SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D

                    Under the Securities Exchange Act of 1934
                               (Amendment No. 4 )*
                                             ---

                                 SOMATOGEN, INC.
                                ----------------
                                (Name of Issuer)

                          COMMON STOCK, $.001 PAR VALUE
                         -------------------------------
                         (Title of Class of Securities)

                                    83444910
                                 --------------
                                 (CUSIP Number)

           DANIEL P. CARMICHAEL, SECRETARY AND DEPUTY GENERAL COUNSEL,
                 ELI LILLY AND COMPANY, LILLY CORPORATE CENTER,
                    INDIANAPOLIS, INDIANA 46285 317-276-2526
               -------------------------------------------------
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                                FEBRUARY 23, 1998
                            -------------------------
                      (Date of Event which Requires Filing
                               of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(b)(3) or (4), check the following box [ ].

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).

(Continued on following pages)


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CUSIP No.                                                 83444910

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(1)     Names of Reporting Persons:                       Eli Lilly and Company
        S.S. or I.R.S. Identification                     35-0470950
        Nos. of Above Persons

- --------------------------------------------------------------------------------

(2)     Check the Appropriate Box                         (a) _________________
        if a Member of a Group                            (b) _________________
                                                          Not Applicable

- --------------------------------------------------------------------------------

(3)     SEC Use Only

- -------------------------------------------------------------------------------
(4)     Source of Funds                                   Not Applicable

- --------------------------------------------------------------------------------
(5)     Check if Disclosure of Legal
        Proceedings is Required Pursuant
        to Items 2(d) or 2(e)                             Not Applicable

- --------------------------------------------------------------------------------
(6)     Citizenship or Place of Organization              Indiana

- --------------------------------------------------------------------------------
Number of Shares             (7)   Sole Voting            None
  Beneficially Owned               Power
  by Each Reporting          (8)   Shared Voting          2,954,104
  Person With                      Power
                             (9)   Sole Dispositive       2,954,104
                                   Power
                             (10) Shared Disposi-         None
                                   tive Power

- --------------------------------------------------------------------------------

(11)   Aggregate Amount Beneficially                      2,954,104
       Owned by Each Reporting Person
- --------------------------------------------------------------------------------

(12)   Check if the Aggregate Amount                      Not Applicable
       In Row (11) Excludes Certain Shares

- --------------------------------------------------------------------------------

(13)   Percent of Class Represented                       14.1%
       by Amount in Row (11)

- --------------------------------------------------------------------------------

(14)   Type of Reporting Person    CO

- --------------------------------------------------------------------------------


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Item 6.    Contracts, Arrangements, Understandings or Relationships With
           Respect to Securities of the Issuer.

        On February 23, 1998, Eli Lilly and Company ("Lilly") entered into a
Voting Agreement with Baxter International Inc. ("Baxter") in connection with a
proposed acquisition of the Issuer by Baxter. The Voting Agreement obligates
Lilly to vote its shares of the Issuer's common stock in favor of the proposed
merger with Baxter and against any action that would compete with or otherwise
adversely affect the proposed merger. Lilly has agreed, upon request, to deliver
a proxy to Baxter (irrevocable to the extent permissible under Delaware law) to
effectuate the foregoing. In addition, Lilly has agreed not to (i) directly or
indirectly participate in a proxy solicitation in opposition to or competition
with the proposed merger; (ii) directly or indirectly encourage, initiate or
cooperate in a stockholders' vote or consent in opposition to or competition
with the proposed merger; or (iii) dispose of its shares of the Issuer's common
stock prior to the termination of the Voting Agreement. See Sections 2-5 of the
Voting Agreement (filed herewith as Exhibit A) which are incorporated by
reference in this Item 6.

        The Voting Agreement terminates upon the earliest of (i) the
consummation of the proposed merger with Baxter; (ii) the termination of the
merger agreement with Baxter, or (iii) a determination by the Board of Directors
of Issuer that it has received a Superior Competing Bid as defined in Section 8
of the Voting Agreement; or (iv) September 30, 1998. See Section 8 of the Voting
Agreement which is incorporated by reference in this Item 6.

Item 7.      Material to be Filed as Exhibits.

             Exhibit A.  Voting Agreement dated as of February 23, 1998,
                         between Lilly and Baxter International Inc.

                                    SIGNATURE

        After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

                                            ELI LILLY AND COMPANY

                                            /s/ Edwin W. Miller
                                            -----------------------------
                                            Edwin W. Miller
                                            Vice President and Treasurer

Date: February 27, 1998


                                     Page 3











                                VOTING AGREEMENT

                  VOTING AGREEMENT (the "Agreement"), dated as of February 23,
1998, between Eli Lilly and Company, an Indiana corporation (the "Stockholder"),
and Baxter International Inc., a Delaware corporation ("Baxter").

                  WHEREAS, Baxter, RHB1 Acquisition Corp., a Delaware
corporation and a wholly owned subsidiary of Baxter ("Merger Sub"), and
Somatogen, Inc., a Delaware corporation (the "Company"), propose to enter into
an Agreement and Plan of Merger (the "Merger Agreement"), providing for the
merger of the Company with and into the Merger Sub (the "Merger"), pursuant to
the terms and subject to the conditions of the Merger Agreement, and setting
forth certain representations, warranties, covenants and agreements of the
parties thereto in connection with the Merger; and

                  WHEREAS, as of the date hereof, the Stockholder owns 2,954,104
shares of Common Stock, par value $.001 per share, of the Company ("Company
Common Stock"); and

                  WHEREAS, as an inducement to Baxter's execution of the Merger
Agreement, Baxter has requested that the Stockholder agree, and the Stockholder
hereby agrees, to vote (or consent with regard to) all shares of Company Common
Stock as to which the Stockholder has voting power in favor of the Merger as
provided herein.

                  NOW, THEREFORE, in consideration of the premises and the
representations, warranties, covenants and agreements contained herein, and for
other good and valuable consideration, the receipt and sufficiency of which is
hereby acknowledged, the parties hereto, intending to be legally bound hereby,
agree as follows:

                  1. Representations of the Stockholder. The Stockholder hereby
represents and warrants to Baxter as follows:

                  (a) The Stockholder is the holder of 2,954,104 shares of
         Company Common Stock (the "Shares").










                  (b) The Stockholder does not beneficially own (as such term is
         defined in Rule 13d-3 under the Securities Exchange Act of 1934, as
         amended and the rules and regulations thereunder (the "Exchange Act"),
         any shares of Company Common Stock, other than the Shares.

                  (c) The Stockholder has the right, power and authority to
         execute and deliver this Agreement and to perform its obligations under
         this Agreement, and this Agreement has been duly executed and delivered
         by the Stockholder; and, assuming that this Agreement has been duly and
         validly authorized, executed and delivered by Baxter, this Agreement
         constitutes a valid and legally binding agreement of the Stockholder,
         enforceable in accordance with its terms, subject to bankruptcy,
         insolvency, fraudulent transfer, reorganization, moratorium and similar
         laws of general applicability relating to or affecting creditors'
         rights and to general principles of equity.

                  (d) The Shares are now and will at all times during the term
         of this Agreement be held by the Stockholder or by a nominee or
         custodian for the account of the Stockholder, free and clear of all
         pledges, liens, proxies, claims, charges, security interests,
         preemptive rights, voting trusts and any other encumbrances whatsoever
         with respect to the ownership, transfer or voting of the Shares; and
         there are no outstanding options, warrants or rights to purchase or
         acquire, or other agreements relating to, the Shares other, than this
         Agreement.

The representations and warranties contained herein shall be made as of the date
hereof and as of each date from the date hereof through and including the date
that the Merger is consummated.

                  2. Agreement to Vote Shares. The Stockholder agrees to: (a)
appear, or cause the record holder of the Shares on the applicable record date
(the "Record Holder") to appear, at any annual or special meeting of the
stockholders of the Company for the purpose of obtaining a quorum and (b) vote,
and cause the Record Holder to vote, the Shares and any New Shares (as defined
in Section 7 below) (i) in favor of adoption and approval of the Merger
Agreement and the Merger (and each other action and transaction contemplated by
the Merger Agreement and this Agreement) at every meeting of the stockholders of
the Company at which such matters are considered and at every adjournment
thereof and (ii) against any action or proposal that would compete with or could
serve to materially interfere with, delay, discourage, adversely affect or
inhibit the timely consummation of the Merger. The Stockholder agrees to
deliver to Baxter upon request a proxy for any

                                        2









such stockholder meeting, which proxy shall be coupled with an interest and
irrevocable to the extent permitted under Delaware law, with the total number of
the Stockholder's Shares and any New Shares correctly indicated thereon.

                  3. No Proxy Solicitations. The Stockholder agrees that the
Stockholder will not, nor will the Stockholder permit any entity under its
control to, (a) solicit proxies or become a "participant" in a "solicitation"
(as such terms are defined in Regulation 14A under the Exchange Act) in
opposition to or competition with the consummation of the Merger or otherwise
encourage or assist any party in taking or planning any action which would
compete with or otherwise could serve to materially interfere with, delay,
discourage, adversely affect or inhibit the timely consummation of the Merger in
accordance with the terms of the Merger Agreement, (b) directly or indirectly
encourage, initiate or cooperate in a stockholders' vote or action by consent of
the Company's stockholders in opposition to or in competition with the
consummation of the Merger or (c) become a member of a "group" (as such term is
used in Section 13(d) of the Exchange Act) with respect to any voting
securities of the Company for the purpose of opposing or competing with the
consummation of the Merger.

