<PAGE>
                                          
                         MANUFACTURING AND SUPPLY AGREEMENT


     THIS MANUFACTURING AND SUPPLY AGREEMENT (the "Agreement") is entered into
as of the 15th day of October, 1998 (the "Effective Date"), by and between
GALAGEN INC., a company incorporated under the laws of the State of Delaware,
with its principal place of business at 4001 Lexington Avenue North, Arden
Hills, Minnesota 55126 USA ("GalaGen"), AND AMERICAN HOME PRODUCTS CORPORATION,
acting through its WYETH-AYERST LABORATORIES DIVISION, a company incorporated
under the laws of the State of Delaware, with its principal place of business at
555 East Lancaster Avenue, St. Davids, Pennsylvania  19087, USA
("Wyeth-Ayerst").  Both GalaGen and Wyeth-Ayerst are referred to herein
individually as a "Party" and collectively as the "Parties".

     WHEREAS,  GalaGen has developed proprietary technology with respect to
[**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION***]; and

     WHEREAS, GalaGen and Wyeth-Ayerst, pursuant to that certain Collaboration
and License Agreement entered into by the Parties on even date herewith, are
collaborating with each other to utilize GalaGen's proprietary technology to
[***CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION***] and to develop Pediatric Formula Products
and/or Other Products containing [**CONFIDENTIAL TREATMENT REQUESTED; PORTION
OMITTED FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***]; and

     WHEREAS,  Wyeth-Ayerst desires for GalaGen to manufacture and supply it
with such [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY
WITH THE SECURITIES AND EXCHANGE COMMISSION***] for use by Wyeth-Ayerst in the
Manufacture of Pediatric Formula Products and Other Products.

     NOW THEREFORE, in consideration of the foregoing premises and the mutual
promises, covenants and conditions contained in this Agreement, the Parties
agree as follows:

1.   DEFINITIONS.

     For the purposes of this Agreement, the capitalized terms hereunder shall
     have the meanings defined below:
     
     1.1  "AFFILIATE(s) shall mean, in the case of either Party, any
          corporation, joint venture, or other business entity which directly or
          indirectly controls, is controlled by, or is under common control with
          that Party.  "Control", as used in this Section 1.1, shall mean having
          the power to direct, or cause the direction of, the management and
          policies of an entity, whether through ownership of voting securities,
          by contract or otherwise. [**CONFIDENTIAL TREATMENT REQUESTED; 


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          PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
          COMMISSION***].

     1.2  "APPROVED FACILITY" shall mean each such Manufacturing facility
          referenced in the Regulatory Approvals as an approved site for the
          Manufacture of the Ingredient and such term includes all GalaGen's
          equipment, machinery and facilities used in the manufacturing, testing
          and storage of the Ingredient.     

     1.3  "BATCH" shall mean a Manufacturing run of Ingredient in an amount to
          be agreed upon in writing by the Parties during the course of the
          Collaboration.

     1.4  "CALENDAR QUARTER" shall mean the respective periods of three (3)
          consecutive calendar months ending on March 31, June 30, September 30
          or December 31, for so long as this Agreement is in effect.

     1.5  "CERTIFICATE OF ANALYSIS" shall mean a document identifying the tests
          required for Ingredient release, results of  those tests for a
          specific lot, and the release specifications, in a form agreed to by
          the Parties in writing.

     1.6  "COLLABORATION" shall mean the research and development program
          conducted jointly by the Parties under the License Agreement for the
          purpose of optimizing the production of [***CONFIDENTIAL TREATMENT
          REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES AND
          EXCHANGE COMMISSION***] and developing and obtaining Regulatory
          Approval for Pediatric Formula Products.

     1.7  "CURRENT GOOD MANUFACTURING PRACTICE" OR "CGMP" shall mean (i) the
          current standards for the manufacture of pharmaceuticals, as set forth
          in the United States Federal Food, Drug and Cosmetics Act and
          applicable regulations promulgated thereunder, as amended from time to
          time, and such standards of good manufacturing practice as are
          required by the European Union and other organizations and
          governmental agencies in countries in which the Products are intended
          to be sold, to the extent such standards are not inconsistent with
          United States cGMP.

     1.8  "FDA" shall mean the United States Food and Drug Administration.

     1.9  "FIRST COMMERCIAL SALE" shall mean, on a Product by Product basis, the
          first sale of such Product in any country of the Territory after such
          Product has been granted Regulatory Approval by the competent
          authorities in such country.

    1.10  "INGREDIENT" shall mean [***CONFIDENTIAL TREATMENT REQUESTED; PORTION
          OMITTED FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
          COMMISSION***] and are in a form(s) to be specified by Wyeth-


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          Ayerst, which form(s) are reasonably necessary to meet Wyeth-Ayerst's
          or its Affiliates' or sublicensees' needs for the production of
          Products.

    1.11  "KNOW-HOW" shall have the meaning assigned to such term in the License
          Agreement.

    1.12  "LICENSE AGREEMENT" shall mean the Collaboration and License Agreement
          which has been entered into by the Parties on even date herewith.

    1.13  "MANUFACTURE", "MANUFACTURED" OR "MANUFACTURING" shall mean all
          activities involved in the production of Ingredient to be supplied to
          Wyeth-Ayerst, its Affiliates or sublicensees under this Agreement,
          including, without limitation, the [**CONFIDENTIAL TREATMENT
          REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES AND
          EXCHANGE COMMISSION***].

    1.14  "MANUFACTURING COST" shall mean the costs for those items specified in
          Exhibit A which have been incurred by GalaGen in Manufacturing the
          Ingredient for Wyeth-Ayerst hereunder, which costs are calculated in
          accordance with generally accepted accounting principles.

    1.15  "NET SALES" shall mean proceeds from sales of Pediatric Formula
          Products by Wyeth-Ayerst, its Affiliates or sublicensees, as
          appropriate, to Third Parties, less the sum of (a) and (b) where (a)
          is a provision, determined under generally accepted accounting
          principles in the United States, for [**CONFIDENTIAL TREATMENT
          REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES AND
          EXCHANGE COMMISSION***].

          Sales of Pediatric Formula Products by and between a Party and its
          Affiliates are not sales to Third Parties and shall be excluded form
          Net Sales calculations for all purposes.
          
    1.16  "NET SELLING PRICE" shall mean, with respect to a particular Pediatric
          Formula Product, the total Net Sales of such Pediatric Formula
          Product, made during a Calendar Quarter divided by the number of units
          of such Pediatric Formula Product sold during such Calendar Quarter.
          
    1.17  "OTHER PRODUCT(S)" shall mean any product, other than Pediatric
          Formula Products, which contains Ingredient. [**CONFIDENTIAL TREATMENT
          REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES AND
          EXCHANGE COMMISSION***].
          
    1.18  "PEDIATRIC FORMULA PRODUCT(S)" shall mean any  beverage (whether
          supplied in liquid form or as a powder to be mixed with water)
          containing Ingredient for oral consumption by infants and/or children.


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<PAGE>

     1.19 "PRODUCT(S)" shall mean any Pediatric Formula Product or any Other
          Product.

     1.20 "REGULATORY APPROVAL" shall mean all authorizations by the competent
          authorities which are required for the regular marketing, promotion,
          pricing and sale of a Product in a given country or regulatory
          jurisdiction.

     1.21 "REGULATORY AUTHORITY" shall mean any national, supra-national (e.g.,
          the European Commission, the Council of the European Union, or the
          European Agency for the Evaluation of Medicinal Products), regional,
          state or local regulatory agency, department, bureau, commission,
          council or other governmental entity involved in the granting of
          Regulatory Approval for the Product(s) and/or Ingredient.

     1.22 "SPECIFICATIONS" shall mean specifications for or concerning the
          Manufacturing, testing, quality assurance and packaging of the
          Ingredient as may be agreed upon by the Parties in writing from time
          to time, PROVIDED, HOWEVER, that such Specifications shall comply with
          all applicable Regulatory Approvals for the manufacture and sale of
          Ingredients or Products.

     1.23 "THIRD PARTY(IES)" shall mean any person(s) or entity(ies) other than
          GalaGen, Wyeth-Ayerst or their Affiliates.

     1.24 "TRANSACTION AGREEMENTS" shall mean this Agreement, the License
          Agreement and the Warrant Purchase Agreement entered into by the
          Parties on even date herewith.


2.   MANUFACTURE AND SUPPLY OF INGREDIENT.

     2.1  MANUFACTURE OF INGREDIENT.  During the term and in accordance with the
          provisions of this Agreement, GalaGen shall either manufacture the
          Ingredient at GalaGen's own premises, or, upon Wyeth-Ayerst's prior
          written consent, sub-contract the Manufacture of the Ingredient to a
          Third Party sub-contractor which is acceptable to Wyeth-Ayerst and
          which shall have sufficient knowledge and expertise to carry out the
          Manufacture of the Ingredient and meet Wyeth-Ayerst's requirements for
          the Ingredient.

     2.2  SUPPLY OF WYETH-AYERST'S REQUIREMENTS.  During the term and in
          accordance with the provisions of this Agreement, GalaGen shall
          Manufacture and supply to Wyeth-Ayerst and Wyeth-Ayerst shall purchase
          from GalaGen its entire requirements of the Ingredient for use in its
          manufacture of Products.

