***Biogen,  Inc. has omitted from this Exhibit  10.1.1  portions of the
Agreement for which Biogen, Inc. has requested  confidential  treatment from the
Securities  and Exchange  Commission.  The portions of the  Agreement  for which
confidential  treatment  has been  requested are marked with X's in brackets and
such  confidential  portions have been filed  separately with the Securities and
Exchange Commission.***



                             AGREEMENT AND AMENDMENT

         This  Agreement and Amendment  (this "Biogen  Amendment") is made as of
this lst day of May, 1998, by and between Biogen, Inc., a corporation  organized
under the laws of the  Commonwealth  of  Massachusetts  and having its principal
place  of  business  at 14  Cambridge  Center,  Cambridge,  Massachusetts  02142
("Biogen"),  and Schering Corporation, a corporation organized under the laws of
the State of New  Jersey  and having its  principal  place of  business  at 2000
Galloping Hill Road, Kenilworth, New Jersey 07033 ("Schering").

                                   WITNESSETH:

         WHEREAS,   Schering  and  Biogen,   as  successor  to  Biogen  N.V.,  a
corporation organized under the laws of the Netherlands Antilles, are parties to
an Exclusive License and Development Agreement, dated December 8, 1979, relating
to human recombinant leukocyte interferon (such agreement, as amended to date by
the Prior Amendments as defined below, the "Biogen-Schering Agreement"); and

         WHEREAS,  certain  patent  rights owned or  controlled  by Schering and
Biogen, on the one hand, and by Hoffmann-La Roche, Inc. ("Roche") and Genentech,
Inc. ("Genentech"), on the other hand, covering the use, manufacture and sale of
the  respective  interferon  alpha  products of Schering  and Roche have been in
dispute as among Biogen, Schering, Roche and Genentech and have been the subject
of  an  interference   proceeding  before  -the  Board  of  Patent  Appeals  and
Interferences  of the United  States  Patent  and  Trademark  Office  ("USPTO"),
entitled David V. Goeddel and Sidney Pestka v. Charles  Weissmann,  Interference
No.  101,601 (the  "Interference"),  which  awarded  priority to the Goeddel and
Pestka Application (the "Roche/Genentech Patent Application") over the Weissmann
Application in the Interference.  This  Interference  decision has been appealed
('Interference  Appeal") to the United States District Court for the District of
Massachusetts (the "Court"); and

         WHEREAS,  all the parties wish to avoid the risk and expense  attendant
upon further  litigation and to settle all claims which have been brought in the
Interference  Appeal,  and in order to accomplish these objectives,  the parties
wish to enter  into a  settlement  agreement  as of the same date  hereof  which
specifies  the terms and  conditions  agreed to by the  parties to  resolve  the
Interference Appeal (the "Settlement Agreement"); and

         WHEREAS, in connection with the Settlement Agreement, Schering, Biogen,
Genentech  and Roche  (where  applicable)  have  agreed to execute  this  Biogen
Amendment and the Fourth Amendment to that certain  agreement dated May 14, 1985
by and between  Schering  and Roche  relating  to  recombinant  human  leukocyte
interferon (such agreement,  as amended by prior amendments  thereto,  dated May
14, 1985, August 27, 1986, and October 9, 1986, the "Roche-Schering  Agreement")
(the  "Fourth  Amendment,"  and the Biogen  Amendment  and the Fourth  Amendment
together, the "Amendments"); and

         WHEREAS,  Schering and Biogen agree to the  assignment of the Weissmann
Application to Schering upon the receipt of all required  governmental  consents
and approvals and the  observance of all  applicable  waiting  periods under the
Hart-Scott-Rodino  Antitrust Improvements Act ("HSR Act") in connection with the
Biogen  Amendment,  the  Fourth  Amendment  and the  Settlement  Agreement  (the
"Governmental Approvals"); and

         WHEREAS,  Schering recognizes that (i) royalty payments might have been
due to Biogen under the Biogen Agreement if the Weissmann  Application prevailed
and (ii) the  payments to be made  hereunder  are made in  consideration  of the
assignment to Schering of the Weissmann Application and the grant to Schering of
the rights set forth in Section 3.2.