                  4. Transfer and Encumbrance. On or after the date hereof, the
Stockholder agrees not to voluntarily transfer, sell, offer, assign, pledge or
otherwise dispose of or encumber ("Transfer") any of the Shares or New Shares
prior to the earlier of (a) the effective date of the Merger or (b) the date
this Agreement shall be terminated in accordance with its terms. In furtherance
of this Agreement, concurrently herewith the Stockholder shall and hereby does
authorize the Company's transfer agent that there is a stop transfer order with
respect to the Shares and that this Agreement places limitations on the voting
and transfer of such shares.

                  5. Additional Purchases. The Stockholder agrees that in the
event (i) any stock dividend, stock split, recapitalization, reclassification,
combination or exchange of shares of capital stock of the Company on, of or
affecting the Shares of the Stockholder, (ii) the Stockholder purchases or
otherwise acquires beneficial ownership of any shares of Company Common Stock
after the execution of this Agreement or (iii) the Stockholder voluntarily
acquires the right to vote or share in the voting of any shares of Company
Common Stock other than the Shares (collectively, "New Shares"), the Stockholder
agrees to vote such New Shares in the same manner as the Shares and to notify
Baxter and then deliver promptly to Baxter upon request of Baxter an irrevocable
proxy with respect to such New Shares. The Stockholder also agrees that any New
Shares acquired or purchased by it shall be subject to the terms of this
Agreement to the same extent as if they constituted

                                        3









Shares.

                  6. Specific Performance. Each party hereto acknowledges that
it will be impossible to measure in money the damage to the other party if the
party hereto fails to comply with any of the obligations imposed by this
Agreement, that every such obligation is material and that, in the event of any
such failure, the other party will not have an adequate remedy at law or
damages. Accordingly, each party hereto agrees that injunctive relief or other
equitable remedy, in addition to remedies at law or damages, is the appropriate
remedy for any such failure and will not oppose the granting of such relief on
the basis that the other party has an adequate remedy at law. Each party hereto
agrees that it will not seek, and agrees to waive any requirement for, the
securing or posting of a bond in connection with any other party's seeking or
obtaining such equitable relief.

                  7. Successors and Assigns. This Agreement shall be binding
upon, inure to the benefit of, and be enforceable by the parties hereto and
their respective successors and assigns; and nothing in this Agreement, express
or implied, is intended to confer upon any other person any rights or remedies
of any nature whatsoever under or by reason of this Agreement. This Agreement
shall not be assignable without the written consent of the other party hereto,
except that Baxter may assign, in its sole discretion, all or any of its rights,
interests and obligations hereunder to Merger Sub.

                  8. Termination. This Agreement will terminate upon the
earliest to occur of (i) the effective time of the Merger, (ii) termination of
the Merger Agreement, (iii) a determination by the Board of Directors of the
Company that a Superior Competing Bid (as defined below) has been received or
(iv) September 30, 1998. For purposes of this section, a Superior Competing Bid
means a "Superior Proposal" (as defined in Section 5.3 of the Merger Agreement)
as to which the Board of Directors of the Company has determined in good faith
(based on the written advice of an independent financial advisor) that the
consideration to be received by the Stockholder has a present value that is at
least twenty-five percent greater than the present value of the consideration
that would be received by the Stockholder pursuant to the Merger.

                  9. Entire Agreement. Except for the Confidentiality Agreement,
dated February 11, 1998, by and among the Stockholder, the Company and Baxter,
this Agreement supersedes all prior agreements, written or oral, among the
parties hereto with respect to the subject matter hereof and contains the entire
agreement among the parties with respect to the subject matter hereof. This
Agreement may not


                                        4








be amended, supplemented or modified, and no provisions hereof may be modified
or waived, except by an instrument in writing signed by the parties hereto. No
waiver of any provisions hereof by any party shall be deemed a waiver of any
other provisions hereof by any such party, nor shall any such waiver be deemed a
continuing waiver of any provision hereof by such party.

                  10. Governing Law. This Agreement shall be deemed a contract
made under, and for all purposes shall be construed in accordance with, the laws
of the State of Delaware, regardless of the laws that might otherwise govern
under applicable principles of conflicts of law.

                  11. Severability. If any provision of this Agreement or the
application of such provision to any person or circumstances shall be held
invalid by a court of competent jurisdiction, the remainder of the provision
held invalid and the application of such provision to persons or circumstances,
other than the party as to which it is held invalid, shall not be affected.

                  12. Counterparts. This Agreement may be executed in one or
more counterparts, each of which shall be deemed to be an original but all of
which together shall constitute one and the same instrument.

                  13. Headings. All Section headings herein are for convenience
of reference only and are not part of this Agreement, and no construction or
reference shall be derived therefrom.

                                        5










                  IN WITNESS WHEREOF, the parties hereto have executed and
delivered this Agreement as of the date first written above.

                                            ELI LILLY AND COMPANY

                                            By:
                                               -----------------------------
                                               Edwin W. Miller
                                               Vice President and Treasurer


                                            BAXTER INTERNATIONAL INC.

                                            By:
                                               -----------------------------
                                               John F. Gaither, Jr.
                                               Corporate Vice President
                                               Corporate Development & Strategy