities that is actually reimbursed by any third party insurer
     (net of charge backs to the Covered Entities of any kind, which charge
     backs shall include, without limitation, reinstatement premiums,
     retrospective premiums, deductibles, retentions, any payments by MMD or its
     subsidiaries under paragraph 4 above and any other costs incurred to obtain
     payment under any insurance policy) pursuant to insurance in existence on
     the

                                       12
<PAGE>
 
     Effective Date (other than the Bendectin Policy or insurance that is ceded
     by the Dow Insurance Subsidiaries to Newco under the Newco Reinsurance
     Contract).  The Dow Insurance Subsidiary shall have the right to decline to
     allow a deduction from insurance recoveries for the costs of further
     prosecution by the Covered Entities of an insurance coverage action which
     the Dow Insurance Subsidiary deems to be unreasonable; provided, however,
     that this sentence applies only to the extent that the fees and costs of
     such insurance coverage action exceed the Covered Entity's recovery.  The
     Bendectin Policy shall be null and void with respect to a particular Loss
     to the extent that such Loss is covered and paid (after giving effect to
     all applicable charge backs of the types described above) by any insurance
     other than the Bendectin Policy and insurance ceded by Dow or its
     subsidiaries to Newco under the Newco Reinsurance Contract.

               (i)  A Claim relating to conduct of a business or entity acquired
     by any of the Covered Entities after the Effective Date, except to the
     extent that such business or entity is or becomes a successor or assign of
     the liabilities of any of the Covered Entities, shall not give rise to a
     Loss under this Agreement or the Bendectin Policy.  In connection with any
     sale or transfer of all or part of any of the Covered Entities, the Covered
 
                                       13
<PAGE>
 
     Entities in their sole discretion, may assign, in whole or in part, the
     rights to, along with related obligations under, the Bendectin Policy to 
     such buyer or transferee.

               (j)  Hoechst shall have the right to cancel the Bendectin Policy
     at any time, in which case the Dow Insurance Subsidiary that issued the
     Bendectin Policy shall refund to Hoechst the pro rata portion of the
     $100,000 annual premium allocated to the remainder of the policy year, and
     the issuer of the Bendectin Policy shall have no further liability or
     obligation to make any future payment of any kind under the Bendectin
     Policy, except with respect to Claims asserted against the Covered Entities
     and noticed to the Dow Insurance Subsidiary on or before the date of
     cancellation.

               (k)  The determination of which Dow Insurance Subsidiary shall
     issue the Bendectin Policy required by Paragraphs 6 and 7 shall be
     made by Dow and the Dow Insurance Subsidiaries solely in their discretion,
     and Dow shall guaranty the payment obligations of the Dow Insurance
     Subsidiary that issues the Bendectin Policy.  If, and only if, the full
     $250 million in coverage available under the Bendectin Policy has been paid
     so that the $250 million aggregate limit of that policy is exhausted, Dow
     agrees that it then will reimburse the Covered Entities for 50% of any
     additional payments made by the Covered Entities for Losses arising from
     Claims against Covered Entities 
 
                                       14
<PAGE>
 
     resulting from or related to Bendectin which are now-pending or asserted
     within the 15-year period ending on the fifteenth anniversary of the
     Effective Date.

          8.   Gruppo Lepetit, S.p.A. (with its present and former subsidiaries,
and all of their successors and assigns, referred to herein as "Lepetit") is a
subsidiary of MMD.  While Dow does not believe that Lepetit has any material
exposure to Claims (as defined in Paragraph 7(d)) resulting from its sale or
distribution of breast implants, in order to facilitate the sale of MMD and its
subsidiaries to Hoechst and the closing of the LAPG Purchase Agreement, Dow will
pay to Hoechst or its designee, subject to the limitations set forth below, $55
millon on the Effective Date, which may be used by Hoechst for any purpose.  In
connection with this payment, Hoechst shall establish an account for record-
keeping purposes only with the following characteristics:

               (a)  For record of account purposes, the initial amount of the
     account shall be $55 million.

               (b)  For record of account purposes, the account, as adjusted
     from time to time pursuant to subparagraph (c) below, shall bear interest
     compounded annually at an interest rate equal to the average yield-to-
     maturity of a U.S. treasury bond with 20 years remaining to maturity in
     effect as of the fifth business day prior to the Effective Date.
 
                                       15
<PAGE>
 
               (c)  For record of account purposes, if and when Lepetit has made
     payments for Losses arising from Claims that result from or relate to
     breast implants and that arise from activities of Lepetit prior to the
     Effective Date ("Breast Implant Claims"), the account shall be reduced by
     the amount of such payments.  An expenditure will not be a payment for
     purposes of the preceding sentence to the extent Lepetit is reimbursed by
     any third party insurance or pursuant to Paragraph 9 hereof (other than
     insurance ceded by the Dow Insurance Subsidiaries to Newco under the Newco
     Reinsurance Contract) in existence on the Effective Date (it being agreed
     that any such reimbursement shall be reduced by the amount of all
     applicable charge backs of the types referred to in paragraph 7(h) above).
     There shall be no other deductions from the account.

Hoechst shall on a yearly basis, beginning one year from the Effective Date,
give Dow a statement of this account.  Dow shall have the right to audit the
account on a yearly basis.  On the first business day following the twentieth
anniversary of the Effective Date, Hoechst shall pay Dow an amount equal to any
balance in the account net of reserves established by an actuarial estimate
performed by a mutually agreed-upon independent actuary with respect to each
then-pending Claim.  
 
