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                                                                  Exhibit 10.703
                                                                  EXECUTION COPY

                         SUBSCRIPTION AGREEMENT dated as of November 20, 1994
                    (this "Agreement"), among CIBA-GEIGY LIMITED, a Swiss
                    corporation ("Ciba"), CIBA-BIOTECH PARTNERSHIP, INC., a
                    Delaware corporation ("Purchaser") and an indirectly wholly
                    owned subsidiary of Ciba, CIBA-GEIGY CORPORATION, a New York
                    corporation ("C Corp"), and CHIRON CORPORATION, a Delaware
                    corporation (the "Company").

               WHEREAS Ciba, C Corp, Purchaser and the Company have entered into
     the Investment Agreement dated as of the date hereof (the "Investment
     Agreement");

               WHEREAS each of Ciba, C Corp, Purchaser and the Company have each
     determined to engage in the transactions contemplated by the Investment
     Agreement pursuant to which transactions Ciba initially will own a minority
     of the then outstanding shares of Common Stock of the Company;

               WHEREAS in partial consideration for the Company to enter into
     the Investment Agreement and certain related agreements and arrangements,
     Purchaser is willing to subscribe to purchase additional Common Shares; and

               WHEREAS Purchaser and the Company desire to set forth in this
     Agreement their agreement with respect to the purchase by the Purchaser of
     shares ("Common Shares") of the Company's Common Stock, $0.01 par value
     (the "Common Stock"), as more completely described in this Agreement.

               NOW, THEREFORE, in consideration of the mutual promises and
     agreements contained herein and for other good and valuable consideration,
     the sufficiency and receipt of which are hereby acknowledged, the parties
     hereto hereby agree as follows:

               SECTION 1. DEFINITIONS; INTERPRETATION. The rules of
     interpretation set forth in Section 7.04 of the Investment Agreement shall
     apply to this Agreement, and the provisions thereof shall be deemed to be
     incorporated by reference herein. As used in this Agreement, the following
     terms shall have the following meanings:

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                                                                               2


               "AFFILIATE" has the meaning assigned to such term in the
     Governance Agreement.

               "ANCILLARY AGREEMENTS" has the meaning assigned to such term in
     the Investment Agreement.

               "CLOSING" has the meaning assigned to such term in the Investment
     Agreement.

               "CLOSING DATE" has the meaning assigned to such term in the
     Investment Agreement.

               "EXCHANGE ACT" has the meaning assigned to such term in the
     Governance Agreement.

               "FAIR MARKET VALUE" means, as of any date of determination, the
     average of the closing sale prices of Common Shares during the 10 trading
     day period immediately preceding such date of determination on the
     principal United States securities exchange registered under the Exchange
     Act on which Common Shares are listed or, if Common Shares are not listed
     on any such exchange, the average of the closing sale prices or the closing
     bid quotations of Common Shares during the 10 trading day period preceding
     such date of determination on the Nasdaq National Market or any comparable
     system then in use or, if no such quotations are available, the fair market
     value of Common Shares as of such date of determination as determined in
     good faith by a majority of the Independent Directors.

               "GOVERNANCE AGREEMENT" has the meaning assigned to such term in
     the Investment Agreement.

               "HSR ACT" has the meaning assigned to such term in the Investment
     Agreement.

               "INVESTMENT AGREEMENT" has the meaning assigned to such term
     above.

               "MARKET PRICE OPTION AGREEMENT" means the Market Price Option
     Agreement dated as of the date hereof among Ciba, C Corp, Purchaser and
     the Company.

               "PERSON" shall have the meaning assigned to such term in the
     Governance Agreement.

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               "REGISTRATION RIGHTS AGREEMENT" means the Registration Rights
     Agreement dated as of the date hereof among Ciba, C Corp, Purchaser and the
     Company.

               "REQUEST NOTICE" has the meaning assigned to such term in
     Section 2(b).

               "SEC" has the meaning assigned to such term in the Governance
     Agreement.

               "SEC DOCUMENTS" shall mean the most recently filed annual report
     on Form 10-K of the Company filed with the SEC and each report, schedule,
     form, statement and other documents filed by the Company with the SEC
     thereafter.

               "SECURITIES ACT" has the meaning assigned to such term in the
     Governance Agreement.