     2.3  FORECASTS AND ORDERS.  


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<PAGE>

          2.3.1     Not less than twelve (12) months prior to its first purchase
                    of Ingredient for use in the manufacture of Products to be
                    sold to Third Parties, Wyeth-Ayerst shall provide GalaGen
                    with a written forecast (by Calendar Quarter) of the
                    quantity of Ingredient that Wyeth-Ayerst desires to have
                    delivered to it during the first twelve (12) month period of
                    Product sales.  Within  six (6) months prior to its first
                    purchase of Ingredient, Wyeth-Ayerst shall provide GalaGen
                    with an updated forecast for the first twelve (12) month
                    period (by Calendar Quarter), and by the beginning of such
                    twelve (12) month period shall provide GalaGen with an
                    updated forecast for the last three (3) Calendar Quarters of
                    such twelve (12) month period and for the Calendar Quarter
                    following immediately thereafter.  Thereafter, at least
                    ninety (90) days before the end of each subsequent Calendar
                    Quarter, Wyeth-Ayerst shall provide a written updated
                    forecast (by Calendar Quarter) in accordance with the
                    provisions of Section 2.3.2 hereof.

          2.3.2     Each successive forecast shall update the forecast
                    previously given for the last three (3) Calendar Quarters
                    covered and add a forecast for the Calendar Quarter
                    following immediately thereafter, to enable GalaGen to have
                    sufficient information to schedule its or its
                    sub-contractors' manufacturing operations to meet
                    Wyeth-Ayerst's forecasted requirements of the Ingredient. 
                    GalaGen acknowledges that such forecasts are only estimates
                    of Wyeth-Ayerst's purchase requirements of the Ingredient
                    and that Wyeth-Ayerst shall not be bound by any such
                    estimate, except that after Regulatory Approval the first
                    Calendar Quarter of each successive forecast so provided
                    shall represent a binding commitment of Wyeth-Ayerst to
                    purchase and of GalaGen to supply such forecasted quantity
                    of Ingredient in a timely manner, subject to adjustment
                    within the limits set forth in Section 2.3.4 hereof.

          2.3.3     Wyeth-Ayerst shall order and maintain reasonable inventories
                    of the Ingredient, having due regard to its current and
                    forecasted sales volumes for the Products.  Wyeth-Ayerst
                    shall issue to GalaGen firm purchase orders for each
                    delivery not later than two (2) months prior to the
                    requested delivery date.  Such purchase orders shall specify
                    the quantity of Ingredient desired, and the place(s) to
                    which and the manner and dates by which delivery is to be
                    made.  To the extent the terms of any purchase order or
                    acknowledgment thereof are inconsistent with the terms of
                    this Agreement, the terms of this Agreement shall control.

          2.3.4     The quantity of Ingredient ordered by Wyeth-Ayerst in any
                    Calendar Quarter shall not be less than seventy-five percent
                    (75%) of the quantity specified in the last binding forecast
                    provided by Wyeth-Ayerst for such Calendar Quarter. 
                    Additionally, GalaGen shall not be obligated to supply that
                    quantity of Ingredient in any Calendar Quarter that is more
                    than one hundred and twenty-five percent (125%) of the last
                    binding forecast provided by Wyeth-Ayerst for the Calendar
                    Quarter in question; PROVIDED, 


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<PAGE>

                    HOWEVER, that GalaGen shall endeavor to take all reasonable
                    steps to fill purchase orders for the Ingredient in excess
                    of such amount.

          2.3.5     All estimates shall be prepared in good faith in order to
                    facilitate GalaGen's efficient manufacture and shipment of
                    the Ingredient in compliance with this Agreement, and except
                    as set forth in Section 2.3.2 will not be binding upon
                    Wyeth-Ayerst or GalaGen in any way and Wyeth-Ayerst shall
                    not be responsible for any loss or expense of GalaGen's
                    arising from the forecast.

          2.3.6     Notwithstanding any other provision of this Agreement,
                    GalaGen in no event shall be obligated to supply
                    Wyeth-Ayerst with an amount of Ingredient that exceeds
                    seventy percent (70%) of GalaGen's total capacity for the
                    manufacture of Ingredient and all other products.  In the
                    event Wyeth-Ayerst provides GalaGen with good faith
                    forecasts that exceed such capacity, GalaGen agrees that it
                    will use its Commercially Reasonable Efforts to seek and
                    employ subcontractors, as permitted under Section 2.1
                    hereof, to manufacture such excess amounts of Ingredient on
                    commercially reasonable terms. 

     2.4  ALTERNATIVE SUPPLY.  At any time, but no later than a reasonable time
          (which shall not exceed six (6) months plus any delay associated with
          approval of the site of manufacture by a Regulatory Authority) after
          Wyeth-Ayerst's annual purchases of the Ingredient attain a level of
          fifty percent (50%) of GalaGen's total capacity for the manufacture of
          Ingredient and all other products, or if a restriction is imposed upon
          (a) Manufacturing that would prevent GalaGen from meeting its supply
          obligation hereunder or (b) exporting the Ingredient out of the
          country where it is Manufactured, then GalaGen shall use its
          Commercially Reasonable Efforts to establish a second source for
          supply of the Ingredient which second source of supply must be
          reasonably acceptable to Wyeth-Ayerst.

     2.5  STORAGE.  GalaGen shall cause, at its own expense, the maintenance of
          adequate storage accommodations, in accordance with cGMP, for the
          quantities of Ingredient being held by or on behalf of GalaGen pending
          delivery to a carrier in accordance with Article 4 of this Agreement. 

     2.6  MANUFACTURING DATE.  GalaGen shall conduct appropriate studies in
          order to maximize the shelf life of the Ingredient.  GalaGen agrees
          not to supply Ingredient which was manufactured more than three (3)
          months prior to delivery to Wyeth-Ayerst, unless otherwise approved,
          in writing, by Wyeth-Ayerst, such approval not to be unreasonably
          withheld.

     2.7  PERMITTED SUBCONTRACTORS.  GalaGen shall ensure that the permitted
          subcontractors for the Manufacture of the Ingredient have sufficient
          knowledge and expertise to carry out the Manufacture of the Ingredient
          and other subcontracted responsibilities.  In addition GalaGen shall
          ensure that (i) each such subcontractor shall be in




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<PAGE>

          compliance with cGMPs and shall be under the inspection of all
          relevant Regulatory Authorities and audited to be in compliance
          therewith, and (ii) Wyeth-Ayerst will have the right to inspect and
          audit each such subcontractor's facilities and records as provided in
          Section 3.8 hereof.


3.   TESTING AND QUALITY CONTROL.
     
     3.1  FACILITY COMPLIANCE AND RELATED MATTERS.

          3.1.1     GalaGen covenants that the Approved Facility shall be
                    in compliance with all applicable laws, rules and
                    regulations, including cGMP, at all times during the term of
                    this Agreement. GalaGen shall be responsible for all costs
                    and expenses related to the compliance of the Approved
                    Facility with such laws, rules and regulations related to
                    the Manufacture of the Ingredient in accordance with the
                    Specifications.  The Ingredient shall be Manufactured at the
                    Approved Facility and the location thereof shall not be
                    changed without Wyeth-Ayerst's written consent, which
                    consent shall not be unreasonably withheld.

          3.1.2     For so long as the Approved Facility shall be Manufacturing
                    the Ingredient, GalaGen shall perform routine audits of the
                    Approved Facility cleaning, validation and environmental
                    monitoring programs.  GalaGen shall notify Wyeth-Ayerst in
                    the event of any adverse finding during such audit, or any
                    cross contamination issue related to the Ingredient.

     3.2  SPECIFICATIONS AMENDMENTS.  The Specifications shall be amended or
          supplemented to comply with cGMPs and to comply with any applicable
          Regulatory Authority directive and may also be amended or supplemented
          (including, without limitation, for the purpose of incorporating
          improvements) from time to time.  In the event GalaGen intends to
          amend the Specifications, Wyeth-Ayerst shall receive prompt advance
          notice of any such amendments. No such amendment shall be filed with
          any applicable Regulatory Authority or otherwise become effective
          without the prior written mutual approval of Wyeth-Ayerst and GalaGen.
          In the event that, after the Parties have initially agreed upon the
          Specifications, Wyeth-Ayerst requests that the Specifications be
          amended, GalaGen shall receive prompt advance notice of any such
          amendment for the purpose of determining what, if any, impact the
          proposed amendment would have on the Manufacture of Ingredient for
          Wyeth-Ayerst hereunder and Wyeth-Ayerst shall reimburse GalaGen for
          the actual costs incurred by GalaGen (provided that such costs are
          approved in writing by Wyeth-Ayerst prior to being incurred by
          GalaGen) because such amendment requires changes to be made in the
          processes, equipment, testing procedures, or components used to
          Manufacture the Ingredient for Wyeth-Ayerst hereunder.  Such costs may
          include, without limitation, validation of new processes, equipment
          and facilities, development of testing methods and start-up 


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<PAGE>

          costs.  Any costs incurred by GalaGen in implementing an amendment of
          the Specifications under this Section 3.2 shall not be included in
          GalaGen's Manufacturing Cost.

     3.3  QUALITY CONTROL SYSTEM.  GalaGen shall maintain and shall use its
          Commercially Reasonable Efforts to cause any permitted subcontractor
          manufacturing the Ingredient or any component thereof [**CONFIDENTIAL
          TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE
          SECURITIES AND EXCHANGE COMMISSION***] to maintain a quality control
          system consistent with cGMP, as required by the Regulatory Authorities
          and applicable laws and regulations, and documentation of such quality
          control system, as amended or supplemented, shall be made available to
          Wyeth-Ayerst during inspections or audits. 