                                       16
<PAGE>
 
Upon final resolution of any Claim for which a reserve has been established, an
amount equal to the remaining reserve, if any, after payment of all Losses
applicable to such Claim, shall be paid to Dow. When all such reserved Claims
have been finally resolved, an amount equal to the remaining reserve, if any,
shall be paid to Dow immediately. In the event that the total reserve
established at the end of 20 years proves insufficient to cover the total Losses
for the open Claims reserved at the end of 20 years, Dow shall be obligated to
pay to Hoechst an amount equal to the deficiency of the reserve but in no case
more than the amount that was refunded to Dow as provided above after the
expiration of the twenty year period. In the event that Hoechst receives a
recovery from an insurer with respect to a Loss or portion of a Loss which was
previously charged against the record account, the amount of such recovery (but
not to exceed the portion of the Loss previously charged against the account)
shall be paid to Dow by Hoechst.

          9.  Dow has in effect a $50 million excess insurance policy (Policy
No. XLUMB-00167) issued by XL Insurance Company, Ltd. ("XL") for the policy year
1993-1994 ("the 1993-1994 XL Policy").  Lepetit and MMD are  insured under the
1993-1994 XL Policy, and Dow, various Dow subsidiaries other than Lepetit and
MMD, and Lepetit and MMD each believe that they are entitled to coverage under
the 1993-1994 XL Policy.  Dow shall pay any charges required to extend the
period for Lepetit to report claims resulting from or related to Breast Implant
Claims under the 1993-1994 XL Policy.  In the event that Dow or any of its
subsidiaries or affiliates receives any payment from XL that reduces limits
available to Lepetit (and only Lepetit) under the 1993-1994 XL Policy (or any
successor thereto), Dow shall obtain and maintain, at its own expense, insurance
from XL, one of the Dow Insurance Subsidiaries or any other insurance company
under which the insurer shall agree to pay to Lepetit any amount which would
have been payable under the 1993-1994 XL Policy (or the applicable successor
policy) but for the fact that some portion of the $50 million limits available
under that policy (or the applicable successor policy) was depleted by payments
by XL (or the successor insurer) to Dow or one of its subsidiaries other than
Lepetit.  Notwithstanding anything provided herein, Dow will take all actions
and pay all expenses neces-
 
                                       17
<PAGE>
 
sary to preserve the XL Policy for Lepetit or, at its sole option, Dow may
obtain from one of the Dow Insurance Subsidiaries or any other insurer, and
maintain, at its own expense, an insurance policy providing Lepetit with the
same benefits, on the same terms and conditions, as the 1993-1994 XL Policy with
policy limits reduced from $50 million to reflect any amounts already paid to
Lepetit under the 1993-1994 XL Policy. Dow shall guaranty the payment of any
insurer under any policy obtained by Dow to satisfy its obligations under this
Paragraph 9, including the obligations of XL under the 1993-1994 XL Policy.
Because Dow's obligation under this Paragraph 9 shall be to provide Lepetit
(through the 1993-1994 XL Policy or otherwise) a full $50 million of coverage,
which shall not be reduced except by payments to Lepetit, any payment to XL or
any successor to XL that is necessary under the 1993-1994 XL Policy (or any
successor policy) to achieve access to the full $50 million of coverage (less
payments to Lepetit), including, without limitation, reinstatement or
retrospective premiums, will be made by Dow. Dow's obligations under this
Paragraph 9 shall continue until all Claims asserted on or before twenty years
from the Effective Date have been disposed of or otherwise satisfied. For
purposes of paragraphs 8 and 9, Lepetit shall include Gruppo Lepetit, S.p.A. and
all of its present or former subsidiaries and all of their respective successors
and assigns. In connection with any sale or transfer of all or part of Lepetit,
Lepetit may, in its sole discretion, assign, in

                                       18

<PAGE>
 
whole or in part, the rights to, along with related obligations under, this
Paragraph 9 to such buyer or transferee.

          10.  Additional details concerning the agreed-upon effects of this
Agreement and the sale of MMD and its subsidiaries upon certain insurance
policies covering MMD and its subsidiaries are set forth in Appendix C.  To the
extent there is any conflict between Appendix C and this Agreement, this
Agreement shall govern.  The Parties agree that Dow shall relinquish any rights
it has under insurance policies issued to the entities or businesses acquired by
Hoechst under the Stock Purchase Agreement but only with respect to time periods
such policies were in effect prior to the time such entities or businesses were
acquired by Dow, including without limitation, such pre-acquisition insurance
policies issued to Richardson-Merrell Inc., Marion Labs Inc., The Rugby Group,
Inc. and Gruppo Lepetit, S.p.A. and their predecessors.

          11.  This Agreement does not affect the Covered Entities' rights to
coverage under any insurance or reinsurance policy purchased by Dow which
formerly provided or currently provides coverage to the Covered Entities.  With
respect to such policies issued by the Dow Insurance Subsidiaries, the Dow
Insurance Subsidiaries agree that they will continue the practices established
in the past with respect to such policies.  Dow will use reasonable best efforts
to assist the Covered Entities in presenting and collecting claims under
policies issued to Dow by third party insurers.  Within 90 days of the execution
of this 
 
                                       19
<PAGE>
 
Agreement, Dow will provide to Hoechst copies of all Dow insurance policies
which formerly provided or currently provide coverage to any of the Covered
Entities. Dow shall on a yearly basis give Hoechst a statement indicating the
status of exhaustion of all such policies and Hoechst shall have the right to
audit upon reasonable notice to Dow.