         NOW, THEREFORE, in consideration of the mutual covenants and agreements
contained herein,  the parties hereto,  intending to be legally bound, do hereby
agree as follows:

         1.    Definitions.

         1.1. All capitalized  terms used herein and not otherwise defined shall
have the respective earnings set forth in the Biogen-Schering Agreement.

1.2.  "Additional Patent Rights" shall mean any United States patents that shall
issue to  Biogen  from the  following  patent  applications  or any  divisional,
continuation, continuation-in-part, continuing prosecution application, reissue,
renewal or extension thereof or substitute therefor:[xxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxx]; however, U.S. Serial No. 471, 30 1, filed March 3, 1983 is excluded from
this definition.

<PAGE>

         1.3.     "Biogen Patent" shall mean U.S. Patent No. 4,530,901 entitled
"Recombinant DNA Molecules and
Their Use in Producing Interferon-Like Polypeptides," issued on July 23, 1985.

         1.4.  "Prior  Amendments"  shall mean the amendments and supplements to
the Exclusive icense and Development  Agreement dated as of December 8, 1979, by
and between Biogen, Biogen .V., and Biogen N.V. and Schering,  executed prior to
the date hereof,  including without  limitation the following:  (i) Supplemental
Agreement,  dated as of March 11, 1983, by and between Biogen N.V.,  Biogen B.V.
and  Schering;  (ii)  Amendatory  Agreement,  dated as of May 14,  1985,  by and
between  Biogen B.V. and Schering;  (iii)  Amendment and  Settlement  Agreement,
dated as of September 29, 1988 by and between Biogen,  Biogen B.V. and Schering;
(iv)  Amendment,  dated as of March 20,  1989 by and  between  Biogen  B.V.  and
Schering;  (v) Amendment,  dated as of March 23, 1992, by and between Biogen and
Schering;  and (vi) Supplemental  Amendment and Agreement,  dated as of March 1,
1994, by and between Schering and Biogen.

        1.5. "Roche Patent Rights" shall mean any United States patents that
shall issue from patent  applications  owned or controlled by Roche
individually or jointly with Genentech,  that were the subject of the
Interference,  including, but not limited to,[xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxx] or from any divisional,  continuation,  continuation-in-part,
continuing  prosecution application, reissue or extension thereof or substitute
therefor.

         1.6.     "Royalty Termination Date" shall mean (as applicable):

         a) with  respect to  Additional  Patent  Rights for any given  Licensed
Product  or  Licensed  Combination  Product,  the last to expire  of any  issued
Additional  Patent  Rights which has a claim that covers the  manufacture,  use,
offer to sell,  sale,  export or import of such  Licensed  Product  or  Licensed
Combinations Product (both as defined in the Biogen-Schering Agreement); or

         b) with  respect to the Roche  Patent  Rights,  for any given  Licensed
SCHERING  Product the last to expire of any issued Roche Patent Rights which has
a claim that covers the manufacture,  use, sale, offer to sell, export or import
of such Licensed SCHERING Products, as defined by the Roche-Schering  Agreement,
as amended by the Fourth Amendment.

         1.7.     "Weissmann Application" shall mean U.S. Serial No. 471,301
filed March 2, 1983.

         2. Roche Patent  Rights.  Biogen hereby  acknowledges  that Schering is
entering into the Fourth Amendment with Roche under

<PAGE>

which  Roche has  agreed to grant  Schering  an  exclusive  (even as to  Roche),
non-transferable  license  and  an  immunity  from  suit  under  the  Roche  and
Roche/Genentech  Patent  Rights  for use  solely  within  the  United  States to
manufacture,  have manufactured,  import,  export,  use, offer to sell, and sell
Licensed  SCHERING  Products  (as such terms are  defined by the  Roche-Schering
Agreement,  as amended by the Fourth Amendment).  Biogen also acknowledges that,
for consideration  granted herein, it retains no right, title or interest in the
rights granted to Schering by Roche in the Roche-Schering  Agreement, as amended
by the Fourth Amendment.