     3.4  APPROVAL FOR MANUFACTURING CHANGES; THIRD PARTY MANUFACTURING. 
          GalaGen agrees that no changes will be made to any materials,
          equipment or methods of production or testing which are specified in
          the Specifications or any Regulatory Approval by any Regulatory
          Authority for the Ingredient without Wyeth-Ayerst's prior written
          approval, which approval shall not be unreasonably withheld.  Under no
          circumstances will GalaGen contract out all or any part of the
          manufacturing of the Ingredient to a Third Party without prior written
          approval from Wyeth-Ayerst, which approval shall not be unreasonably
          withheld.

     3.5  PRODUCTION SAMPLES, BATCH RECORDS AND CERTIFICATE OF ANALYSIS. 

          3.5.1     Each Batch of the Ingredient delivered to Wyeth-Ayerst
                    hereunder will conform to the Specifications.  GalaGen shall
                    perform release testing in a manner consistent with testing
                    methods agreed upon by the Parties.  GalaGen shall provide
                    to Wyeth-Ayerst a Certificate of Analysis with each shipment
                    of the Ingredient to Wyeth-Ayerst or its designated
                    recipient stating that the Ingredient so shipped conforms to
                    the Specifications.  The Certificate of Analysis shall be in
                    a format agreed upon by the Parties.

          3.5.2     GalaGen shall retain production samples and Batch records
                    from each Batch of Ingredient for the longer of (i) five (5)
                    years after the manufacture of each such Batch of Ingredient
                    or (ii) the time period required under cGMP.  Upon request,
                    GalaGen shall provide Wyeth-Ayerst's Quality Control
                    Department with production samples of the Ingredient and/or
                    copies of completed Batch records.

          3.5.3     Master Batch process documentation will be prepared and
                    approved by GalaGen as per its normal procedures.  The
                    Parties agree that deviations from master Batch process
                    documentation may be necessary from time to time.  Such
                    deviations shall be discussed with Wyeth-Ayerst before any


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                    proposed shipment of the Ingredient.  Individual Batch
                    process documentation shall be photocopied from the approval
                    master and issued for each Batch as per GalaGen's or its
                    sub-contractor's routine system.  Original Batch records
                    will be filed securely by GalaGen or its sub-contractor.  
                    GalaGen or GalaGen's sub-contractor will perform all
                    in-process control tests demanded by the approved Batch
                    process.

     3.6  BATCH FAILURE.  GalaGen agrees to notify Wyeth-Ayerst within one (1)
          working days of discovery of any Batch failure which could result in
          GalaGen's inability to meet Wyeth-Ayerst's requested delivery dates.

     3.7  NOTIFICATION OF INSPECTIONS.  Each Party agrees to notify the other
          within [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED
          SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***] days of its
          receipt of notification of any inquiries, notifications, or inspection
          activity by any Regulatory Authority, governmental agency or authority
          in regard to or affecting the Ingredient.  The recipient Party shall
          provide a reasonable description to the other Party of any such
          governmental inquiries, notifications or inspections promptly (but in
          no event later than [**CONFIDENTIAL TREATMENT REQUESTED; PORTION
          OMITTED FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
          COMMISSION***] days) after notification of completion of such visit or
          inquiry.  The recipient Party shall furnish to the other Party, (i)
          within [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED
          SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***] days after
          receipt, any report or correspondence issued by the Regulatory
          Authority or governmental authority in connection with such visit or
          inquiry, including but not limited to, any FDA Form 483, Establishment
          Inspection Reports or warning letters and (ii) at the same time it
          provides to any Regulatory Authority or governmental authority, copies
          of any and all documents, responses or explanations relating to items
          set forth above, in each case purged only of trade secrets of the
          recipient that are unrelated to the obligations under this Agreement
          or the License Agreement or are unrelated to the Ingredient.  In the
          event such governmental agency or authority requests or requires any
          action to be taken to address any citations, the recipient agrees,
          after consultation with the other Party, to take such action as
          necessary to address such citations, and agrees to cooperate with the
          other Party with respect to any such citation and/or action taken with
          respect thereto.

     3.8  INSPECTION BY WYETH-AYERST.  GalaGen shall permit or obtain the right
          for Wyeth-Ayerst (at its own expense) to visit, during normal business
          hours and with reasonable advance notice [**CONFIDENTIAL TREATMENT
          REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES AND
          EXCHANGE COMMISSION***] GalaGen's, or its sub-contractors'
          manufacturing facility(ies) and warehouse, and the Approved Facility,
          subject to the confidentiality provisions of this Agreement, for the
          purposes of (a) observing the 


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          Manufacturing, packaging, testing and warehousing of the Ingredient
          and to inspect for compliance with cGMPs, applicable regulatory
          requirements, the requirements of any applicable Regulatory Approvals,
          and environmental monitoring, (b) solving technical or quality
          problems, (c) examining the premises, equipment, procedures and
          personnel used when producing, testing or controlling the Ingredient
          and (d) all books and records relating to (a), (b) or (c).  GalaGen
          representatives shall be entitled to accompany Wyeth-Ayerst
          representatives on any such inspection.

     3.9  ENVIRONMENTAL AND OTHER LAWS AND REGULATIONS.

          3.9.1     In carrying out its obligations under this Agreement,
                    GalaGen and/or its sub-contractor shall comply with all
                    applicable environmental, health and safety laws (current or
                    as amended or added, collectively "Laws"), and shall be
                    solely responsible for determining how to comply with same. 
                    GalaGen represents and warrants that it and/or its
                    sub-contractor(s) have the appropriate skills, personnel,
                    equipment, permits or approvals necessary to perform its
                    services under this Agreement in compliance with all
                    applicable Laws.

          3.9.2     GalaGen shall notify Wyeth-Ayerst, in writing, no later than
                    one (1) business day after the event, of any circumstances,
                    including the receipt of any notice, warning, citation,
                    finding, report or service of process, relating to
                    compliance with the Laws, or the occurrence of any release,
                    spill, upset or discharge of "Hazardous Substances" as
                    defined by the Comprehensive Environmental Response,
                    Compensation and Liability Act of 1980, as amended, which
                    relates to GalaGen's or sub-contractor's ability to
                    Manufacture or supply the Ingredient.  Wyeth-Ayerst reserves
                    the right to conduct an environmental inspection of
                    GalaGen's or its sub-contractors' facility, during normal
                    business hours and with reasonable advance notice, for the
                    purpose of determining compliance with this Section 3.9, no
                    more frequently than once per year during the term hereof
                    and under conditions of confidentiality as provided under
                    Article 10.  Upon GalaGen's request Wyeth-Ayerst shall share
                    the results of any environmental inspection with GalaGen. 
                    Such inspection, if it occurs, does not relieve GalaGen of
                    its sole obligation to comply with the Laws and does not
                    constitute a waiver of any right otherwise available to
                    Wyeth-Ayerst.

4.   DELIVERY

     4.1  DELIVERY SITES AND RISK OF LOSS.  Delivery of each order of Ingredient
          shall be D.D.P. (Incoterms, 1990) to those sites  specified by
          Wyeth-Ayerst from time to time via a carrier that is mutually
          agreeable to the Parties.  GalaGen shall pay for freight and shipping
          charges, per D.D.P., to all designated sites.  Title to and risk of
          loss of the Ingredient shall pass to Wyeth-Ayerst at the time of
          delivery by GalaGen 


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<PAGE>

          to Wyeth-Ayerst.  Wyeth-Ayerst agrees to reimburse GalaGen for
          [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY
          WITH THE SECURITIES AND EXCHANGE COMMISSION***] of the delivery costs
          incurred by GalaGen in accordance with this Section 4.1.  GalaGen
          shall promptly invoice Wyeth-Ayerst for all Ingredient tendered, which
          invoice shall set forth the purchase price payable by Wyeth-Ayerst
          pursuant to Section 6.1 hereof and Wyeth-Ayerst's share of the
          delivery costs pursuant to this Section 4.1.  Delivery costs incurred
          by GalaGen under this Section 4.1 shall not be included as part of
          GalaGen's Manufacturing Cost.

     4.2  SCHEDULING OF DELIVERY.  Subject to the provisions of Section 2.3
          hereof, GalaGen shall schedule the timely Manufacture and shipment of
          the Ingredient pursuant to Wyeth-Ayerst's firm purchase orders.

     4.3  DELAY AND FAILURE TO SUPPLY.  Should GalaGen, at any time during the
          course of this Agreement, have reason to believe that it will be
          unable to meet Wyeth-Ayerst's requested delivery dates, GalaGen will
          promptly notify Wyeth-Ayerst in writing setting forth the reasons for
          the delay.  Such notification will not be deemed a waiver of GalaGen's
          obligation set forth in Section 4.3(b).  In connection therewith: 

          (a)  If at any time GalaGen experiences a shortage of Ingredient
               supply and the available supplies of Ingredient are not
               sufficient to satisfy all of Wyeth-Ayerst's requirements for the
               Ingredient, GalaGen shall allocate its available worldwide
               supplies (including inventory in excess of customary supplies)
               first to Wyeth-Ayerst based on Wyeth-Ayerst's binding forecasts
               and any excess supplies of Ingredient may thereafter be allocated
               among its own requirements and those of its licensees and
               distributors.


          (b)  If at any time GalaGen is of the opinion that it may not be able
               to meet future binding orders from Wyeth-Ayerst for Ingredient
               (including, but not limited to a situation where as a result of
               any intellectual property litigation GalaGen chooses not to
               supply Ingredient) it shall notify Wyeth-Ayerst in writing, and
               the Parties shall in good faith cooperate and endeavor to make
               appropriate arrangements for a continuous and adequate supply of
               Ingredient from GalaGen to Wyeth-Ayerst.

     4.4  APPOINTMENT OF WYETH-AYERST AS MANUFACTURER. 

          4.4.1     Subject to terms and provisions of this Agreement,
                    including, without limitation, GalaGen's right to
                    manufacture the Ingredient for supply to Wyeth-Ayerst,
                    GalaGen hereby grants to Wyeth-Ayerst a non-exclusive,
                    perpetual, world-wide, royalty-free license to manufacture
                    the Ingredient for use by Wyeth-Ayerst in accordance with
                    the provisions of the License Agreement.  Consistent with
                    GalaGen's obligations under Section 2.3.4 if GalaGen is
                    unable to supply at least [**CONFIDENTIAL TREATMENT


                                          11
<PAGE>

                    REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE
                    SECURITIES AND EXCHANGE COMMISSION***] of the quantities of
                    Ingredient ordered by Wyeth-Ayerst in any two (2)
                    consecutive Calendar Quarters, based on Wyeth-Ayerst's good
                    faith estimates of its future requirements, Wyeth-Ayerst
                    shall be relieved of its obligation to purchase that portion
                    of its requirements of Ingredient from GalaGen that GalaGen
                    is unable to supply, until such inability to supply has
                    ceased and GalaGen may resume the manufacture of
                    Wyeth-Ayerst's requirements of the Ingredient pursuant to
                    Section 4.5 hereof, and Wyeth-Ayerst shall have the right,
                    under the license granted in this Section 4.4.1, to
                    manufacture, or have manufactured, such portion of the
                    Ingredient that GalaGen is unable to supply.  GalaGen has
                    the right to approve, in advance, any Third Party
                    manufacturer utilized by Wyeth-Ayerst pursuant to this
                    Section 4.4.1, PROVIDED, HOWEVER, that  GalaGen's approval
                    shall not be unreasonably withheld and shall be communicated
                    to Wyeth-Ayerst within ten (10) days of notice from
                    Wyeth-Ayerst to GalaGen.  If the quantity of Ingredient that
                    GalaGen is unable to supply is so limited that it would be
                    an excessive financial burden on Wyeth-Ayerst to
                    manufacture, or have manufactured, such limited quantity,
                    the Parties shall meet, after GalaGen is notified by
                    Wyeth-Ayerst of such circumstance, and in good faith seek to
                    reasonably resolve the matter.  For purposes of this Section
                    4.4.1, the provision of such Ingredient to Wyeth-Ayerst by
                    [***CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED
                    SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***]
                    or any permitted subcontractor of GalaGen or
                    [***CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED
                    SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***]
                    shall be deemed for purposes of determining whether
                    Wyeth-Ayerst may exercise its right to manufacture
                    Ingredient hereunder to be the provision of such Ingredient
                    by GalaGen.  Notwithstanding any other provision hereof, if
                    GalaGen's failure to supply Ingredient is attributable
                    solely to its inability to [**CONFIDENTIAL TREATMENT
                    REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE
                    SECURITIES AND EXCHANGE COMMISSION***] otherwise complete
                    the manufacture of Ingredient and its not attributable, in
                    whole or in part, to its inability to [**CONFIDENTIAL
                    TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION***], Wyeth-Ayerst
                    shall not [**CONFIDENTIAL TREATMENT REQUESTED; PORTION
                    OMITTED FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
                    COMMISSION***] and GalaGen shall continue to have the right
                    to be Wyeth-Ayerst's supplier of [**CONFIDENTIAL TREATMENT
                    REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE
                    SECURITIES AND EXCHANGE COMMISSION***] pursuant to the terms
                    and conditions of this 


                                          12
<PAGE>

                    Agreement, including, without limitation, the purchase price
                    provisions of Section 6.1 (PROVIDED, HOWEVER, that in such
                    event the calculation of GalaGen's Manufacturing Cost shall
                    be based only on [**CONFIDENTIAL TREATMENT REQUESTED;
                    PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES AND
                    EXCHANGE COMMISSION***]).  Notwithstanding the foregoing, in
                    the event GalaGen is continuing to supply Ingredient to
                    Wyeth-Ayerst as provided herein, Wyeth-Ayerst shall have the
                    right to [**CONFIDENTIAL TREATMENT REQUESTED; PORTION
                    OMITTED FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
                    COMMISSION***] if, for two successive calendar quarters,
                    GalaGen's inventories of [**CONFIDENTIAL TREATMENT
                    REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE
                    SECURITIES AND EXCHANGE COMMISSION***] fall below the amount
                    of [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED
                    FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
                    COMMISSION***] needed to manufacture Wyeth-Ayerst's
                    forecasted needs (as provided in its most recent binding
                    forecasts pursuant to Section 2.3) of Ingredient.

          4.4.2     In the event that GalaGen is unable to supply Ingredient as
                    provided above, GalaGen shall be responsible for all costs
                    to qualify Wyeth-Ayerst, or its designated manufacturer, as
                    a manufacturer of the Ingredient.  Such costs include, but
                    are not limited to, [**CONFIDENTIAL TREATMENT REQUESTED;
                    PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES AND
                    EXCHANGE COMMISSION***]. 

     4.5  RESUMPTION OF MANUFACTURING BY GALAGEN.  At such time as GalaGen
          reasonably demonstrates to Wyeth-Ayerst that it is able to again
          supply all of Wyeth-Ayerst's requirements on an ongoing basis,
          Wyeth-Ayerst shall be permitted to continue to manufacture, or have
          manufactured that amount of Ingredient it had been manufacturing
          pursuant to Section 4.4 hereof, for such period of time thereafter as
          is reasonably necessary for Wyeth-Ayerst and/or any of its Affiliates
          and/or any Third Party manufacturer to fully amortize all expenses
          that may have been reasonably incurred under such manufacturing
          program, using generally accepted accounting principles normally used
          by Wyeth-Ayerst in keeping its own books and records.  Thereafter,
          Wyeth-Ayerst shall purchase its requirements of Ingredient from
          GalaGen in accordance with the terms of this Agreement, PROVIDED,
          HOWEVER, that Wyeth-Ayerst shall be permitted to continue
          manufacturing or purchasing from such Third Party(ies) Ingredient in
          amounts equal to the greater of (i) the amount of Wyeth's requirements
          of Ingredient that GalaGen is currently unable to supply or (ii)
          [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY
          WITH THE SECURITIES AND EXCHANGE COMMISSION***] of Wyeth's
          requirements of Ingredient that Wyeth-Ayerst has manufactured or has
          purchased from Third Parties [**CONFIDENTIAL 




                                          13
<PAGE>

          TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE
          SECURITIES AND EXCHANGE COMMISSION***].

     4.6  DISCLOSURE OF GALAGEN KNOW-HOW; TECHNICAL ASSISTANCE.  If, pursuant to
          Sections 4.4 or 4.5 hereof, Wyeth-Ayerst elects to commence
          manufacturing the Ingredient, either itself or through a Third Party,
          GalaGen shall promptly disclose to Wyeth-Ayerst all of its Know-How
          that is necessary to enable Wyeth-Ayerst to so manufacture the
          Ingredient to the extent permitted hereunder.  Additionally, GalaGen
          shall, at no cost to Wyeth-Ayerst, provide Wyeth-Ayerst with
          reasonable technical assistance that may be necessary or useful for
          Wyeth-Ayerst to utilize such Know-How and to commence the manufacture
          of the Ingredient to the extent permitted hereunder.  If GalaGen
          discloses Know-How to Wyeth-Ayerst for the purpose of enabling
          Wyeth-Ayerst or its designee to manufacture Ingredient, Wyeth-Ayerst
          agrees to use such Know-How only for such purpose and such Know-How
          shall be treated as Confidential Information in accordance with
          Article 10 hereof.

     4.7  QUALITY ASSURANCE.

          4.7.1     Prior to the shipment of Ingredient to Wyeth-Ayerst, GalaGen
                    shall test representative samples of each of the lot(s) to
                    be shipped in accordance with the methods of analysis
                    defined in the Specifications.  GalaGen shall provide
                    Wyeth-Ayerst with a certificate of analysis for each lot of
                    Ingredient shipped to Wyeth-Ayerst.

          4.7.2     Wyeth-Ayerst shall have the right to test Ingredient to
                    verify compliance with Specifications and applicable
                    Regulatory Approvals and GalaGen shall supply Wyeth-Ayerst
                    with its testing procedures.  Wyeth-Ayerst may, by written
                    notice provided to GalaGen within [**CONFIDENTIAL TREATMENT
                    REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE
                    SECURITIES AND EXCHANGE COMMISSION***] of Wyeth-Ayerst's
                    receipt of a shipment of Ingredient, reject all or part of
                    such shipment of Ingredient if, based upon the testing of
                    such Ingredient conducted under this Section 4.7, such
                    Ingredient does not comply with the Specifications.  If
                    Wyeth-Ayerst fails to notify GalaGen, within such
                    [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED
                    SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***]
                    period, that it is rejecting such Ingredient, Wyeth-Ayerst
                    shall be deemed to have accepted such Ingredient.

          4.7.3     If GalaGen, after good faith consultation with Wyeth-Ayerst,
                    disputes any finding by Wyeth-Ayerst that the Ingredient
                    does not comply with the Specifications, samples of such
                    Ingredient shall be forwarded to a Third Party jointly
                    selected by Wyeth-Ayerst and GalaGen for analysis, which
                    analysis shall be performed in compliance with applicable
                    regulatory 


                                          14
<PAGE>

                    requirements.  The findings of such Third Party regarding
                    whether the Ingredient complies with the Specifications and
                    the applicable Regulatory Approvals shall be binding upon
                    the Parties for purposes of this Section 4.7.  The cost of
                    such analysis by such Third Party shall be borne by the
                    Party whose findings differed from those generated by such
                    Third Party.