          12.  Hoechst, MMD and their subsidiaries will exercise their
reasonable best efforts to recover any insurance which will inure, directly or
indirectly, to the benefit of Dow or its subsidiaries, including without
limitation the Dow Insurance Subsidiaries, under this Agreement.  This Paragraph
shall not be interpreted to require the Covered Entities to file or prosecute
any legal proceedings against their insurers.  In the event that a Covered
Entity elects not to prosecute a lawsuit for such insurance recoveries and Dow
elects to pursue such an action, the following rules shall apply concerning
recoveries obtained by Dow:

               (a)  With respect to recoveries arising from Losses resulting
     from or related to Bendectin:

                     (1)  to the extent that the $150 Million retention under
               the Bendectin Policy is not yet exhausted, the Covered Entity
               will receive the recovery, net of the fees and expenses paid by
               Dow in pursuing the coverage action and the Covered Entities'
               $150 Million retention under the Bendectin Policy will be
               increased by the same amount;

                                       20
<PAGE>
 
                     (2)  to the extent that the $150 Million retention under
               the Bendectin Policy is exhausted and the Dow Insurance
               Subsidiary has paid the Covered Entity the underlying Loss, the
               Dow Insurance Subsidiary will receive the recovery and the Dow
               Insurance Subsidiary will be responsible for all fees and
               expenses of pursuing the coverage action; and

                     (3)  to the extent that the $250 Million limit of the
               Bendectin Policy is exhausted and Dow has paid the Covered Entity
               50 percent of the underlying Loss, the Covered Entity will
               receive 50 percent of the recovery, net of 50 percent of the fees
               and expenses of pursuing the coverage action, and Dow will keep
               the remainder of the recovery.

               (b)  With respect to recoveries arising from Losses resulting
     from or related to Breast Implant Claims:

                     (1)  to the extent there is still a positive balance in the
               record of account referred to in Paragraph 8: (i) Dow will
               receive the recovery, (ii) Dow will be responsible for all fees
               and expenses of pursuing the coverage action, and (iii) the
               record of account referred to in Paragraph 8 will not be affected
               by such recovery; and

                     (2)  to the extent there is no remaining positive balance
               in the record of account referred to in Paragraph 8, Dow shall
               have no rights to pursue the Covered Entities' claims against
               their insurers.

                                       21
<PAGE>
 
          13.  The Covered Entities shall have discretion concerning the
reasonableness of any settlements with their third party insurers, which shall
be deemed reasonable absent a showing of bad faith, except as provided elsewhere
herein.   With respect to Breast Implant Claims only, when a Covered Entity
reaches a written letter of intent or agreement in principle to settle with any
of its third party insurers and at the time of the settlement there is still a
positive balance in the record of account referred to in paragraph 8, the
Covered Entity shall give Dow notice of such letter of intent or agreement in
principle and 20-days within which to approve the settlement or take assignment
of the claim against such insurer.  If Dow elects to take assignment of the
claim against such insurer, Dow must, as a condition of such assignment, pay the
Covered Entity the full amount to be paid to the Covered Entity under the
proposed letter of intent or agreement in principle.  The balance in the record
of account established under paragraph 8 hereto shall be increased by the amount
of such payment by Dow to the Covered Entity.  Dow will be entitled to retain
any recoveries it receives from its prosecution of such claim against such
insurer.  When there is no remaining positive balance left in the record of
account described in paragraph 8 and no outstanding insurance recoverables, Dow
will have no rights concerning settlements proposed by the Covered Entities.
 
                                       22
<PAGE>
 
          14.  This Agreement is a commercial resolution of negotiations
concerning the separation of complex insurance and risk management programs of
MMD, Lepetit and Dow and its other subsidiaries.  Dow does not believe that any
party to this Agreement, including Lepetit, has any legitimate financial
exposure due to sale or distribution of breast implants, and nothing in this
Agreement should be viewed as an admission by Dow of any kind.  This Agreement
represents a compromise of disputed claims and shall not be construed as an
admission by any party as to the correct interpretation or application of any
insurance policies purchased by Dow.

          15.  This Agreement may be executed in counterparts.

          16.  The parties shall not be obligated to perform their obligations
under this Agreement until the Effective Date.  This Agreement shall terminate
upon any termination of the Stock Purchase Agreement referred to in paragraph
7(a) hereof.

          17.  In connection with entering into this Agreement, Dow represents
and warrants to Hoechst that, on the basis of work performed by and on behalf of
Dow in response to Hoechst's inquiries regarding the distribution of breast
implants by Lepetit and otherwise, nothing has come to Dow's attention which has
led Dow to believe that any of the following statements are untrue:
 
                                       23
<PAGE>
 
               (a)  The actual number of breast implants manufactured by Dow
     Corning Corporation which were sold in the countries indicated in Schedule
     17(a) hereto did not exceed in any such country in any year indicated
     therein the number indicated therein as having been sold in such country in
     such year;

               (b)  Lepetit has not sold or distributed any breast implants (i)
     in Italy since 1992, (ii) in Spain or Portugal since 1982 or early 1983 or
     (iii) in any country other than Italy, Spain or Portugal since 1977; and

               (c)  All of the breast implants sold or distributed by Lepetit in
     any of the member countries of the European Community were acquired by
     Lepetit from corporations or other business entities located or domiciled
     in member countries of the European Community (which corporations and
     business entities acted as the importers of such breast implants for
     purposes of the laws of the applicable member countries of the European
     Community).

          18.  This Agreement (i) constitutes the entire agreement among the
Parties hereto with respect to the subject matter hereof and supersedes all
other prior agreements and understandings, both written and oral, among the
parties with respect to the subject matter hereof and (ii) shall not be assigned
by operation of law or otherwise.