         3. Assignment of Weissmann Application.

         3.l.  Biogen hereby  agrees to assign,  transfer and convey to Schering
all of its right,  title and  interest in and to the  Weissmann  Application  by
executing  and  delivering,  within  ten  (10)  days of the last to occur of the
Governmental Approvals, an Assignment of Patent Rights substantially in the form
of Exhibit A attached hereto (the "Patent Assignment"). Biogen further covenants
and agrees that it will from time to time,  if requested  by Schering,  execute,
acknowledge  and deliver such  additional  documents and  instruments  as may be
reasonably necessary to effectuate the foregoing assignment.

         3.2. Biogen also agrees that it will assign to Schering, as assignee of
the  Weissmann  Application,   contemporaneously  with  the  assignment  of  the
Weissmann  Application,  the right (i) to contest or consent to the  decision of
the Board of Patent Appeals and  Interferences of the USPTO rendered on December
15, 1995 in the  Interference  and (ii) to take such  actions as Schering in its
sole  discretion  may  determine  in  order  to  carry  on  or to  conclude  the
Interference and the Interference Appeal.

         3.3. If, for any reason,  the Court does not approve,  or withdraws its
approval of, the Settlement  Agreement,  or the Settlement Agreement is declared
null and void ab initio after the assignments contemplated in paragraphs 3.1 and
3.2 herein occur,  then such assignments shall be deemed null and void ab initio
and have no further force and effect and Schering shall execute, acknowledge and
deliver  such  documents  and  instruments  as may be  reasonably  necessary  to
effectuate  the  reassignment  to  Biogen of all  rights  assigned  pursuant  to
Sections 3.1 and 3.2 herein.

         4.    Covenants of Schering.

         4.1.  Schering  hereby  covenants  and agrees that it shall (i) seek to
enforce in a commercially  reasonable matter Article 11 of the Fourth Amendment;
(ii) keep Biogen informed in


<PAGE>

a reasonably prompt manner of all substantive actions of which Schering is aware
have been  taken with  respect to the Roche  Patent  Rights;  and (iii)  provide
Biogen with copies of all substantive filings and substantive correspondence, to
the extent  permissible  under law, with respect to the Roche Patent Rights that
Schering receives from Roche
or any governmental authority.

         4.2.     Schering hereby represents and warrants that, other
than with  respect  to  certain  confidential  financial  terms  which have been
deleted, the copy of the Roche-Schering Agreement provided to Biogen on the date
hereof is true and correct.

         5.     Amendments to the Biogen-Schering Agreement.

         5.1. Section 5.1 of the Biogen-Schering  Agreement is hereby amended by
deleting the second sentence (Le., the first full sentence) beginning on page 29
of the  Biogen-Schering  Agreement,  as  amended  by the Prior  Amendments,  and
substituting in lieu thereof the following:

         Such   earned   royalties   shall   be   paid   (i)  at  the   rate  of
         [xxxxxxxxxxxxxxxxx]  with  respect  to  Licensed  Products  other  than
         Licensed  Combination  Products and [xxx] times the "proration  factor"
         with      respect      to      Licensed       Combination      Products
         [xxxxxxxxxxxxxxxxxxxxxxxxx]   of  aggregate   Sales  Value   (including
         aggregate Sales Value of Licensed  Combination  Products) of such sales
         during    each    License    Year    and    (ii)   at   the   rate   of
         [xxxxxxxxxxxxxxxxxxxxxxxxxx]  with respect to Licensed  Products  other
         than  Licensed  Combination  Products  and  [xxx]times  the  "proration
         factor" with respect to Licensed  Combination Products on the aggregate
         Sales Value  (including  aggregate Sales Value of Licensed  Combination
         Products) of all such sales  [xxxxxxxxxxxxxxxxxx]in  each License Year;
         provided  that no royalties  shall be paid under any  circumstances  on
         Licensed Products or Licensed Combination Products sold or manufactured
         in the United  States  following  the date of  expiration of the Biogen
         Patent, i.e., July 23, 2002 (the "Patent Expiration Date"); except that

                  (A) After the Patent  Expiration  Date and through the Royalty
                  Termination   Date,  in   consideration   of  the  assignments
                  described  in Sections 3.1 and 3.2 above,  royalties  shall be
                  paid (I) with respect to Licensed  Products sold in the United
                  States during the periods  specified below other than Licensed
                  Combination Products, at the royalty rates specified below and
                  (ii) with respect to Licensed Combination Products sold in the
                  United  States  during  such  periods  at  the  royalty  rates
                  specified below times the "proration factor"
<PAGE>


                                                                 Royalty Rate
                                                                (Percent of
                           Royalty Period                        Sales Value)

                           After the Patent Expiration               [xxx]
                           Date until July 22, 2003

                           On or after July 23, 2003                 [xxx]
                           until July 22, 2004

                           On or after July 23, 2004                 [xxx]
                           until July 22, 2005

                           On or after July 23, 2005                 [xxx]
                           until July 22, 2006

                           On or after July 23, 2006                 [xxx]
                           until July 22, 2007

                           On or after July 23, 2007 and             [xxx]
                           until the Royalty Termination
                           Date

                  ; and

                  (B) After the Patent Expiration Date, with respect to Licensed
                  Products and Licensed Combination Products manufactured in the
                  United  States and sold outside the United  States,  royalties
                  shall be paid if and only to the extent that Biogen still owns
                  an unexpired  patent or supplementary  protection  certificate
                  covering  such  Licensed  Products  or  Licensed   Combination
                  Products  in the  country in which such  Licensed  Products or
                  Licensed  Combination  Products are sold.  Any such  royalties
                  shall  be paid (i) at the  rate of  [xxxx  xxxxxxxxxxxx]  with
                  respect to Licensed  Products other than Licensed  Combination
                  Products and [xxx] times the  "proration  factor" with respect
                  to    Licensed    Combination    Products    on   such   sales
                  [xxxxxxxxxxxxxxxx   xxxxxxxx]   of   aggregate   Sales   Value
                  (including  aggregate  Sales  Value  of  Licensed  Combination
                  Products) of sales during each License  Year;  and (ii) at the
                  rate of  [xxxxxxxxxxxxxxxxxxxxxx]  with  respect  to  Licensed
                  Products and [xxx] times the  "proration  factor" with respect
                  to  Licensed  Combination  Products  on such sales  within the
                  aggregate  Sales  Value  (including  aggregate  Sales Value of
                  Licensed  Combination  Products) of all sales  [xxxxxxxxxxxxxx
                  xxxxx] in each License Year.


<PAGE>

         For purposes of the foregoing subsections (A) and (B), the Roche Patent
         Rights  shall be deemed  to be a "patent  with  respect  to any  Biogen
         Invention" under Section 1. 14(a)(i) of this Schering-Biogen Agreement.


         5.2.[xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx].

         6.    Consents and Approvals; Cooperation.

         6.1.   Schering  and  Biogen  shall  in  good  faith  cooperate  to
obtain  all Governmental  Approvals.  Both parties  agree to: (i) take  promptly
all actions necessary  to make the  filings  required  of the  parties;  (ii)
comply at the earliest practicable date with any requests for additional
information received either by Biogen or Schering from a governmental authority;
and (iii) furnish to each other such  information  and  assistance as may
reasonably be requested in connection with the foregoing,  to the extent
permissible under law. Biogen and Schering  agree to provide the other with
copies of all  correspondence  between either of them (or their advisors) and
any government  antitrust entity relating to this Biogen  Amendment,  the
Fourth Amendment or the Settlement  Agreement to the extent  permissible  under
law.  Biogen and Schering agree that all meetings with a governmental  authority
relating to any matters described in this Section 6.1 shall include
representatives of both Biogen and Schering unless Biogen and Schering jointly
decide otherwise or the governmental  authority objects to such attendance.

