Exhibit 10.68

         AMENDMENT AND AGREEMENT, dated as of the 31st day of January, 1997 
(this "Amendment"), by and among PharmaGenics, Inc., a Delaware corporation 
(the "Company"), and PaineWebber R&D Partners III, L.P., a Delaware limited 
partnership (the "Fund").

                                      BACKGROUND

         A.   The Company and the Fund are parties to a Stock Purchase 
Agreement, dated as of March 15, 1995 (the "Stock Purchase Agreement"), along 
with the Program Agreement, dated as of April 1, 1994, as amended on March 
15, 1995 (the "Program Agreement"), the Related Agreements and the Warrants, 
as amended and restated (unless otherwise defined herein, terms used herein 
shall have the meanings set forth in the Program Agreement, and the Amended 
and Restated Glossary thereto).

         B.   The Company has entered into a merger agreement dated as of 
January 31, 1997, in substantially the form attached hereto as Exhibit A (the 
"Merger Agreement"), with Genzyme Corporation, a Massachusetts corporation 
("Genzyme"), pursuant to which the Company will be merged with and into 
Genzyme (the "Merger"), with Genzyme surviving the Merger.

         C.   As a result of the Merger, (i) all shares of the Company's 
Series A Convertible Preferred Stock ("Series A Stock"), Series B Convertible 
Preferred Stock ("Series B Stock"), and Series C Convertible Preferred Stock 
("Series C Stock") (the Series A Stock, Series B Stock and Series C Stock 
shall collectively be referred to as the "Preferred Stock") outstanding 
immediately prior to the effective time of the Merger (other than shares held 
by the Company as treasury stock, dissenting shares and shares owned by 
Genzyme) will be converted into shares of Genzyme Molecular Oncology Division 
Common Stock to be allocated among the holders of the Preferred Stock in 
accordance with the Merger Agreement and (ii) all shares of the Company's 
common stock will be cancelled.  

         D.   In contemplation of the Merger and as a result of the Company 
not having a sufficient number of shares of Series C Stock in order to 
deliver the additional Securities contemplated by Section 3.2 of Article I of 
the Stock Purchase Agreement, the parties desire to amend the Stock Purchase 
Agreement to provide that, upon the exercise of the Fund's conversion right 
thereunder, the Company will issue to the Fund shares of Preferred Stock as 
set forth herein.  

         In consideration of the mutual covenants expressed herein and for 
other good and valuable consideration, the receipt and adequacy of which are 
hereby acknowledged, the Company and the Fund hereby agree to amend the Stock 
Purchase Agreement as set forth below.  




                                      ARTICLE I

         SECTION 1.     Section 3.1(b) of Article I of the Stock Purchase 
Agreement is hereby amended and restated as follows:  

         (b)  If the Fund exercises its option pursuant to Section 3.1(a), the
    Fund shall execute such proper assignments and instruments as are
    reasonably necessary or advisable to accomplish and record such transfer
    and assignment and to establish the ownership of the Company in and to the
    Fund Technology, Background Technology, Targets and related Products and
    Abandoned Targets and related Products.


         SECTION 2.     Section 3.2 of Article I of the Stock Purchase 
Agreement is hereby amended and restated as follows:   

         3.2  Securities to be Issued; Number of Shares. Notwithstanding
    anything to the contrary herein, in lieu of the additional Securities
    described in Section 3.1(a), upon exercise of its option pursuant to
    Section 3.1(a), the Company shall issue to the Fund  298,420 shares of
    Series A Stock, 88,864 shares of Series B Stock and 1,641,144 shares of
    Series C Stock.

                                      ARTICLE II

         SECTION 1.     Effect of Amendment.  Except as amended hereby, the 
provisions of the Stock Purchase Agreement, Program Agreement, Related 
Agreements and Warrants shall remain in full force and effect, as so amended.

         SECTION 2.     Counterparts.  This Amendment may be executed in one 
or more counterparts, all of which shall be considered one and the same 
agreement and shall become effective when one or more counterparts have been 
signed by each of the parties and delivered to the other parties.

         SECTION 3.     Entire Agreement; No Third-Party Beneficiaries.  
Other than the Stock Purchase Agreement (and subject to Section 6.4 thereof), 
the Program Agreement, the Related Agreements and the Warrants, this 
Amendment (a) constitutes the entire agreement, and supersedes all prior 
agreements and understandings, both written and oral, among the parties with 
respect to the subject matter of this Amendment and (b) is not intended to 
confer upon any person other than the parties hereto any rights or remedies.

         SECTION 4.     Choice of Law.  This Amendment shall be construed and 
enforced in accordance with the laws of the State of Delaware, without regard 
to the conflicts of law rules of such state.

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         SECTION 5.     Assignment.  This Amendment may not be assigned, 
delegated, transferred or sold, in whole or in part, by either of the parties 
hereto.  

         SECTION 6.     Severability.  If any provision of this Amendment is, 
becomes or is deemed invalid, illegal or unenforceable in any jurisdiction, 
such provision shall be  stricken and the remainder of the Amendment shall 
remain in full force and effect.

         SECTION 7.     Headings.  Article and Section headings contained in 
this Amendment are included for convenience only and are not to be used in 
construing or interpreting this Amendment.

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         IN WITNESS WHEREOF, the Company and the Fund have executed this 
Amendment as of the date and year first above written.

                               PAINEWEBBER R&D PARTNERS III, L.P.

                               By:  PAINEWEBBER DEVELOPMENT
                                    CORPORATION, General Partner


                               By:        /s/ Dhananjay Pai                 
                                    ________________________________________
                                    Name:  Dhananjay Pai
                                    Title: President


                               PHARMAGENICS, INC.


                               By:          /s/ Michael I. Sherman           
                                    _________________________________________
                                    Name:  Michael I. Sherman
                                    Title: President


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