                                       24
<PAGE>
 
          19.  All notices, requests, claims, demands and other communications
hereunder shall be in writing and shall be given (and shall be deemed to have
been duly given upon receipt) by delivery in person, by facsimile or by
registered or certified mail (postage prepaid, return receipt requested), to the
other party as follows:

          if to Hoechst:

                 Hoechst Corporation
                 Route 202-206
                 P.O. Box 2500
                 Somerville, New Jersey  08876-1258
                 Fax: 908-231-4848
                 Attention: Harry R. Benz

          with copies to:

                 Hoechst AG
                 65926 Frankfurt am Main
                 Germany
                 Fax: 011-49-69-319-113
                 Attention: Peter Schuster


                 and

                 Skadden, Arps, Slate, Meagher & Flom
                 919 Third Avenue
                 New York, New York  10022
                 Fax: 212-735-2000
                 Attention:   Roger S. Aaron
                                   and
                            Franklin M. Gittes

                                      25
<PAGE>
 
          if to MMD:

                 Marion Merrell Dow Inc.
                 9300 Ward Parkway
                 Kansas City, Missouri  64114
                 Fax: 816-966-3805
                 Attention: General Counsel

          with copies to:

                 Shook, Hardy & Bacon PC
                 One Kansas City Place
                 1200 Main Street
                 Kansas City, Missouri  64105-2118
                 Fax: 816-421-5547
                 Attention:  Jennings J. Newcom
                                    and
                             Randall B. Sunberg

          if to Dow or the Dow Insurance Subsidiaries:

                 The Dow Chemical Company
                 2030 Dow Center
                 Midland, Michigan  48674
                 Fax:  517-636-0861
                 Attention: Jane M. Gootee


          with a copy to:

                 Mayer, Brown & Platt
                 190 South LaSalle Street
                 Chicago, Illinois  60603-3441
                 Fax:  312-701-7711
                 Attention:  Scott J. Davis

or to such other address as the person to whom notice is given may have
previously furnished to the other in writing in the manner set forth above.

                                      26
<PAGE>
 
          20.  The representations of Dow set forth in Section 17 shall survive
indefinitely.

          21.  This Agreement shall be governed by and construed in accordance
with the law of the State of Delaware, without regard to the principles of
conflicts of law thereof.

          22.  The parties hereto agree that irreparable damage would occur in
the event any provision of this Agreement was not performed in accordance with
the terms hereof and that the parties shall be entitled to specific performance
of the terms hereof, in addition to any other remedy at law or in equity.

                                      27
<PAGE>

IN WITNESS WHEREOF, each of the Parties has caused this Agreement to be executed
on its behalf by its representatives thereunto duly authorized, all as of the
day and year first above written.

The Dow Chemical Company               Dorinco Reinsurance Company



By: /s/ John C. Lillich                By: /s/ Paul D. Brink
   --------------------------------       -------------------------------------
   John C. Lillich                        Paul D. Brink
   Corporate Director of                  President
   Mergers & Acquisitions



Marion Merrell Dow Inc.                Dorintal Reinsurance Ltd.



By: /s/ Fred W. Lyons, Jr.             By: /s/ Daniel A. Marino
   --------------------------------       -------------------------------------
   Fred W. Lyons, Jr.                     Daniel A. Marino
   Chairman and Chief                     Assistant Vice President
   Executive Officer



Hoechst Corporation                    Timber Insurance Ltd.



By: /s/ Harry S. Benz                  By: /s/ Philip M. Roels
   --------------------------------       -------------------------------------
   Harry S. Benz                          Philip M. Roels
   Secretary and Treasurer                Vice President




                                      28

<PAGE>
 
                       MANUFACTURING AGREEMENT AMENDMENT


This Manufacturing Agreement Amendment ("Amendment") is effective as of the date
of purchase of shares of stock of Marion Merrell Dow Inc., a Delaware
corporation with its principal place of business in Kansas City, Missouri
("MMD"), owned by The Dow Chemical Company, a Delaware corporation with its
principal place of business in Midland, Michigan ("DOW"), by H Pharma
Acquisition Corp., a Delaware corporation.  This Amendment between DOW and
Merrell Dow Pharmaceuticals, Inc., a Delaware corporation with its principal
place of business in Cincinnati, Ohio and a wholly-owned subsidiary of MMD
("MDPI"), amends the Manufacturing Agreement between DOW and MDPI dated April 1,
1992 ("Manufacturing Agreement").

DOW and MDPI agree as follows:

1.   This Amendment adopts the defined terms stated in the Manufacturing
     Agreement.

2.   Section 2.2(e) is amended and replaced in its entirety with the following:

     (e)    For each year beginning with 1996, shall pay to DOW
     (i)    a Fee of $9,700,000 per year payable in accordance with Section 4.3;
     (ii)   plus $300,000 per year for reimbursement of General Administrative
            Costs;
     (iii)  plus a sum for Gain Sharing as formalized between the parties in the
            Operating Principles.  Gain Sharing shall be subject to a $500,000
            yearly cap.

3.   Section 14.1 is amended and replaced in its entirety with the following:

     14.1  Term.  The term of this Agreement shall commence on April 1, 1992 and
     extend until June 30, 2000.  The Agreement shall be automatically extended
     for two additional one year periods through June 30, 2002, unless
     terminated under Section 14.2.

4.   Section 14.2 is amended and replaced in its entirety with the following:

     14.2  Termination.

     (a) Either party shall have the right to terminate this Agreement effective
     June 30, 2000 or June 30, 2001 

<PAGE>
 
     by providing the other party with at least three years' prior written
     notice of termination.