         6.2.  Nothing in this Biogen  Amendment  shall require Biogen or
Schering,  as a consequence of any government action or threatened  action,  to
change,  modify, add, or delete any material term in this Biogen Amendment,  or
to take any other action that shall have a material adverse effect on such
party. Either party may provide notice to the other party that it concludes, in
good faith, it would not be feasible and  consistent  with the intentions of the
parties in entering into this Biogen Amendment to continue the  effectiveness of
this Biogen Amendment in the event any governmental agency seeks to enjoin or a
court enjoins the parties from acting pursuant to this Biogen Amendment or a
governmental  authority seeks to terminate this Biogen Amendment. Upon the
receipt of such notice by the other party, this Biogen Amendment shall be

<PAGE>

declared null and void ab initio and the Biogen-Schering  Agreement shall remain
in full force and effect as if this Biogen  Amendment and Patent  Assignment had
never been  executed,  and  Schering  shall  execute an  assignment  in mutually
satisfactory form assigning the Weissmann Application to Biogen.

         7.  Confidentiality.  No party  shall make any public  statements  with
respect to this Biogen Amendment or the transactions or agreements  contemplated
hereby,  the Fourth Amendment,  the Interference,  the Interference  Appeal, the
Settlement Agreement,  nor shall any of the parties hereto disclose to any third
party  the  terms  of  this  Biogen  Amendment  or any of the  other  agreements
referenced in this Section 7, or the relationships  created hereby,  without, in
any such case, the prior written consent of the other parties hereto,  except as
required by law or  regulation.  Each party may make a press release  concerning
this  Biogen  Agreement  or the  Settlement  Agreement,  but agree that prior to
making such release,  such party will submit the text thereof to the other party
and shall issue the release only with the approval of such party, which approval
shall not be unreasonably  withheld;  provided,  that, once information has been
released in accordance  with this Section 7, the  information  contained in such
release may  subsequently  be released by the releasing  party without the prior
approval or consent of the other party.

         8.  Revocation.  In addition to those rights specified in Paragraph 6.2
above, this Biogen Amendment and the Patent  Assignment (if executed),  shall be
null and void ab initio,  and Schering  shall  execute an assignment in mutually
satisfactory form assigning the Weissmann  Application to Biogen and the present
Biogen-Schering Agreement (prior to this Biogen Amendment), shall remain in full
force and  effect as if this  Biogen  Amendment  and the Patent  Assignment  (if
executed)  had never been  executed,  if (i) either a stay of  litigation in the
Interference Appeal agreed to by the parties in the Settlement  Agreement is not
granted by the court or is lifted by the court prior to the  termination  of the
Interference Appeal by Schering,  as assignee of Biogen, under the provisions of
Paragraph  3 of the  Settlement  Agreement;  (ii) the  Settlement  Agreement  is
properly  declared  null and void ab initio or a  governmental  authority  whose
prior  approval must be obtained,  enjoins,  rejects or rescinds the  Settlement
Agreement,  the Fourth Amendment, or this Biogen Amendment or otherwise fails to
render a final approval on or before  December 31, 1998; or (iii) Roche fails to
enter into the Fourth Amendment.

         9. Covenants of Biogen.  Section 12.1 of the Biogen-Schering  Agreement
shall apply to the  prosecution  of  Additional  Patent  Rights.  In addition,
Biogen  hereby  covenants  and agrees  that it shall (i) keep  Schering  fully
informed of all actions

<PAGE>

taken with respect to the Additional Patent Rights,  and (ii) provide Schering
with copies of all  proposed  filings and  correspondence  with respect to the
Additional  Patent  Rights at least thirty (30) days before  submission to the
relevant patent office, and give good faith  consideration to any comments and
suggestions of Schering with respect  thereto.  Any and all costs and expenses
incurred  by  Biogen in  connection  with any such  actions  shall be borne by
Biogen.

         10.      Miscellaneous.

         10.1.  This Biogen  Amendment  shall  constitute  an  amendment  of the
  Biogen-Schering Agreement within the meaning of Section 18 thereof.

         10.2. Except as expressly set forth herein,  all of the other terms and
  conditions  of the  Biogen-Schering  Agreement  shall remain in full force and
  effect.

         10.3. In the event of any  inconsistency  between this Biogen Amendment
  and the Biogen  Agreement  (as  previously  amended),  the  provisions of this
  Biogen Amendment shall govern.

