SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549



SCHEDULE 13G



Under the Securities Exchange Act of 1934

(Amendment No. 2)*



                     Name of Issuer:  Perseptive Biosystems, Inc.



          Title of Class of Securities:  Common Stock, Par $.01



                            CUSIP Number:  715271 102



*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 the
disclosures provided in a prior cover page.



The information required in 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).









CUSIP No. 715271 102



1.  NAME OF REPORTING PERSON

    S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON



Firstar Investment Research & Management Company



2.  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*



(a)  [ ]

(b)  [x]



3.  SEC USE ONLY







4.  CITIZENSHIP OR PLACE OF ORGANIZATION



State of organization:  Wisconsin



NUMBER OF    5.  SOLE VOTING POWER



 SHARES          174,900



BENEFICIALLY 6.  SHARED VOTING POWER



  OWNED BY       321,400



    EACH     7.  SOLE DISPOSITIVE POWER



  REPORTING      209,300



   PERSON    8.  SHARED DISPOSITIVE POWER



    WITH         321,400



9.  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON



530,700 shares



10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
CERTAIN SHARES*



[ ]



11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9



2.5%



12.  TYPE OF REPORTING PERSON*



IA





Item 1(a).  Name of Issuer:



Perseptive Biosystems, Inc.



Item 1(b).  Address of Issuer's Principal Executive Offices:



500 Old Connecticut Path

Framingham, Massachusetts 01701



Item 2(a).  Name of Person Filing:



Firstar Investment Research & Management Company



Item 2(b).  Address of Principal Business Office or, if none,
Residence:



777 E. Wisconsin Avenue

Milwaukee, Wisconsin 53202



Item 2(c).  Citizenship:



State of organization:  Wisconsin



Item 2(d).  Title of Class of Securities:



Common Stock, Par $.01



Item 2(e).  CUSIP Number:



715271 102



Item 3.  If this statement is filed pursuant to Rules 13d-1(b),
or 13d-2(b), check whether the person filing is a:



(a)  [ ]  Broker or Dealer registered under section 15 of the Act



(b)  [ ]  Bank as defined in section 3(a)(6) of the Act



(c)  [ ]  Insurance Company as defined in section 3(a)(19) of
the Act



(d)  [ ]  Investment Company registered under section 8 of the
Investment Company Act



(e)  [x]  Investment Adviser registered under section 203 of the
Investment Advisers Act of 1940



(f)  [ ]  Employee Benefit Plan, Pension Fund which is subject
to the provisions of the Employee Retirement Income of 1974 or
Endowment Fund; see 240.13d-1(b)(1)(ii)(F)



(g)  [ ]Parent Holding Company, in accordance with
240.13d-1(b)(ii)(G)  (Note:  See Item 7)



(h)  [ ]  Group in accordance with 240.13d-1(b)(1)(ii)(H)



Item 4.  Ownership:







(a)  Amount Beneficially Owned as of December 31, 1996:



530,700 shares



(b)  Percent of Class:



2.5%



(c)  Number of Shares as to which such person has:



(i)  sole power to vote or to direct the vote:



174,900



(ii)  shared power to vote or to direct to the vote:



321,400



(iii)  sole power to dispose or to direct the disposition of:



209,300



(iv)  shared power to dispose ore to direct the disposition of:



321,400



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 [X].



Item 6.  Ownership of More than Five Percent on Behalf of
Another Person.



Other persons are known to have the right to receive or the
power to direct the receipt of dividends from, or the proceeds
from the sale of, shares beneficially owned by the filing person.



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.



Not Applicable



Item 9.  Notice of Dissolution of Group.



Not Applicable



Item 10.  Certification.



Not Applicable





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.



Date:  February  13, 1997



FIRSTAR INVESTMENT RESEARCH & MANAGEMENT COMPANY







By:  /s/ Jeffrey Squires



Name/Title: Jeffrey Squires, Operations Officer







POWER OF ATTORNEY



With Respect to Section 13 Reports





       Know all men by these present, that the undersigned
hereby constitutes and appoints Jeffrey Squires, Operations
Officer, its true and lawful attorney and agent at any time and
from time to time to execute for and on behalf of the
undersigned initial and amended reports on Schedules 13G in
accordance with Section 13(d) of the Securities Exchange Act of
1934 (the "Act") and the rules promulgated thereunder, and to
file the same with the Securities and Exchange Commission.  The
undersigned grants said attorney and agent full power and
authority to do and perform each and every act and thing
requisite, necessary and proper to be done in the exercise of
any of the rights and powers therein granted, hereby ratifying
and confirming all that each said attorney and agent shall
lawfully do or cause to be done by virtue hereof and the rights
and powers herein granted.



         The undersigned hereby acknowledges that the attorney
and agent appointed herein does not assume any responsibilities
of the undersigned under Section 13 of the Act.



         This Power of Attorney shall remain in full force and
effect unless and until revoked by the undersigned by written
notice delivered to said attorney and agent.



         IN WITNESS WHEREOF, the undersigned has caused this
Power of Attorney to be executed as of the  10th  day of
February, 1997.



                          FIRSTAR INVESTMENT RESEARCH &

                          MANAGEMENT COMPANY





                          By: /s/ Mary Ellen Stanek             
                            Mary Ellen Stanek, President