     (b) MDPI may terminate the manufacture of any given Substance at the end of
     a calendar quarter by providing one years' prior written notice to DOW.
     Such termination shall not relieve MDPI of responsibility for payment of
     the Fee, General Administrative Costs, or Gain Sharing as stated in Section
     2.2; however, Dow shall use its reasonable best efforts to reduce
     Production Costs for the remaining Substances due to reduction in the
     number of Substances being produced in the Dedicated Facilities.  If any
     accepted orders for a Substance which is terminated are outstanding when
     termination was supposed to occur, then such termination shall not be
     effective until completion of the outstanding orders.

5.   Section 16.8 is amended and replaced in its entirety with the following:

     16.8  Disposition of Dedicated Facilities.  MDPI must sell to DOW and DOW
     must purchase from MDPI, the Dedicated Facilities upon termination of this
     Agreement.  The purchase price is to be sixty percent of the residual book
     value of the Dedicated Facilities at the time of termination of this
     Agreement.  For the purpose of making this calculation, the parties agree
     that as of April 1, 1995 the book value of the Dedicated Facilities
     (assuming and including the completion of projects in progress) was
     $92,000,000.  The parties agree that the residual book value of the
     Dedicated Facilities shall be based on a 10 year straight line depreciation
     from April 1, 1995.  Any capital spent by MDPI (other than capital for the
     completion of the projects in progress on April 1, 1995) to maintain,
     improve or add to the Dedicated Facilities shall be MDPI's responsibility
     and DOW shall have no obligation to pay MDPI for such improvements to the
     Dedicated Facilities unless otherwise agreed in writing.  Therefore,
     assuming completion of projects in progress on April 1, 1995, if the
     Agreement terminates on June 30, 2000, DOW shall pay to MDPI $27,600,000
     for the Dedicated Facilities.  The Dedicated Facilities will be sold as is,
     where is, and with a warranty that the facilities are free and clear of any
     lawful security interests or liens but with no other warranties.

6.   DOW and MDPI may decide to extend the manufacturing relationship addressed
in this Amendment and the Manufacturing Agreement. To the extent that the
parties have negotiations regarding an extension of the term of the
Manufacturing Agree-

                                       2
<PAGE>
 
ment, DOW agrees to include in those discussions the possibility for paying to
MDPI an increased percentage of the residual book value of the Dedicated
Facilities as stated in Section 16.8 of the Manufacturing Agreement.

7.   The parties agree that to the extent this Amendment is inconsistent with
the Ground Lease, this Amendment supersedes the Ground Lease.  Upon DOW's
purchase of the Dedicated Facilities from MDPI, the parties agree that the
Ground Lease simultaneously terminates to the extent that it applies to the
Dedicated Facilities.  Notwithstanding the foregoing, MDPI shall not be released
from its obligations under Article XIV of the Ground Lease regarding the
Dedicated Facilities except that MDPI shall be relieved of any responsibility
under Article XIV(a) to remove, demolish, and dispose of any Buildings and
Equipment; and DOW shall not be released from its obligations under Article
XVIII of the Ground Lease.

8.   All of the other terms and conditions of the Manufacturing Agreement
continue in full force and effect.

                                       3
<PAGE>
 
The parties have caused this Agreement to be executed by their duly authorized
representatives.

THE DOW CHEMICAL COMPANY               MERRELL DOW PHARMACEUTICALS, INC.



/s/ Enrique C. Falla                   /s/ Charles D. Dalton
- --------------------                   ---------------------
Name:  Enrique C. Falla                Name:  Charles D. Dalton
Title: Executive Vice                  Title: Vice President
       President and
       Chief Financial
       Officer

                                       4

<PAGE>
   
                 SECOND AMENDMENT TO MASTER SERVICE AGREEMENTS


          This Second Amendment to the Master Service Agreements ("Amendment")
is effective as of the date of purchase of shares of stock of Marion Merrell Dow
Inc., a Delaware corporation with its principal place of business in Kansas
City, Missouri ("MMD"), owned by The Dow Chemical Company, a Delaware
corporation with its principal place of business in Midland, Michigan ("DOW"),
by H Pharma Acquisition Corp., a Delaware corporation (the "Effective Date").
This Amendment is by and among MMD, DOW and Merrell Dow Pharmaceuticals Inc., a
Delaware corporation with its principal place of business in Cincinnati, Ohio
and a wholly-owned subsidiary of MMD ("MDPI").

          WHEREAS, MMD and MDPI each made a Master Service Agreement dated as of
December 2, 1989 with DOW, which Master Service Agreements were amended by the
parties in amendments dated January 1, 1992 and May 3, 1995;

          WHEREAS, MMD, MDPI and DOW desire to clarify rights and obligations
associated with research and development services provided by DOW under the
Master Service Agreements; and

          WHEREAS, MMD, MDPI and DOW desire to modify the notice of termination
provisions, the duration of certain services and clarify the compensation to be
owed to DOW for all services performed under the Master Service Agreements.

MMD, MDPI and DOW agree as follows:

1.  This Amendment adopts the terms "Dedicated Facilities" and "Midland
Facility" as those terms are defined in the Manufacturing Agreement between MDPI
and DOW dated April 1, 1992, as amended ("Manufacturing Agreement").

2.  "Research Services" means the research and development services described in
Section 2(e) of the Master Service Agreement between DOW and MDPI at the Midland
Facility.  The Research Services shall include but not be
limited to the following types of activity:  (a) supply of bulk drug substances
for pre-clinical and clinical testing; (b) lab and pilot plant capability; (c)
raw 

<PAGE>
 
material source identification and qualification in conjunction with MMD
personnel; (d) process experience to establish drug substance specifications;
(e) process development information to support process registration; (f) in
process analytical development and quality control methods; (g) support for the
writing of INDs, DMFs and NDAs; (h) status reports on a quarterly basis; (i)
technical and research and development reports on a quarterly basis; (j)
technical and research and development reports on a project; (k) other services
reasonably required to support a project or as may be agreed to by the parties.
It is the intent of the parties that the Research Services shall be of a similar
nature to those process development and research services provided by DOW to
MDPI under the Master Service Agreement immediately prior to the date of this
Amendment.