         IN WITNESS WHEREOF, the parties have caused this Biogen Amendment to be
executed by their  respective  officers  hereunto duly authorized as of the date
and year first written above.


                                    SCHERING  CORPORATION


                                    By:  /s/Thomas C. Lauda
                                    Name:  Thomas C. Lauda
                                    Title: Vice President


                                    BIOGEN, INC.


                                    By:   /s/James R. Tobin
                                    Name:   James R. Tobin
                                    Title:  President & Chief Executive Officer











<PAGE>



                                                                      EXHIBIT A

                           Assignment of Patent Rights

         ASSIGNMENT OF PATENT RIGHTS, dated as of May _, 1998 from Biogen, Inc.,
a Massachusetts  corporation ("Biogen"),  to Schering Corporation,  a New Jersey
corporation ("Schering").

                                   WITNESSETH

         WHEREAS,  Biogen  and  Schering  have  entered  into an  Agreement  and
Amendment  dated as of even date hereof (the  "Biogen  Amendment"),  pursuant to
which Biogen has agreed to transfer  certain  patent rights to Schering upon the
receipt of certain governmental approvals and consents and observance of certain
waiting periods specified therein ("Governmental Approvals") in exchange for the
payment by Schering of certain royalties specified therein.

         NOW, THEREFORE, in consideration of the premises and in satisfaction of
its  obligation  under the  Biogen  Amendment  and for other  good and  valuable
consideration,  the  receipt,  adequacy  and  sufficiency  of  which  is  hereby
acknowledged,  Biogen  hereby  conveys,  transfers  and assigns to, and vests in
Schering  and its  successors  and  assigns,  all of Biogen's  right,  title and
interest,  in and to the patent rights  described on Schedule A attached  hereto
(the "Assigned Patent Rights").

         TO HAVE AND TO HOLD all of the  foregoing  Assigned  Patent Rights unto
Schering, its successors and assigns, to its and their own proper use forever:

         1. Biogen, for itself and its successors and assigns,  hereby covenants
that, at any time and from time to time after  delivery of this  instrument,  at
Schering's  request and expense but without further  consideration,  Biogen will
do,  execute,  acknowledge  and  deliver,  or will  cause to be done,  executed,
acknowledged  and  delivered,  all and every  such  further  acts,  conveyances,
instruments,  transfers,  assignments,  powers of  attorney  and  assurances  as
reasonably  may be required for the better  assuring,  conveying,  transferring,
confirming  and vesting in or to  Schering,  the  Assigned  Patent  Rights or to
enable  Schering,  its successors  and assigns,  to realize upon or otherwise to
enjoy the Assigned Patent Rights.

         2. This  instrument  is executed  by, and shall be binding upon Biogen,
its  successors  and  assigns,  for the uses and  purposes  above  set forth and
referred to, effective as of the date hereof.

<PAGE>

         3.Terms used herein shall have the same meaning that such  terms  have
when  used  in the  Biogen  Amendment.  In the  event  of any inconsistency
between the  provisions  hereof and the  provisions of the Biogen Amendment,
the provisions of the Biogen  Amendment  shall be  controlling.  The
representation  and  warranties  and other  terms and  conditions  of the Biogen
Amendment shall be  incorporated in and shall survive  execution and delivery of
this Assignment of Patent Rights.

        4. This  Assignment  of Patent Rights shall be governed by and construed
and enforced in accordance with the laws of the state of New Jersey.

         IN WITNESS WHEREOF,  Biogen and Schering have caused this Assignment of
Patent  Rights  to be  signed  by their  respective  authorized  officers  as an
instrument under seal, on the day and year first above written.



                                     SCHERING CORPORATION



                                     By:      __________________________
                                     Title:


                                     BIOGEN, INC.



                                     By:      ___________________________
                                     Title:





















<PAGE>



                                                                      SCHEDULE A
                             Assigned Patent Rights

         "Assigned Patent Rights" shall mean the patent application designated
as U.S. Serial No. 471,301 filed
March 2, 1983.