               "SUBSCRIPTION AMOUNT" means, initially, $500,000,000, and,
     thereafter, such amount as reduced by the aggregate price paid from time to
     time after the Closing by the Purchaser or any of its Affiliates to the
     Company or any Subsidiary of the Company for each purchase from the Company
     or any Subsidiary of the Company of any Equity Securities by any of them,
     whether pursuant to the Market Price Option Agreement, the Governance
     Agreement, this Agreement or otherwise except for (i) purchases by the
     Purchaser or its Affiliates in connection with collaborations entered into
     by Purchaser or its Affiliates and the Company in accordance with the terms
     of the Cooperation and Collaboration Agreement dated as of the date hereof
     between Ciba and the Company (ii) Equity Securities issued to Ciba or its
     Affiliates in accordance with the terms of the Research and Development
     Agreement referred to in Section 5.16 of the Investment Agreement.

               "SUBSCRIPTION CLOSING" has the meaning assigned to such term in
     Section 2(b).

               "SUBSCRIPTION CLOSING DATE" has the meaning assigned to such term
     in Section 2(b).

               "SUBSCRIPTION PERIOD" means the eleven year period commencing
     with the Closing Date.

               SECTION 2. SALE AND PURCHASE OF SHARES.

     (a) Subject to the terms and conditions herein set forth

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     and Section 2.04 of the Governance Agreement, the Purchaser agrees to
     purchase from the Company, and the Company agrees to sell to Purchaser,
     from time to time and at any time during the Subscription Period upon each
     request of the Company, Common Shares for an aggregate purchase price at
     any Subscription Closing not in excess of the Subscription Amount remaining
     as of the applicable Subscription Closing Date.

               (b)  In order for the Company to request Purchaser to purchase
     any of the Shares pursuant to Section 2(a), the Company shall, prior to the
     expiration of the Subscription Period, give written notice to Purchaser of
     such request (a "Request Notice"), specifying the number of shares to be
     purchased (which shall be a number that results in an aggregate purchase of
     at least the lesser of $5,000,000 and the then remaining Subscription
     Amount) and the place, time and date of the closing of such purchase (each
     a "Subscription Closing" or a "Subscription Closing Date"), which date
     shall not be less than five business days nor more than ten business days
     from the date on which such notice is delivered.

               (c)  At each Subscription Closing, the Company shall deliver to
     Purchaser all of the Common Shares to be purchased by delivery of a
     certificate or certificates evidencing such Common Shares in the
     denominations designated by Purchaser by notice to the Company given by the
     Purchaser prior to the Subscription Closing. Each of such Common Shares
     shall bear the legend set forth in Section 3.02(d) of the Investment
     Agreement. If at the time of issuance of any Common Shares pursuant hereto,
     the Company shall not have redeemed the Rights (as defined in the Rights
     Agreement dated as of August 29, 1994, between the Company and Continental
     Stock Transfer and Trust Company, as Rights Agent, as the same may be
     amended from time to time), then each Common Share issued pursuant hereto
     shall have attached to it Rights or new rights with terms substantially the
     same as, and at least as favorable to Purchaser as, are provided generally
     to holders of shares of Common Stock under the Rights.

               (d)  Notwithstanding anything in the foregoing to the contrary,
     the Company shall have no rights, and Ciba shall have no obligations, under
     this Section 2 or Section 3 hereof if during the 10 trading day period (or
     the date of determination if no quotes of the type referred to in the
     definition of Fair Market Value are available) applicable to

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     the determination of the Fair Market Value with respect to any proposed
     purchase and sale of Common Shares pursuant to this Agreement the Company
     is in possession of any material adverse undisclosed information regarding
     the Company that would be required to be disclosed by the Company in a
     registration statement under the Securities Act in connection with a public
     offering of Common Stock of the Company.

               SECTION 3. PAYMENT; FUNDING. (a) In the event the Company
     requests, pursuant to Section 2, Purchaser to purchase any Common Shares,
     Purchaser shall, at the related Subscription Closing, deliver by wire
     transfer to an account designated at least two business days in advance of
     such Subscription Closing an amount equal to the Fair Market Value of the
     Common Shares being issued and sold by the Company to the Purchaser
     determined as of the business day that occurs three business days prior to
     such Subscription Closing.

               (b)  Ciba and/or C Corp shall provide Purchaser on a timely basis
     all funds required for Purchaser to fulfill its obligation under this
     Agreement to purchase Common Shares.

               SECTION 4. REGISTRATION RIGHTS. The Common Shares purchased
     pursuant to this Agreement shall be entitled to the registration rights
     provided for in the Registration Rights Agreement.