3.  For Research Services only, the term provided for in Section 1 of the Master
Service Agreement between MMD and DOW and Section 1(a) of the Master Service
Agreement between MDPI and DOW shall be amended to extend until June 30, 2000.
This term as applied to Research Services shall be automatically extended for
two additional one year periods through June 30, 2002, unless otherwise
terminated according to this Amendment.  Either MMD or MDPI, respectively, or
DOW may terminate the respective Master Service Agreement as applied to Research
Services at the end of a term by giving the other party three years' prior
written notice of termination.  The shorter termination notice provision for
individual services stated in the January 1, 1992 Amendment to Master Service
Agreements does not apply to Research Services.  MDPI may add or discontinue
projects in the ordinary course of business as has been the practice of MDPI
prior to the date of this Amendment.

4.  For Research Services only, until notice of termination is given, the fixed
annual amount as described in Section 4(a) of the Master Service Agreement
between MDPI and DOW may not decline by more than fifteen percent per calendar
year from the level existing the prior calendar year.  The 1995 fixed annual
amount shall be adjusted pro rata by paragraph 5 below.  The first calendar year
the fixed annual amount may decline is 1996.  After notice of
termination, the fixed annual amount may not decline by more than fifteen
percent per year the first year and twenty-five percent per year the second
year.  There is 
  
                                       2
<PAGE>
 
no limit on the decline of the fixed annual amount for the final
year.

5.  For all services, including Research Services, performed after the Effective
Date under the Master Service Agreements, MMD and MDPI shall reimburse DOW 130
percent of the amount calculated according to Section 4 of the Master Service
Agreement between MDPI and DOW.  The parties confirm, however, that there is no
30% surcharge on the cost of raw materials purchased by Dow for MMD or MDPI.

6.  Upon termination of the Research Services, MMD and MDPI must sell to DOW and
DOW must buy from MMD and MDPI all physical assets owned by either MMD or MDPI
which are located in the Midland Facility other than the Dedicated Facilities
("Research Facilities").  The Research Facilities include MMD or MDPI assets
that DOW, as of April 1, 1995, directly uses to provide Research Services.  The
purchase price for the Research Facilities is to be sixty percent of the
residual book value of the Research Facilities at the time the Research Services
portion of both Master Service Agreements are terminated.  The purchase price
shall be paid by DOW to MDPI.  For the purpose of making this calculation, the
parties agree that as of April 1, 1995 the book value of the Research Facilities
(assuming and including completion of projects in progress) was $30,500,000.
The parties agree that the residual book value of the Research Facilities shall
be based on a 10 year straight line depreciation from April 1, 1995.  Any
capital spent by MMD or MDPI (other than capital for the completion of projects
in progress on April 1, 1995) to maintain, improve or add to the Research
Facilities shall be either MMD's or MDPI's responsibility, and DOW shall have no
obligation to pay additional sums of money for the Research Facilities unless
otherwise agreed in writing.  Therefore, assuming completion of projects in
progress on April 1, 1995 and assuming termination of the Research Services on
June 30, 2000, then DOW will pay to MDPI $9,150,000 for the Research Facilities.
The Research Facilities will be sold as is, where is, and with a warranty that
the facilities are free and clear of any lawful security interests or liens but
with no other warranties.

  7.  MMD, MDPI and DOW may decide to extend the Research Services relationship
addressed in this Amendment.  To 
     
                                       3
<PAGE>
 
the extent that the parties have negotiations regarding an extension of the term
of the Research Services portion of the Master Service Agreements, DOW agrees to
include in those discussions the possibility of paying an increased percentage
of the residual book value of the Research Facilities at the end of the extended
term. DOW and MDPI shall mutually agree upon appropriate compensation prior to
DOW being permitted by MDPI to use the Research Facilities for DOW's own
purposes (during the term of the Research Services portion of the Master Service
Agreement between MDPI and DOW) unrelated to the Research Services.

8.  The parties agree that to the extent this Amendment is inconsistent with the
Ground Lease between MDPI and DOW dated April 1, 1992 ("Ground Lease"), this
Amendment supersedes the Ground Lease.  Upon DOW's purchase of the Research
Facilities, the parties agree that the Ground Lease simultaneously terminates to
the extent that it applies to the Research Facilities.  Notwithstanding the
foregoing, MDPI shall not be released from its obligations under Article XIV of
the Ground Lease regarding the Research Facilities except that MDPI shall be
relieved of any responsibility under Article XIV(a) to remove, demolish, and
dispose of any Buildings and Equipment; and DOW shall not be released from its
obligations under Article XVIII of the Ground Lease.

9.  Except as modified herein, all of the other terms and conditions of the
Master Service Agreements continue in full force and effect.

                                       4
<PAGE>
 
The parties have caused this Amendment to be executed by their duly authorized
representatives.

THE DOW CHEMICAL COMPANY               MERRELL DOW
                                       PHARMACEUTICALS INC.


/s/ Enrique C. Falla                   /s/ Charles D. Dalton
- ------------------------               ----------------------
Name:  Enrique C. Falla                Name:  Charles D. Dalton
Title: Executive Vice                  Title: Vice President
       President and
       Chief Financial
       Officer
                                       MARION MERRELL DOW INC.


