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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
Under the Securities Exchange Act of 1934
(Amendment No. 6)
Strategic Diagnostics, Inc.
(Name of Issuer)
Common Stock
(Title of Class of Securities)
862700101
(CUSIP Number)
December 31, 1999
(Date of Event Which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:
/_x_/ Rule 13d-1(b)
/___/ Rule 13d-1(c)
/___/ Rule 13d-1(d)
* The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which
would alter disclosures provided in a prior cover page.
The information required on the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities
Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of
that section of the Act but shall be subject to all other provisions of
the Act (however, see the Notes).
Potential persons who are to respond to the collection of information
contained in this form are not required to respond unless the form
displays a currently valid OMB control number.
SEC 1745 (3-98) Page 1 of 7
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CUSIP No. 862700101 Page 2 of 7 Pages
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1 NAME OF REPORTING PERSONS
IRS IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
Palo Alto Investors
- ----------------------------------------------------------------
2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)
(a)/ X /
(b)/ /
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3 SEC USE ONLY
- ----------------------------------------------------------------
4 CITIZENSHIP OR PLACE OF ORGANIZATION
California
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NUMBER OF 5 SOLE VOTING POWER
SHARES 0
BENEFICIALLY ---------------------------------------
OWNED BY 6 SHARED VOTING POWER
EACH 1,327,400
REPORTING ---------------------------------------
PERSON 7 SOLE DISPOSITIVE POWER
WITH 0
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8 SHARED DISPOSITIVE POWER
1,327,400
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9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
1,327,400
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10 CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
CERTAIN SHARES (See Instructions)
- ----------------------------------------------------------------
11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
8.1%
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12 TYPE OF REPORTING PERSON (See Instructions)
CO, IA
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CUSIP No. 862700101 Page 3 of 7 Pages
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1 NAME OF REPORTING PERSONS
IRS IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
William Leland Edwards
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2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)
(a)/ X /
(b)/ /
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3 SEC USE ONLY
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4 CITIZENSHIP OR PLACE OF ORGANIZATION
United States
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NUMBER OF 5 SOLE VOTING POWER
SHARES 39,500
BENEFICIALLY ---------------------------------------
OWNED BY 6 SHARED VOTING POWER
EACH 1,327,400
REPORTING ---------------------------------------
PERSON 7 SOLE DISPOSITIVE POWER
WITH 39,500
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8 SHARED DISPOSITIVE POWER
1,327,400
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9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
1,366,900
- ----------------------------------------------------------------
10 CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
CERTAIN SHARES (See Instructions)
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11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
8.4%
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12 TYPE OF REPORTING PERSON (See Instructions)
IN
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CUSIP No. 862700101 13G Page 4 of 7 Pages
ITEM 1.
(a) The name of the issuer is Strategic Diagnostics, Inc.
(the "Issuer").
(b) The principal executive office of the Issuer is located at
111 Pencader Drive, Newark, DE 19702.
ITEM 2.
(a) The names of the persons filing this statement are Palo Alto
Investors ("PAI") and William Leland Edwards ("Edwards"),
(collectively, the "Filers").
(b) The principal business office of PAI and Edwards is
located at 470 University Avenue, Palo Alto, CA 94301.
(c) See Item 4 of the cover sheet for each Filer.
(d) This statement relates to shares of common stock of the Issuer
(the "Stock").
(e) The CUSIP number of the Stock is 862700101.
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CUSIP No. 862700101 13G Page 5 of 7 Pages
ITEM 3. If this statement is filed pursuant to rule 240.13d-1(b) or
240.13d-2(b) or (c), check whether the person filing is a:
(a) ___ Broker or dealer registered under section 15 of the Act (15
U.S.C. 78o).
(b) ___ Bank as defined in section 3(a)(6) of the Act (15 U.S.C.
78c).
(c) ___ Insurance company as defined in section 3(a)(19) of the Act
(15 U.S.C. 78c).
(d) ___ Investment company registered under section 8 of the
Investment Company Act of 1940 (15 U.S.C. 80a-8).
(e) ___ An investment adviser in accordance with 240.13d-
1(b)(1)(ii)(E).
(f) ___ An employee benefit plan or endowment fund in accordance
with 240.13d-1(b)(1)(ii)(F).
(g) ___ A parent holding company or control person in accordance
with 240.13d-1(b)(1)(ii)(G)
(h) ___ A savings association as defined in section 3(b) of the
Federal Deposit Insurance Act (12 U.S.C. 1813).
(i) ___ A church plan that is excluded from the definition of an
investment company under section 3(c)(14) of the Investment Company Act of
1940 (15 U.S.C. 80a-3).
(j) _xx__Group, in accordance with section 240.13d-1(b)(1)(ii)(J)
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CUSIP No. 862700101 13G Page 6 of 7 Pages
ITEM 4. OWNERSHIP
See Items 5-9 and 11 on the cover sheet for each Filer.
ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS
If this statement is being filed to report the fact that as of the date
hereof the reporting person has ceased to be the beneficial owner of more
than five percent of the class of securities, check the following / /.
ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON
PAI is a registered investment adviser whose clients have the right to
receive or the power to direct the receipt of dividends from, or the
proceeds from the sale of, the Stock. No individual client holds more
than five percent of the outstanding Stock.
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CUSIP No. 862700101 13G Page 7 of 7 Pages
ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH
ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY
Not applicable.
ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP
See Item 2(a) of this Schedule.
ITEM 9. NOTICE OF DISSOLUTION OF GROUP
Not applicable.
ITEM 10. CERTIFICATION
By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were not acquired and are not held for
the purpose of or with the effect of changing or influencing the control
of the issuer of the securities and were not acquired and are not held in
connection with or as a participant in any transaction having that purpose
or effect.
SIGNATURE
After reasonable 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: February 10, 2000
PALO ALTO INVESTORS
By: /s/ William L. Edwards
William L. Edwards, President
/s/ William Leland Edwards
William Leland Edwards
CSR/4325/002/1086066