               SECTION 5. REPRESENTATIONS AND WARRANTIES. (a) The Company hereby
     represents and warrants to Purchaser as follows:

               (i)   The execution and delivery of this Agreement and the
          consummation of the transactions contemplated hereby have been duly
          and validly authorized by the Board of Directors of the Company and no
          other corporate proceedings on the part of the Company are necessary
          to authorize this Agreement or to consummate the transactions
          contemplated hereby. This Agreement has been duly and validly executed
          and delivered by the Company. Prior to delivery of any Request Notice
          pursuant to Section 2(b), the Company will have taken all necessary
          corporate and other action to authorize, and to permit it to deliver
          the full number of Common Shares purchasable pursuant to such Request
          Notice.

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          Upon issuance, all of such Common Shares shall be duly authorized,
          validly issued, fully paid and nonassessable and will be approved for
          quotation on the Nasdaq National Market, or for quotation or listing
          on the principal trading market for the Common Shares at the time of
          issuance. Upon delivery of such Common Shares they shall be free and
          clear of all claims, liens, encumbrances, security interests and
          charges of any nature whatsoever and shall not be subject to any
          preemptive right of any shareholder of the Company;

               (ii)   Except for filings under the HSR Act, if applicable, no
          filing with, and no permit, authorization, consent or approval of, any
          state, Federal or foreign public body or authority is necessary for
          the execution of this Agreement by the Company and the consummation by
          the Company of the transactions contemplated hereby (including the
          sale of Common Shares hereunder);

               (iii)  The Company has filed all required reports, schedules,
          forms, statements and other documents with the SEC during the current
          calendar year and the two prior calendar years. As of their respective
          dates, the SEC Documents complied in all material respects with the
          requirements of the Securities Act or the Exchange Act, as the case
          may be, and the rules and regulations of the SEC promulgated
          thereunder applicable to such SEC Documents, and none of the SEC
          Documents contained any untrue statement of a material fact or omitted
          to state a material fact required to be stated therein or necessary in
          order to make the statements therein, in light of the circumstances
          under which they were made, not misleading. The financial statements
          of the Company included in the SEC Documents comply as to form in all
          material respects with applicable accounting requirements and the
          published rules and regulations of the SEC with respect thereto, have
          been prepared in accordance with generally accepted accounting
          principles (except, in the case of unaudited statements, as permitted
          by Form 10-Q of the SEC) applied on a consistent basis during the
          periods involved (except as may be indicated in the notes thereto) and
          fairly present the consolidated financial position of the Company and
          its consolidated subsidiaries as of the dates thereof and their
          consolidated statements of operations, stockholders equity and cash
          flows for the periods then ended



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          (subject, in the case of unaudited statements, to normal year-end
          audit adjustments);

              (iv) Except for filings under the HSR Act, if applicable, neither
          the execution and delivery of this Agreement by the Company nor the
          consummation by the Company of the transactions contemplated hereby
          nor compliance by the Company with any of the provisions hereof shall
          (x) conflict with or result in any breach of, or require any vote
          under, any provision of the Certificate of Incorporation of the
          Company or the By-laws of the Company, (y) result in a violation or
          breach of, or constitute (with or without notice or lapse of time or
          both) a default (or give rise to any third party right of termination,
          cancelation, material modification or acceleration) under any of the
          terms, conditions or provisions of any note, bond, mortgage,
          indenture, license, contract, agreement or other instrument or
          obligation to which the Company or any of its Subsidiaries is a party
          or by which any of them or any of their properties or assets may be
          bound or (z) violate any order, writ, injunction, decree, statute,
          rule or regulation applicable to the Company or its Subsidiaries or
          any of their properties or assets, except in the case of (y) or (z)
          for violations, breaches or defaults which would not, in the
          aggregate, have a material adverse effect on the business, assets,
          results of operations or financial condition of the Company and its
          subsidiaries taken as a whole or materially impair the ability of the
          Company to perform its obligations hereunder; and

               (v) This Agreement has been approved by a two-thirds vote of the
          "Continuing Directors" (as defined in Article ELEVENTH of the
          Company's Certificate of Incorporation).

               (b)  Each of the Purchaser, Ciba and C Corp hereby represents and
     warrants as to itself as follows:

               (i) The execution and delivery of this Agreement and the
          consummation of the transactions contemplated hereby (including the
          exercise of the Option) by the Closing Date will have been duly and
          validly authorized by its Board of Directors and no other corporate
          proceedings on its part are necessary to authorize this Agreement or
          to consummate the transactions

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          contemplated hereby. This Agreement has been duly and validly executed
          and delivered by it.