                                       /s/ Charles D. Dalton
                                       ----------------------
                                       Name:  Charles D. Dalton
                                       Title: Vice President

                                       5

<PAGE>
 
                  THIRD AMENDMENT TO MASTER SERVICE AGREEMENTS


          This Third Amendment to the Master Service Agreements ("Amendment") is
effective as of the date of purchase of shares of stock of Marion Merrell Dow
Inc., a Delaware corporation with its principal place of business in Kansas
City, Missouri ("MMD"), owned by The Dow Chemical Company, a Delaware
corporation with its principal place of business in Midland, Michigan ("DOW"),
by H Pharma Acquisition Corp., a Delaware corporation (the "Effective Date").
This Amendment is by and among MMD, DOW and Merrell Dow Pharmaceuticals Inc., a
Delaware corporation with its principal place of business in Cincinnati, Ohio
and a wholly-owned subsidiary of MMD ("MDPI").

          WHEREAS, MMD and MDPI each made a Master Service Agreement dated as of
December 2, 1989 with DOW, which Master Service Agreements were amended by the
parties in amendments dated January 1, 1992 and May 3, 1995:

          WHEREAS, MMD, MDPI and DOW desire to clarify rights and obligations
associated with services provided by DOW under the Master Service Agreements.

          NOW THEREFORE, the parties agree as follows:

          1.  It is the general intent of MMD, MDPI, DOW and their respective
subsidiaries around the world to disengage from the various service agreements
on a global basis as soon as practical and in a reasonable manner after DOW
sells its shares of MMD's stock. The parties intend and acknowledge that outside
of the USA the disengagement will be managed by the local DOW and MMD
subsidiaries, taking into account local needs and the local service agreements.

          2.  Pursuant to Section 3 of the Amendment to Master Service Agreement
dated January 1, 1992, MMD and MDPI hereby give DOW notice that as of the date
that DOW sells its shares in MMD (or as soon thereafter as is practical and
reasonable), MMD and MDPI are terminating the following services on a global
basis: Treasury, Payroll, Human Resources, Tax, Legal, and Waste Disposal (other
than waste generated at the Midland Facility). By
<PAGE>
 
its acknowledgment, as indicated below, DOW hereby waives the 90
days' written notice of termination regarding the above referenced services.

          3.  After the date DOW sells its shares in MMD, DOW shall cause its
subsidiaries to continue to provide to MMD or its subsidiaries the services
currently being provided under the terms of the local services agreements, and:

          (i) Human Resources services for benefits administration in Canada
     through June 30, 1996;

          (ii) information systems services in Japan, Korea, Hong Kong, New
     Zealand, and Australia through 1996; and

          (iii) cost accounting and purchasing services in Europe until the
     PRIZM system becomes operational or the end of 1996, whichever occurs
     first.

          4.   DOW agrees that various principles of operations (e.g.
information systems, telecommunications services, treasury services, accounting
guidelines, and Pharma Plant operation guidelines) shall continue in place until
the related services have been terminated.

          5.   For all services performed after the Effective Date under the
Master Service Agreements, MMD and MDPI shall reimburse DOW 130 percent of the
amount calculated according to Section 4 of the Master Service Agreement between
MDPI and DOW.

          6.   At DOW's discretion DOW may waive the 90 day notice of
termination regarding future terminations for any service.

          The parties and their subsidiaries will continue to work together to
provide a smooth transition and disengagement from DOW provided services.

                                       2
<PAGE>
 
          The parties have caused this Amendment to be executed by their duly
authorized representatives.

THE DOW CHEMICAL COMPANY      MERRELL DOW PHARMACEUTICALS INC.



/s/ Enrique C. Falla            /s/ Charles D. Dalton
- --------------------            ---------------------
Name:  Enrique C. Falla       Name:  Charles D. Dalton
Title: Executive Vice         Title: Vice President
       President and
       Chief Financial
       Officer
                              MARION MERRELL DOW INC.



                              /s/ Charles D. Dalton
                              ---------------------
                              Name:  Charles D. Dalton
                              Title: Vice President

                                       3

<PAGE>
 
                    [LETTERHEAD OF MARION MERRELL DOW INC.]


                                                                   May 3, 1995



The Dow Chemical Company
Attention:  General Counsel
2030 Willard H. Dow Center
Midland, Michigan  48674

     Re:  Employment Matters, Certain Italian Personnel
          ---------------------------------------------

          In conjunction with the execution of the Stock Purchase Agreement of
this date (the "Agreement") among The Dow Chemical Company ("DCC"), Hoechst
Corporation ("Hoechst") and certain of their subsidiaries, this letter is
intended to set forth provisions relating to the above referenced matters.
Defined terms used in the Agreement shall have the same meanings when used
herein as are attributable to them under the Agreement.

          With respect to employment matters, DCC has no objection to and will
cause Dow Italia S.p.A. ("Dow Italia") to agree that the following five (5) Dow
Italia employees shall be transferred to Gruppo Lepetit S.p.A. ("Gruppo
Lepetit") as of the date of Hoechst's purchase of the Dow Shares:  Costantino
Ambrosio, Director of Manufacturing, Italy; Daniele Bosatra, European Bulk Sites
E&HS Manager; Flavio Caluri, Process Control/MOD Engineer; and Luigi Grippa,
Italian Engineering Manager; and Marilena Serpico, Administrative Assistant.
The individuals shall resign and shall be hired the same day by Gruppo Lepetit.
Marion Merrell Dow Inc. has no objection to and will cause Gruppo Lepetit to
hire the five people on the day each of them resigns from Dow Italia.  Dow
Italia shall not pay any costs or indemnities other than accrued severance
allowances.  FIP Dow will be handled separately and according to applicable
regulations.
<PAGE>
The Dow Chemical Company
May 3, 1995
Page 2
 
          DCC further has no objection to and will cause Dow Italia  to agree
that Dow Italia will not offer employment to, or employ, any current Dow Italia
employees who, immediately preceeding the Closing Date under the Agreement, were
employed at, supporting or operating the Gruppo Lepetit plants located in Italy
for a period of one year after the Closing Date.  DCC also has no objection to
and  will cause Dow Italia to agree and to act in good faith according to
regulations so that all severance allowances, and other benefits (FIP Dow will
be handled separately and according to applicable regulations), if any, or other
accounts attributable (i) to the foregoing five employees, (ii) to all other
employees of Dow Italia who are being transferred to Gruppo Lepetit pursuant to
the Manufacturing Services Agreement dated December 21, 1990, as amended, on the
date of Hoechst's purchase of Dow Shares pursuant to the Agreement and (iii) to
other employees, if any, of an MMD subsidiary participating in Italian benefit
plans, shall be transferred, if under Dow Italia's control, to the MMD legal
entity responsible for such employee as of the Closing Date according to local
regulations.

          DCC also has no objection to and will cause its relevant subsidiary to
agree that all severance allowances, and other benefits, if any, or other
accounts attributable to MMD employees who participate in benefit plans, if any,
of Dow subsidiaries in Portugal, Switzerland and the U.K. shall be transferred,
if under a Dow subsidiary's control, to the MMD legal entity responsible for
such employee as of and after the Closing Date according to local regulations.

          DCC and MMD further agree that as of the date of Hoechst's purchase of
Dow Shares pursuant to the Agreement, the Manufacturing Services Agreement
between Dow relevant subsidiaries on the one hand and (a) MMD GmbH dated
December 9, 1993, (b) MMD Limited dated December 21, 1993, (c) MMD S.A. dated
December 27, 1993, (d) MMD & Cie SNC dated December 27, 1993, (e) MMD S.A. dated
January 3, 1994, and (f) Gruppo Lepetit dated December 21, 1990, respectively,
as subsequently amended,
<PAGE>
The Dow Chemical Company
May 3, 1995
Page 3
 
will terminate by mutual consent without further action of the parties.

                              MARION MERRELL DOW INC.



                              By /s/ Charles D. Dalton
                                 ---------------------


                              THE DOW CHEMICAL COMPANY



                              By /s/ Jane M. Gootee
                                 ---------------------

<PAGE>
 
                    [LETTERHEAD OF MARION MERRELL DOW INC.]




                                                                     May 3, 1995



The Dow Chemical Company
Attention:  General Counsel
2030 Willard H. Dow Center
Midland, Michigan  48674

          Re:  Nonexclusive List of Agreements to be 
               Reached Prior to Stock Purchase
               -------------------------------------

Dear Sirs:

          In order to expedite the execution of the Stock Purchase Agreement and
the Agreement and Plan of Merger, The Dow Chemical Company ("DCC"), Marion
Merrell Dow Inc. ("MMD"), and Merrell Dow Pharmaceuticals Inc. ("MDPI") agree
that between the date of this letter and the purchase of DCC's Shares pursuant
to the Stock Purchase Agreement, the parties shall use best efforts to reach
definitive agreements on, but not limited to, the matters listed below to the
extent that such agreements have not been reached on or prior to the date
hereof:

          (i) DCC's assistance in transferring to MMD or MDPI all technology
     owned by or licensed to MMD or MDPI;

          (ii) confirmation of ownership of intellectual property rights of MMD,
     MDPI and DCC;

          (iii) the grant to MMD or MDPI by DCC of an option for a non-
     exclusive, worldwide license to certain DCC patents relating to a fiber
     optic probe and related technologies;

          (iv) the ownership and cross-licensing by MMD or MDPI and DCC of
     future inventions and developments relating to technology developed in
     connection with the Master Service Agreements, dated December 2, 1989, or
     the
<PAGE>
 
The Dow Chemical Company
May 3, 1995
Page 2


     Manufacturing Agreement between DCC and MDPI, dated April 1, 1992, both as
     amended;

          (v) MMD's ability to use DCC's Indianapolis toxicology laboratories on
     a nonexclusive basis;

          (vi) Dow's acknowledgement of MMD's or MDPI's ownership of the results
     of the engineering work performed for DCC relating to the construction of a
     new plant for AllerVax (R) products;

          (vii) the provision of services to Dow Italia S.p.A. at the Garessio
     plant relating to the milling of cholestyramine;

          (viii) the extension of the term of the Methocel Supply Agreement
     dated October 1, 1993 between MMD and DCC for three (3) years from the end
     of its existing term;

          (ix) to the extent required, the continuation of non-manufacturing
     services currently provided by Dow Italia S.p.A. to Gruppo Lepetit S.p.A.
     under the Manufacturing Services Agreement dated December 21, 1990, as
     amended; and

          (x) such other matters as either MMD or DCC may desire.

          If the parties are unable to reach agreement on any of the above
matters after using good faith efforts to do so, such unresolved matters shall
be referred to
<PAGE>
 
The Dow Chemical Company
May 3, 1995
Page 3


Klaus Schmieder of H Pharma Acquisition Corp. and Enrique Falla of DCC for
resolution.


MARION MERRELL DOW INC.       MERRELL DOW PHARMACEUTICAL INC.



By: /s/ Charles D. Dalton     By: /s/ Charles D. Dalton
   -----------------------       -----------------------
Name:  Charles D. Dalton      Name:  Charles D. Dalton
Title: Vice President         Title: Vice President


Acknowledged and Agreed:

THE DOW CHEMICAL COMPANY



By: /s/ Jane M. Gootee
   -------------------
Name:  Jane M. Gootee
Title: Manager, Financial Law


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