          4.7.4     If, as determined in accordance with this Section 4.7, a
                    shipment of Ingredient does not conform to the
                    Specifications, GalaGen shall replace such shipment free of
                    charge with a substitute shipment which meets such
                    Specifications according to the following time frame:  If
                    the Ingredient is in inventory then conforming Ingredient
                    will be shipped so as to arrive as soon as practicable.  If
                    the Ingredient is not in inventory, GalaGen will take all
                    reasonable steps to ensure expeditious Manufacture of
                    conforming Ingredient which will be shipped on the next
                    shipping day after completion of Manufacture so as to arrive
                    as soon as possible thereafter.  In the event that testing
                    at Wyeth-Ayerst indicates that Ingredient does not conform
                    with Specifications: (i) Wyeth-Ayerst shall immediately
                    notify GalaGen; (ii) Wyeth-Ayerst and GalaGen shall mutually
                    agree on an investigation program to determine the cause of
                    the discrepancy and the outcome of this investigation shall
                    be used to determine disposition of the Batch; (iii) where
                    appropriate, given the timetable for the agreed
                    investigation program, GalaGen shall take all reasonable
                    steps to ensure expeditious Manufacture and shipment of
                    conforming Ingredient; and (iv) shipment of such replacement
                    Ingredient shall take place the next shipping day following
                    completion of analytical work to demonstrate conformance
                    with Specifications. Shipment shall be by the quickest
                    agreed route.  At GalaGen's expense and at Wyeth-Ayerst's
                    sole option: (i) the non-conforming shipment shall be
                    returned to GalaGen; or (ii) disposed of by Wyeth-Ayerst,
                    upon final determination in accordance with this Section 4.7
                    that it does not meet the Specifications.


5.   RECALLS

     5.1  NOTIFICATION AND RECALL.

          5.1.1     In the event that any governmental agency or authority
                    requests a recall or takes similar action in connection with
                    the Ingredient or with the Product because of or in
                    connection with the presence of the Ingredient therein, or
                    in the event either Party determines an event, incident or
                    circumstance has occurred which may result in the need for a
                    recall or market withdrawal, the Party notified of or
                    calling such recall or similar action shall, within
                    [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED
                    SEPARATELY WITH THE SECURITIES AND 


                                          15
<PAGE>

                    EXCHANGE COMMISSION***], advise the other Party by telephone
                    or facsimile.

          5.1.2     Following notification of a recall, within [**CONFIDENTIAL
                    TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY WITH
                    THE SECURITIES AND EXCHANGE COMMISSION***], the Parties'
                    representatives from business, medical, regulatory, quality
                    assurance and legal functions (and any others deemed
                    necessary by a Party) (the "Recall Team") shall discuss
                    whether or not to conduct a recall, and, if so, the timing
                    of the recall, the breadth, extent and level of customer to
                    which the recall shall reach, what strategies and
                    notifications should be used, the responsibility for the
                    recall expenses, etc.  In the event the Recall Team cannot
                    agree on such decisions, the issues shall be resolved by
                    [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED
                    SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***]. 
                    In the event such [**CONFIDENTIAL TREATMENT REQUESTED;
                    PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES AND
                    EXCHANGE COMMISSION***] cannot agree, Wyeth-Ayerst shall
                    have the final authority to decide whether a recall of the
                    Product shall be made.  

          5.2  RECALL EXPENSES.  Wyeth-Ayerst shall bear the expenses of any
               recall resulting from breach of its obligations hereunder or
               under the License Agreement, from negligent manufacturing,
               packaging, storage, shipment, marketing, distribution or sale of
               the Product by Wyeth-Ayerst or from any manufacturing defect in a
               Product manufactured or sold by Wyeth-Ayerst which manufacturing
               defect is not a defect in the Ingredient Manufactured or supplied
               by or on behalf of GalaGen or its permitted subcontractors
               hereunder.  GalaGen shall bear the expenses of any recall
               resulting from a breach of its obligations hereunder or under the
               License Agreement, from negligent Manufacturing, packaging,
               storage, shipment, marketing, distribution or sale of the
               Ingredient by GalaGen or from any Manufacturing defect in the
               Ingredient.  The Parties shall equally divide the costs of any
               recall resulting from a latent defect (for example, side effects
               of the Ingredient not known by the Parties as of the Effective
               Date).  For the purposes of this Agreement, expenses of recall
               include, without limitation, the expenses incurred by the
               affected Party for the investigation, notification, regulatory
               reporting and/or destruction or return of the recalled Ingredient
               or Product, the sum paid by Wyeth-Ayerst to GalaGen for the
               Ingredients recalled, Wyeth-Ayerst's costs relating to the
               manufacturing, testing, packaging, shipping and supplying the
               Products recalled.


                                          16
<PAGE>

6.   CONSIDERATION

     6.1  PRICE. [***CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED
          SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***]

     6.2  METHOD OF PAYMENT.  GalaGen will invoice Wyeth-Ayerst in United States
          Dollars for each and every shipment of Ingredient accepted by
          Wyeth-Ayerst.  Each such invoice shall be accompanied by a statement
          specifying the amount of Ingredient delivered to Wyeth-Ayerst, the
          total  Manufacturing Cost incurred in manufacturing such Ingredient,
          and an itemization by category of the cost for each element included
          within the  Manufacturing Cost.  Payment for all such quantities so
          shipped shall be made in United States dollars by check or bank
          transfer within [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED
          FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***] of
          the date the invoice is received by Wyeth-Ayerst.

     6.3  TAXES.  GalaGen and Wyeth-Ayerst agree to cooperate reasonably with
          each other in connection with the tax (including value-added tax) or
          duty-free importation and/or exportation of the Ingredient, whenever
          such tax or duty-free treatment is appropriate under the applicable
          tax and customs laws and regulations.

     6.4  RECORD KEEPING.  GalaGen shall keep accurate books and accounts of
          record in connection with its Manufacture of the Ingredient in
          sufficient detail to permit accurate determination of all figures
          necessary for verification of Manufacturing Cost incurred by GalaGen
          in the Manufacture of the Ingredient hereunder.  GalaGen shall
          maintain such records for a period of [**CONFIDENTIAL TREATMENT
          REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES AND
          EXCHANGE COMMISSION***] after the end of the year in which they were
          generated.

     6.5  AUDIT BY WYETH-AYERST.  Wyeth-Ayerst, through an independent certified
          public accountant reasonably acceptable to GalaGen, shall have the
          right, at its own expense, to access the books and records of GalaGen
          for the sole purpose of verifying the statements furnished by GalaGen
          pursuant to Section 6.2.  Such access shall be conducted after
          reasonable prior written notice to GalaGen and during ordinary
          business hours and shall not be more frequent than twice per calendar
          year.  Wyeth-Ayerst agrees to keep in strict confidence all
          information learned in the course of such audit, except when it is
          necessary to reveal such information in order to enforce its rights
          under this Agreement.  Wyeth-Ayerst's right to have such records
          examined shall survive termination or expiration of this Agreement. 
          In the event such audit reveals an overpayment GalaGen shall promptly
          refund to Wyeth-Ayerst the amount of such overpayment.  In the event
          such audit reveals an overpayment of [**CONFIDENTIAL TREATMENT
          REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE 


                                          17
<PAGE>

          SECURITIES AND EXCHANGE COMMISSION***] or more of the amount actually
          due, GalaGen shall also promptly reimburse Wyeth-Ayerst for the costs
          of such audit.

     6.6  [***CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY
          WITH THE SECURITIES AND EXCHANGE COMMISSION***]
          

7.   REPRESENTATIONS AND WARRANTIES.

     7.1  REPRESENTATIONS AND WARRANTIES OF EACH PARTY.  Each of GalaGen and
          Wyeth-Ayerst hereby represents, warrants and covenants to the other
          Party hereto as follows:

          (a)  it is a corporation or entity duly organized and validly existing
               under the laws of the state or other jurisdiction of
               incorporation or formation;

          (b)  the execution, delivery and performance of this Agreement by such
               Party has been duly authorized by all requisite corporate action
               and do not require any shareholder action or approval;
 
          (c)  it has the power and authority to execute and deliver this
               Agreement and to perform its obligations hereunder;

          (d)  the execution, delivery and performance by such Party of this
               Agreement and its compliance with the terms and provisions hereof
               does not and will not conflict with or result in a breach of any
               of the terms and provisions of or constitute a default under (i)
               a loan agreement, guaranty, financing agreement, agreement
               affecting a product or other agreement or instrument binding or
               affecting it or its property; (ii) the provisions of its charter
               or operative documents or bylaws; or (iii) any order, writ,
               injunction or decree of any court or governmental authority
               entered against it or by which any of its property is bound; and

          (e)  it shall comply with all applicable material laws and regulations
               relating to its activities under this Agreement.


     7.2  REPRESENTATIONS AND WARRANTIES OF GALAGEN.  In addition to the
          representations and warranties made by GalaGen under Section 7.1
          above, GalaGen hereby further represents and warrants to Wyeth-Ayerst
          that:

          (a)  at the time of delivery of the Ingredient to the specified point
               of delivery, the Ingredient shall (i) have been Manufactured,
               stored and shipped in accordance with cGMPs, as applicable, and
               all other applicable laws, rules, 


                                          18
<PAGE>

               regulations or requirements in effect at the time of Manufacture
               in the country of Manufacture (for example, in accordance with
               the procedures described in the applicable Regulatory Approval);
               (ii) conform to the Specifications; (iii) meet the provisions of
               the Specifications; (iv) shall not be adulterated or misbranded
               as provided for under any applicable law, order or regulation in
               effect in the country of Manufacture and the country in which the
               Product is being sold pursuant to the License Agreement; (v)
               shall have been Manufactured and have shelf-life in accordance
               with the provisions of Section 2.6; and (vi) have been shipped in
               accordance with approved procedures agreed between Wyeth-Ayerst
               and GalaGen;

          (b)  it shall have good and marketable title to all Ingredient
               delivered to Wyeth-Ayerst;

          (c)  to the best of its knowledge the Manufacture, use and sale of the
               Ingredient supplied to Wyeth-Ayerst under this Agreement do not
               infringe any intellectual property rights of any Third Party or
               in any country where such Ingredient or Product is manufactured
               or sold.

     7.3  NO INCONSISTENT AGREEMENTS.  Except as otherwise provided in Sections
          11.3 and 11.4  of the License Agreements, neither Party has in effect
          and after the Effective Date neither Party shall enter into any oral
          or written agreement or arrangement that would be inconsistent with
          its obligations under this Agreement.
     
     7.4  REPRESENTATION BY LEGAL COUNSEL.  Each Party hereto represents that it
          has been represented by legal counsel in connection with this
          Agreement and acknowledges that it has participated in the drafting
          hereof.  In interpreting and applying the terms and provisions of this
          Agreement, the Parties agree that no presumption shall exist or be
          implied against the Party which drafted such terms and provisions.


8.   INDEMNIFICATION AND INSURANCE

     8.1  INDEMNIFICATION BY WYETH-AYERST.  Wyeth-Ayerst shall indemnify, defend
          and hold harmless GalaGen and its Affiliates, and each of its and
          their respective employees, officers, directors and agents (each, a
          "GalaGen Indemnified Party") from and against any and all liability,
          loss, damage, cost, and expense (including reasonable attorneys' fees)
          (collectively, a "Liability") which the GalaGen Indemnified Party may
          incur, suffer or be required to pay resulting from or arising in
          connection with (i) the breach by Wyeth-Ayerst of any covenant,
          representation or warranty contained in this Agreement, (ii) the
          manufacture, promotion, distribution, use, testing, marketing, sale or
          other disposition of Products by Wyeth-Ayerst, its Affiliates or
          sublicensees, or (iii) the successful enforcement by a GalaGen
          Indemnified Party of its rights under this Section 8.1. 
          Notwithstanding 


                                          19
<PAGE>

          the foregoing, Wyeth-Ayerst shall have no obligation under this
          Agreement to indemnify, defend or hold harmless any GalaGen
          Indemnified Party with respect to claims, demands, costs or judgments
          which result from willful misconduct or negligent acts or omissions of
          GalaGen, its Affiliates, or any of their respective employees,
          officers, directors or agents.

     8.2  INDEMNIFICATION BY GALAGEN.  GalaGen shall indemnify, defend and hold
          harmless Wyeth-Ayerst and its Affiliates, and each of its and their
          respective employees, officers, directors and agents (each, a
          "Wyeth-Ayerst Indemnified Party") from and against any Liability which
          the Wyeth-Ayerst Indemnified Party may incur, suffer or be required to
          pay resulting from or arising in connection with (i) the breach by
          GalaGen of any covenant, representation or warranty contained in this
          Agreement; (ii) the discovery, development, manufacture, promotion,
          sale or use of the Ingredient by GalaGen, its Affiliates or their
          subcontractors; or (iii) the successful enforcement by a Wyeth-Ayerst
          Indemnified Party of its rights under this Section 8.2. 
          Notwithstanding the foregoing, GalaGen shall have no obligation under
          this Agreement to indemnify, defend, or hold harmless any Wyeth-Ayerst
          Indemnified Party with respect to claims, demands, costs or judgments
          which result from willful misconduct or negligent acts or omissions of
          Wyeth-Ayerst, its Affiliates, or any of their respective employees,
          officers, directors or agents.

     8.3  CONDITIONS TO INDEMNIFICATION.  The obligations of the indemnifying
          Party under Sections 8.1 and 8.2 are conditioned upon the delivery of
          written notice to the indemnifying Party of any potential Liability
          promptly after the indemnified Party becomes aware of such potential
          Liability.  The indemnifying Party shall have the right to assume the
          defense of any suit or claim related to the Liability if it has
          assumed responsibility for the suit or claim in writing; however, if
          in the reasonable judgment of the indemnified Party, such suit or
          claim involves an issue or matter which could have a materially
          adverse effect on the business operations or assets of the indemnified
          Party, the indemnified Party may waive its rights to indemnity under
          this Agreement and control the defense or settlement thereof, but in
          no event shall any such waiver be construed as a waiver of any
          indemnification rights such Party may have at law or in equity.  If
          the indemnifying Party defends the suit or claim, the indemnified
          Party may participate in (but not control) the defense thereof at its
          sole cost and expense.

     8.4  SETTLEMENTS.  Neither Party may settle a claim or action related to a
          Liability without the consent of the other Party, if such settlement
          would impose any monetary obligation on the other Party or require the
          other Party to submit to an injunction or otherwise limit the other
          Party's rights under this Agreement.  Any payment made by a Party to
          settle any such claim or action shall be at its own cost and expense.


                                          20
<PAGE>

     8.5  INSURANCE.   Each Party further agrees to use reasonable commercial
          efforts to obtain and maintain, during the term of this Agreement,
          Comprehensive General Liability Insurance, including Products
          Liability Insurance, with reputable and financially secure insurance
          carriers to cover its indemnification obligations under Sections 8.1
          or 8.2, as applicable, or, in the case of Wyeth-Ayerst,
          self-insurance, in each case with limits of not less than
          [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY
          WITH THE SECURITIES AND EXCHANGE COMMISSION***].


9.   TERM AND TERMINATION.

     9.1  TERM. This Agreement shall be effective as of the Effective Date and
          unless terminated earlier by mutual written agreement of the Parties
          or pursuant to Sections 9.2 or 9.3 below, the Term of this Agreement
          shall continue in effect until the later of (i) the expiration of the
          License Agreement or (ii) fifteen (15) years after the First
          Commercial Sale of a Product (the "Initial Term").  The term of this
          Agreement may be extended [**CONFIDENTIAL TREATMENT REQUESTED; PORTION
          OMITTED FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
          COMMISSION***] (each a "Renewal Term") at Wyeth-Ayerst's option by
          providing GalaGen with written notice of such extension at least three
          (3) months prior to the expiration of the Initial Term or any Renewal
          Term, as applicable.  Notwithstanding the foregoing, in the event that
          GalaGen is able to reasonably demonstrate that the continued
          manufacture and supply to Wyeth-Ayerst of Ingredient during any such
          Renewal Term would not be commercially feasible for GalaGen, then
          GalaGen may elect not to so extend the term of this Agreement,
          PROVIDED, HOWEVER, that GalaGen must notify Wyeth-Ayerst, in writing,
          of such election no later than thirty (30) days after receiving from
          Wyeth-Ayerst notice that Wyeth-Ayerst has elected to extend the term, 
          which notice shall set forth those facts and be accompanied by that
          supporting documentation that is necessary to demonstrate that the
          continued Manufacture and supply of Ingredient to Wyeth-Ayerst would
          not be commercially feasible to GalaGen and provided further that
          after providing such notice to Wyeth-Ayerst (a) Wyeth-Ayerst may
          exercise its right, under the license granted in the first sentence of
          Section 4.4.1, to manufacture, either itself or through a Third Party,
          Ingredient and (b) GalaGen shall (i) in accordance with Section 4.6
          hereof, promptly disclose to Wyeth-Ayerst all Know-How and information
          necessary for Wyeth-Ayerst, its Affiliates or subcontractors to
          manufacture Ingredient, (ii) provide reasonable technical assistance,
          at GalaGen's expense, that may be necessary for Wyeth-Ayerst, its
          Affiliates or subcontractors to manufacture the Ingredient and (iii)
          continue to Manufacture and supply Ingredient to Wyeth-Ayerst, under
          the terms of this Agreement, until the earlier of (x) the time that
          Wyeth-Ayerst, its Affiliates or subcontractors are producing
          Wyeth-Ayerst's requirements of the Ingredient or (y) [**CONFIDENTIAL
          TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY 


                                          21
<PAGE>

          WITH THE SECURITIES AND EXCHANGE COMMISSION***] after the expiration
          of the applicable Initial Term or Renewal Term of this Agreement.
          
     9.2  TERMINATION FOR CAUSE.   This Agreement may be terminated on at least
          thirty (30) days prior written notice by either Party at any time
          during the Term of this Agreement:

          (a)  for material breach by the other Party, which breach remains
               uncured for [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED
               FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***
               in the case of nonpayment of any amount due and [**CONFIDENTIAL
               TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE
               SECURITIES AND EXCHANGE COMMISSION***] for all other breaches,
               each measured from the date written notice of such breach is
               given to the breaching Party, or, if such breach is not
               susceptible of cure within such [**CONFIDENTIAL TREATMENT
               REQUESTED; PORTION OMITTED FILED SEPARATELY WITH THE SECURITIES
               AND EXCHANGE COMMISSION***] period and the breaching Party uses
               diligent good faith efforts to cure such breach, for
               [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED
               SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***] after
               written notice to the breaching Party; or

          (b)  upon the filing or institution of bankruptcy, reorganization,
               liquidation or receivership proceedings, or upon an assignment of
               a substantial portion of the assets for the benefit of creditors
               by the other Party, or in the event a receiver or custodian is
               appointed for such Party's business, or if a substantial portion
               of such Party's business is subject to attachment or similar
               process; PROVIDED, HOWEVER, that in the case of any involuntary
               bankruptcy proceeding such right to terminate shall only become
               effective if the proceeding is not dismissed within
               [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED
               SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION***] after
               the filing thereof.  In the event Wyeth-Ayerst terminates the
               License Agreement under section 9.2.1(b) thereof or this
               Agreement is otherwise terminated under this Section 9.2(b), the
               Parties agree that Wyeth-Ayerst, as a licensee of rights to
               intellectual property under this Agreement, shall retain and may
               fully exercise all of its rights and elections under Title 11,
               including as set forth in Section 9.6 hereof.

     9.3  EFFECT OF TERMINATION OF LICENSE AGREEMENT.

        9.3.1  In the event Wyeth-Ayerst terminates the License Agreement under
               Section 9.2.1(a) thereof, this Agreement, at Wyeth-Ayerst's sole
               option, 


                                          22
<PAGE>

                    may either (i) be terminated by Wyeth-Ayerst or (ii) remain
                    in full force and effect.  If Wyeth-Ayerst elects to
                    terminate this Agreement under Section 9.2(a) hereof, 
                    Wyeth-Ayerst shall have the right, pursuant to the license
                    granted to it in the first sentence of Section 4.4.1 hereof
                    to manufacture the Ingredient for use in Products and
                    GalaGen shall,  promptly after receipt from Wyeth-Ayerst of
                    notice that Wyeth-Ayerst is terminating this Agreement in
                    accordance with Section 9.2(a) hereof (i) in accordance with
                    Section 4.6 hereof, disclose to Wyeth-Ayerst all Know-How
                    and information in GalaGen's possession which is or may be
                    necessary to enable Wyeth-Ayerst, its Affiliates or
                    subcontractors to manufacture the Ingredient and (ii)
                    provide reasonable technical assistance, at GalaGen's
                    expense, that may be necessary for Wyeth-Ayerst, its
                    Affiliates or subcontractors to manufacture the Ingredient.

          9.3.2     In the event that GalaGen terminates the License Agreement
                    under Section 9.2.1(a) thereof, this Agreement shall
                    automatically be terminated.

          9.3.3     If Wyeth-Ayerst terminates the License Agreement in its
                    entirety under Section 9.3 thereof, this Agreement shall
                    automatically be terminated

     9.4  GENERAL CONDITIONS OF EXPIRATION AND TERMINATION.

          9.4.1     The provisions of Articles 5, 8 and 10 and Sections 3.5.2,
                    3.5.3, 4.4.1, 4.6 4.7.2, 4.7.3, 6.4, 6.5, 7.2, 9.6, 11.6 and
                    11.7 shall survive termination or expiration of this
                    Agreement.

          9.4.2     Termination or expiration of this Agreement shall not
                    operate to deprive either Party of any rights or remedies
                    either at law or in equity or to relieve either Party of any
                    of its obligations incurred prior to the effective date of
                    such termination or expiration.

     9.5  NO LIMIT ON REMEDIES.  Nothing herein shall exclude or limit any
          remedies or entitlements whatsoever which the law confers to either
          Party in the event of a breach of contractual obligations by the other
          Party.

     9.6  INSOLVENCY.  
          
          9.6.1     EFFECT ON LICENSES.  All rights and licenses granted under
                    or pursuant to this Agreement by GalaGen to Wyeth-Ayerst
                    are, for all purposes of Section 365(n) of Title 11 of the
                    United States Code ("Title 11"), licenses of rights to
                    "intellectual property" as defined in Title 11.  GalaGen
                    agrees that Wyeth-Ayerst, as licensee of such rights under
                    this Agreement shall retain and may fully exercise all of
                    its rights and elections under Title 11.  GalaGen agrees
                    during the Term of this Agreement to create and maintain
                    current copies or, if not amenable to copying, detailed
                    descriptions or 


                                          23
<PAGE>

                    other appropriate embodiments, to the extent feasible, of
                    all such intellectual property.  If a case is commenced by
                    or against GalaGen under Title 11, GalaGen (in any capacity,
                    including debtor-in-possession) and its successors and
                    assigns (including, without limitation, a Title 11 Trustee)
                    shall,
     
                         (i)  as Wyeth-Ayerst may elect in a written request,
                              immediately upon such request:

                                   (A)  perform all of the obligations provided
                                        in this Agreement to be performed by
                                        GalaGen including, where applicable and
                                        without limitation, providing to
                                        Wyeth-Ayerst portions of such
                                        intellectual property (including
                                        embodiments thereof) held by GalaGen and
                                        such successors and assigns or otherwise
                                        available to them; or 

                                   (B)  provide to Wyeth-Ayerst all such
                                        intellectual property (including all
                                        embodiments thereof) held by GalaGen and
                                        such successors and assigns or otherwise
                                        available to them; and

                         (ii) not interfere with the rights of Wyeth-Ayerst
                              under this Agreement, or any agreement
                              supplemental hereto, to such intellectual property
                              (including such embodiments), including any right
                              to obtain such intellectual property (or such
                              embodiments) from another entity.

          9.6.2     RIGHTS TO INTELLECTUAL PROPERTY.  If a Title 11 case is
                    commenced by or against GalaGen, and this Agreement is
                    rejected as provided in Title 11, and Wyeth-Ayerst elects to
                    retain its rights hereunder as provided in Title 11, then
                    GalaGen (in any capacity, including debtor-in-possession)
                    and its successors and assigns (including, without
                    limitation, a Title 11 Trustee) shall provide to
                    Wyeth-Ayerst all such intellectual property (including all
                    embodiments thereof) held by GalaGen and such successors and
                    assigns, or otherwise available to them, immediately upon
                    Wyeth-Ayerst's written request.  Whenever GalaGen or any of
                    its successors or assigns provides to Wyeth-Ayerst any of
                    the intellectual property licensed hereunder (or any
                    embodiment thereof) pursuant to this Section 9.6,
                    Wyeth-Ayerst shall have the right to perform the obligations
                    of GalaGen hereunder with respect to such intellectual
                    property, but neither such provision nor such performance by
                    Wyeth-Ayerst shall release GalaGen from any such obligation
                    or liability for failing to perform it.


                                          24
<PAGE>

          9.6.3     WYETH-AYERST'S RIGHTS.  All rights, powers and remedies of
                    Wyeth-Ayerst provided herein are in addition to and not in
                    substitution for any and all other rights, powers and
                    remedies now or hereafter existing at law or in equity
                    (including, without limitation, Title 11) in the event of
                    the commencement of a Title 11 case by or against GalaGen. 
                    Wyeth-Ayerst, in addition to the rights, power and remedies
                    expressly provided herein, shall be entitled to exercise all
                    other such rights and powers and resort to all other such
                    remedies as may now or hereafter exist at law or in equity
                    (including, without limitation, Title 11) in such event. 
                    The Parties agree that they intend the foregoing
                    Wyeth-Ayerst rights to extend to the maximum extent
                    permitted by law, including, without limitation, for
                    purposes of Title 11:

                         (i)  the right of access to any intellectual property
                              (including all embodiments thereof) of GalaGen, or
                              any Third Party with whom GalaGen contracts to
                              perform an obligation of GalaGen under this
                              Agreement, and, in the case of the Third Party,
                              which is necessary for the development,
                              registration, Manufacture and marketing of the
                              Ingredient and/or Products; and 

                         (ii) the right to contract directly with any Third
                              Party described in (i) to complete the contracted
                              work.

10.  CONFIDENTIALITY.

     10.1 NONDISCLOSURE OBLIGATION.  Each of GalaGen and Wyeth-Ayerst shall use
          only in accordance with this Agreement and shall not disclose to any
          Third Party any information received by it from the other Party in
          connection with this Agreement (the "Information"), without the prior
          written consent of the other Party.  The foregoing obligations shall
          survive the expiration or earlier termination of this Agreement
          [**CONFIDENTIAL TREATMENT REQUESTED; PORTION OMITTED FILED SEPARATELY
          WITH THE SECURITIES AND EXCHANGE COMMISSION***].  These obligations
          shall not apply to Information that: 
               
               (i)  is known by the receiving Party at the time of its receipt,
                    and not through a prior disclosure by the disclosing Party,
                    as documented by business records;

              (ii)  is at the time of disclosure or thereafter becomes published
                    or otherwise part of the public domain without breach of
                    this Agreement by the receiving Party;


                                          25
<PAGE>

              (iii) is subsequently disclosed to the receiving Party by a Third
                    Party who has the right to make such disclosure;

               (iv) is developed by the receiving Party independently of the
                    Information or other information received from the
                    disclosing Party and such independent development can be
                    documented by the receiving Party;
               
               (v)  is disclosed to any institutional review board of any entity
                    conducting clinical trials or any governmental or other
                    regulatory agencies in order to obtain patents or to gain
                    approval to conduct clinical trials or to market the
                    Ingredient and/or Products, but such disclosure may be made
                    only to the extent reasonably necessary to obtain such
                    patents or authorizations; and, in which case reasonable
                    effort shall be taken to maintain the confidentiality of
                    such Information, or
               
               (vi) is required by law, regulation, rule, act or order of any
                    governmental authority or agency to be disclosed by a Party,
                    PROVIDED that notice is promptly delivered to the other
                    Party in order to provide an opportunity to seek a
                    protective order or other similar order with respect to such
                    Information and thereafter the disclosing Party discloses to
                    the requesting entity only the minimum Information required
                    to be disclosed in order to comply with the request, whether
                    or not a protective order or other similar order is obtained
                    by the other Party.

     10.2 PERMITTED DISCLOSURES.  Information may be disclosed to employees,
          agents, consultants, sublicensees or suppliers of the recipient Party
          or its Affiliates, but only to the extent required to accomplish the
          purposes of this Agreement and only if the recipient Party obtains
          prior agreement from its employees, agents, consultants, sublicensees
          or suppliers to whom disclosure is to be made to hold in confidence
          and not make use of such Information for any purpose other than those
          permitted by this Agreement.  Each Party will use at least the same
          standard of care as it uses to protect proprietary or confidential
          information of its own to ensure that such employees, agents,
          consultants, sublicensees or suppliers do not disclose or make any
          unauthorized use of the Information.
          
     10.3 DISCLOSURE OF AGREEMENT.  Neither GalaGen nor Wyeth-Ayerst shall
          release to any Third Party or publish in any way any non-public
          information with respect to the terms of this Agreement or concerning
          their cooperation without the prior written consent of the other,
          which consent will not be unreasonably withheld or delayed, PROVIDED,
          HOWEVER, that either Party may disclose the terms of this Agreement to
          the extent required to comply with applicable laws, including without
          limitation the rules and regulations promulgated by the United States


                                          26
<PAGE>

          Securities and Exchange Commission and the Party intending to disclose
          the terms of this Agreement shall provide the nondisclosing Party an
          opportunity to review and comment on the intended disclosure which is
          reasonable under the circumstances.  Notwithstanding any other
          provision of this Agreement, each Party may disclose the terms of this
          Agreement to lenders, investment bankers and other financial
          institutions of its choice solely for purposes of financing the
          business operations of such Party either (i) upon the written consent
          of the other Party or (ii) if the disclosing Party uses reasonable
          efforts to obtain a signed confidentiality agreement with such
          financial institution with respect to such information on terms
          substantially similar to those contained in this Article 10.

     10.4 PUBLICITY.  Subject to Section 10.3, all publicity, press releases and
          other announcements relating to this Agreement or the transactions
          contemplated hereby shall be reviewed in advance by, and shall be
          subject to the approval of, both Parties.
          

11.  MISCELLANEOUS

     11.1 FORCE MAJEURE.  Neither Party shall be liable to the other for delay
          or failure in the performance of the obligations on its part contained
          in this Agreement if and to the extent that such failure or delay is
          due to circumstances beyond its control which it could not have
          avoided by the exercise of reasonable diligence.  It shall notify the
          other Party promptly should such circumstances arise, giving an
          indication of the likely extent and duration thereof, and shall use
          all commercially reasonable efforts to resume performance of its
          obligations as soon as practicable.

     11.2 ASSIGNMENT.  
          
          11.2.1    ASSIGNMENT BY GALAGEN.  GalaGen may assign any of its rights
                    or obligations under this Agreement in any country to any of
                    its Affiliates, for so long as they remain Affiliates. 
                    GalaGen may also assign its rights and obligations under
                    this Agreement in connection with a merger or similar
                    reorganization or the sale of all or substantially all of
                    its assets.  GalaGen shall not otherwise assign any of its
                    rights or obligations under this Agreement without the prior
                    written consent of Wyeth-Ayerst, which consent may be
                    provided or withheld in Wyeth-Ayerst's sole discretion.  Any
                    assignment under this Section 11.2.1 by GalaGen of its
                    rights and/or obligations under this Agreement shall not
                    relieve GalaGen of its responsibilities for the performance
                    of its obligations under this Agreement.
               
          11.2.2    ASSIGNMENT BY WYETH-AYERST.  Wyeth-Ayerst may assign any of
                    its rights or obligations under this Agreement in any
                    country to any of its Affiliates or to one or more Third
                    Parties.  Wyeth-Ayerst shall notify 


                                          27
<PAGE>

                    GalaGen, in writing, upon making any such assignment.  In
                    the event Wyeth-Ayerst assigns any of its rights or
                    obligations under this Agreement in connection with a merger
                    or similar reorganization or the sale of all or
                    substantially all of its assets or a sale of that part of
                    its business relating to the subject matter of this
                    Agreement, no intellectual property rights of the acquiring
                    corporation shall be included in the technology licensed
                    hereunder.  Any assignment under this Section 11.2.2 by
                    Wyeth-Ayerst shall not relieve Wyeth-Ayerst of its
                    responsibilities for the performance of its obligations
                    under this.
               
          11.2.3    BINDING NATURE OF ASSIGNMENT.  This Agreement shall be
                    binding upon and inure to the benefit of the successors and
                    permitted assigns of the Parties.  Any assignment not in
                    accordance with this Section 11.2 shall be void.
          
     11.3 NO WAIVER.  The failure of either Party to require performance by the
          other Party of any of that other Party's obligations hereunder shall
          in no manner affect the right of such Party to enforce the same at a
          later time.  No waiver by any Party hereto of any condition, or of the
          breach of any provision, term, representation or warranty contained in
          this Agreement, whether by conduct or otherwise, in any one or more
          instances, shall be deemed to be or construed as a further or
          continuing waiver of any such condition or breach, or of any other
          condition or of the breach of any other provision, term,
          representation or warranty hereof.
          
     11.4 SEVERABILITY.  If a court or other tribunal of competent jurisdiction
          should hold any term or provision of this Agreement to be excessive,
          or invalid, void or unenforceable, the offending term or provision
          shall be deleted, and, if possible, replaced by a term or provision
          which, so far as practicable achieves the legitimate aims of the
          Parties.
          
     11.5 RELATIONSHIP BETWEEN THE PARTIES.   Both Parties are independent
          contractors under this Agreement.  Nothing herein contained shall be
          deemed to create an employment, agency, joint venture or partnership
          relationship between the Parties hereto or any of their agents or
          employees, or any other legal arrangement that would impose liability
          upon one Party for the act or failure to act of the other Party. 
          Neither Party shall have any express or implied power to enter into
          any contracts or commitments or to incur any liabilities in the name
          of, or on behalf of, the other Party, or to bind the other Party in
          any respect whatsoever.
          
     11.6 CORRESPONDENCE AND NOTICES.
          
          11.6.1    Correspondence, reports, documentation , and any other
                    communication in writing between the Parties in the course
                    of implementation of this Agreement shall be in writing and
                    sent by prepaid air mail, or by facsimile confirmed by
                    prepaid registered or certified air mail letter, and shall
                    be 


                                          28
<PAGE>

                    deemed to have been properly served to the addressee upon
                    receipt of such written communication.
               
          11.6.2    In the case of GalaGen, the proper address for
                    communications and for all payments shall be:

                              GalaGen, Inc.
                              4001 Lexington Avenue North
                              Arden Hills, Minnesota  55126  USA
                              Attn:  Chief Executive Officer
                    
                    and it the case of Wyeth-Ayerst, the proper address for
                    communications and for all payments shall be:
               
                              Wyeth-Ayerst Laboratories
                              555 Lancaster Avenue
                              St. Davids, Pennsylvania  19087
                              Attn:  Senior Vice President, Global Business
                              Development
                    
                    With a copy to:
               
                              American Home Products Corporation
                              5 Giralda Farms
                              Madison, New Jersey  07940
                              Attn:  Senior Vice President and General Counsel
          
     11.7 CHOICE OF LAW.  This Agreement is subject to and governed by the laws
          of the State of Delaware, excluding its conflict of laws provisions.
          
     11.8 ENTIRE AGREEMENT; AMENDMENT. This Agreement, together with the other
          Transaction Agreements, including the Exhibits and Schedules hereto
          and thereto and all the covenants, promises, agreements, warranties,
          representations, conditions and understandings contained herein and
          therein sets forth the complete, final and exclusive agreement between
          the Parties and supersedes and terminates all prior and
          contemporaneous agreements and understandings between the Parties,
          whether oral or in writing.  There are no covenants, promises,
          agreements, warranties, representations, conditions or understandings,
          either oral or written, between the Parties other than as are set
          forth in the Transaction Agreements.  No subsequent alteration,
          amendment, change, waiver or addition to this Agreement shall be
          binding upon the Parties unless reduced to writing and signed by an
          authorized officer of each Party.  No understanding, agreement,
          representation or promise, not explicitly set forth herein, has been
          relied on by either Party in deciding to execute this Agreement. 


                                          29
<PAGE>

    11.9  HEADINGS. The headings and captions used in this Agreement are solely
          for the convenience of reference and shall not affect its
          interpretation.
          
    11.10 COUNTERPARTS.  This Agreement may be executed in one or more
          counterparts each of which shall be an original and all of
          which shall constitute together the same document.

    11.11 FURTHER ACTIONS.  Each Party agrees to execute, acknowledge
          and deliver such further instruments, and to do all other
          acts, as may be necessary or appropriate in order to carry
          out the purposes and intent of this Agreement including,
          without limitation, any filings with any antitrust agency
          which may be required.

     IN WITNESS WHEREOF, this Agreement has been executed by the duly authorized
representatives of the Parties as of the date set forth above.


AMERICAN HOME PRODUCTS CORPORATION      GALAGEN INC.


/s/ Tuan Ha-Ngoc                        /s/ Robert A. Hoerr
-----------------------------------     -----------------------------------
Name:  Tuan Ha-Ngoc                     Name:  Robert A. Hoerr
Title: Vice President - Strategic       Title: President & CEO
       Development


                                          30