               (ii)   Except for filings under the HSR Act, if applicable,
          neither the execution and delivery of this Agreement by it nor the
          consummation by it of the transactions contemplated hereby nor
          compliance by it with any of the provisions hereof shall (x) conflict
          with or result in any breach of, or require any vote under, any
          provision of its Certificate of Incorporation or its By-laws, (y)
          result in a violation or breach of, or constitute (with or without
          notice or lapse of time or both) a default (or give rise to any third
          party right of termination, cancelation, material modification or
          acceleration) under any of the terms, conditions or provisions of any
          note, bond, mortgage, indenture, license, contract, agreement or other
          instrument or obligation to which it or any of its Subsidiaries is a
          party or by which any of them or any of their properties or assets may
          be bound or (z) violate any order, writ, injunction, decree, statute,
          rule or regulation applicable to it or its Subsidiaries or any of
          their properties or assets, except in the case of (y) or (z) for
          violations, breaches or defaults which would not, in the aggregate,
          have a material adverse effect on the business, assets, results of
          operations or financial condition of it and its Subsidiaries taken as
          a whole or materially impair its ability to perform its obligations
          hereunder.

               (c)  Purchaser hereby represents and warrants to the Company that
     any Common Shares acquired by Purchaser hereunder will be acquired for
     investment only and not with a view to any public distribution of all or
     any portion thereof, and Purchaser will not offer to sell or otherwise
     dispose of all or any portion of such Common Shares in violation of any of
     the registration requirements of the Securities Act.

               SECTION 6. CONDITIONS PRECEDENT. The Purchaser's obligation to
     purchase any Common Shares is subject to the satisfaction as of the
     applicable Subscription Closing Date of the following conditions:

               (a) The representations and warranties of the Company made in
          this Agreement shall be true and correct in all material respects as
          of the date of this

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     Agreement and as of the applicable Subscription Closing Date with the same
     effect as if made at and as of such Subscription Closing Date, except to
     the extent such representations and warranties expressly relate to an
     earlier time. The Company shall have performed in all material respects the
     covenants and agreements of the Company contained in the this Agreement,
     the Investment Agreement, the Governance Agreement and each of the other
     Ancillary Agreements required to be performed at or prior to the applicable
     Subscription Closing and no material breach, or event which would, with the
     giving of notice or the passage of time or both, constitute a default,
     shall have occurred and be continuing thereunder. Purchaser shall have
     received a certificate from a senior officer of the Company dated such
     Subscription Closing Date, as to the satisfaction of this Section 6(a).

               (b)  The Company, Ciba and its Affiliates shall have obtained or
     made all consents, approvals, orders, licenses, permits and authorizations
     of, and registrations, declarations and filings with, any governmental
     authority or any other Person required to be obtained or made by or with
     respect to the Company, Ciba or Ciba's Affiliates in connection with such
     sale.

               (c)  There shall not be threatened or pending by any governmental
     authority any suit, action or proceeding, and there shall not be pending by
     any other Person, any suit, action or proceeding, which has a reasonable
     likelihood of success, seeking to restrain or prohibit the issuance and
     sale of the applicable Common Shares, and no injunction, decree or order of
     any governmental authority shall be in effect as of the applicable
     Subscription Closing which would restrain or prohibit the issuance and sale
     of the applicable Common Shares.

               (d)  The issuance and sale of the applicable Common Shares shall
     not violate, or cause the violation of, any applicable law or regulations.

               (e)  Ciba shall not become subject to any materially greater
     regulatory requirements or subject its existing investment in the Company
     to any additional material restriction due to the increase in its
     percentage ownership of the Company resulting from such purchase of Common
     Shares, in each case due to

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          (1) any change of law regulations after the date hereof or any changed
          circumstance arising therefrom or (2) any change in circumstances
          due to any action by the Company or any of its Subsidiaries.

               (f)  The Purchaser shall have received an opinion dated the
          applicable Subscription Agreement Closing Date of the General Counsel
          of the Company to the effect that the Common Shares being purchased by
          the Company on such date are duly authorized, validly issued, fully
          paid and nonassessable.

               The failure to satisfy any of the foregoing conditions as of any
     Subscription Closing Date and the resulting cancellation of the purchase
     and sale of the Common Shares proposed to be sold to the Company on such
     date shall not prohibit the Company from giving further Request Notices. In
     the event that there shall be in effect as of any Subscription Closing any
     injunction, decree or order referred to in Section 6(c), the Company or
     Purchaser, as applicable, shall use all reasonable efforts to have such
     injunction, decree or order vacated, lifted or overturned.

               SECTION 7. MISCELLANEOUS. (a) From time to time, at any of the
     other parties' request and without further consideration, each party hereto
     shall execute and deliver such additional documents, transfers,
     assignments, endorsements, consents and other instruments and take all such
     further action as may be necessary or desirable to consummate the
     transactions contemplated by this Agreement, including, without limitation,
     to vest in Purchaser good title to any Common Shares purchased hereunder.

               (b)  All notices, requests, claims, demands and other
     communications hereunder shall be in writing and shall be given (and shall
     be deemed to have been duly given upon receipt) by delivery in person, by
     cable, facsimile transmission, telegram or telex or by registered or
     certified mail (postage prepaid, return receipt requested) to the
     respective parties and at the addresses (or at such other address for a
     party as shall be specified in a notice given in accordance with this
     paragraph) specified in Section 7.02 of the Investment Agreement.

               (d)  No provision of this Agreement may be amended or waived
     unless such amendment or waiver is in writing and signed, in the case of an
     amendment, by the parties hereto,

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     or in the case of a waiver, by the party against whom the waiver is to be
     effective.

               (e) No failure or delay by any party in exercising any right,
     power or privilege hereunder shall operate as waiver thereof nor shall
     any single or partial exercise thereof preclude any other or further
     exercise thereof or the exercise of any other right, power or privilege.
     The rights and remedies herein provided shall be cumulative and not
     exclusive of any rights or remedies provided by law.

               (f)  If any term or provision of this Agreement or the
     application thereof to either party or set of circumstances shall, in any
     jurisdiction and to any extent, be finally held invalid or unenforceable,
     such term or provision shall only be ineffective as to such jurisdiction,
     and only to the extent of such invalidity or unenforceability, without
     invalidating or rendering unenforceable any other terms or provisions of
     this Agreement or under any other circumstances, and the parties shall
     negotiate in good faith a substitute provision which comes as close as
     possible to the invalidated or unenforceable term or provision, and which
     puts each party in a position as nearly comparable as possible to the
     position it would have been in but for the finding of invalidity or
     unenforceability, while remaining valid and enforceable.

               (g) The Investment Agreement, the Governance Agreement, the
     Registration Rights Agreement, this Agreement and the other Ancillary
     Agreements and the agreements contemplated hereby and thereby, constitute
     the entire agreement among the parties hereto with respect to the subject
     matter hereof and thereof and supersede all prior agreements and
     undertakings, both written and oral, between the parties with respect to
     the subject matter hereof.

               (h) Neither party to this Agreement shall assign any of its
     rights or obligations hereunder without the prior written consent of the
     other party hereto, except that Purchaser, Parent and C Corp may assign all
     or any of its rights and obligations hereunder to Ciba or to any of Ciba's
     wholly owned Subsidiaries but no such assignment shall relieve such parties
     of their obligations hereunder.

               (i) This Agreement shall be binding upon and inure solely to the
     benefit of each party hereto, and

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     nothing in this Agreement, express or implied, is intended to or shall
     confer upon any other person, other than the parties hereto and their
     respective permitted successors and assigns, any right, benefit or remedy
     of any nature or kind whatsoever under or by reason of this Agreement.

               (j)  This Agreement shall be governed by, and construed in
     accordance with, the laws of the State of Delaware applicable to contracts
     executed and to be fully performed in that State. All actions and
     proceedings arising out of or relating to this Agreement shall be brought
     by the parties and heard and determined only in a Delaware state court or a
     federal court sitting in that State and the parties hereto consent to
     jurisdiction before and waive any objectives of venue to the Delaware
     Chancery Court.

               (k)  This Agreement may be executed in one or more counterparts,
     each of which shall be deemed an original but all of which taken together
     shall constitute one and the same agreement.

               (l)  The parties hereto each hereby irrevocably waives all right
     to trial by jury in any action, proceeding or counterclaim (whether based
     on contract, tort or otherwise) arising out of or relating to this
     Agreement or the actions of any party hereto in the negotiation,
     administration, performance and enforcement thereof.

               IN WITNESS WHEREOF, the Company, Purchaser, Ciba and C Corp have
     caused this Agreement to be duly executed as of the day and year first
     above written.


                                     CIBA BIOTECH PARTNERSHIP, INC.,

                                        by   /s/ McGraw
                                             --------------------------
                                             Name:
                                             Title:

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                                                                              13


                                     CHIRON CORPORATION,

                                        by   /s/ William J. Rutter
                                             --------------------------
                                             Name:
                                             Title:


                                     CIBA-GEIGY LIMITED,

                                        by   /s/ Alex Krauer
                                             --------------------------
                                             Name:
                                             Title:

                                        by   /s/ John Cheesmond
                                             --------------------------
                                             Name:
                                             Title:


                                     CIBA-GEIGY CORPORATION,

                                        by   /s/ McGraw
                                             --------------------------
                                             Name:
                                             Title: