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                                  EXHIBIT 10.1
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                              MYCOGEN CORPORATION
                             1992 STOCK OPTION PLAN

                PLAN AMENDMENT EFFECTIVE AS OF FEBRUARY 1, 1995
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          The Mycogen Corporation 1992 Stock Option Plan (the "Plan") is hereby
amended (the "Plan Amendment"), effective as of the 1st day of February, 1995,
as follows:

          1.  Article One, Section V.A of the Plan is hereby amended in its
entirety to read as follows:

          A.  Shares of the Company's Common Stock shall be issuable under the
     Plan, and such shares may be obtained from either the Company's authorized
     but unissued shares of Common Stock or from shares of Common Stock
     reacquired by the Company and held as treasury shares.  The aggregate
     number of shares available for issuance over the term of the Plan shall not
     exceed 5,566,719 shares of Common Stock/1/ subject to adjustment from time
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     to time in accordance with the provisions of this Section V.  To the extent
     one or more outstanding options under the 1983 Plan which have been
     incorporated into this Plan are subsequently exercised, the number of
     shares issued with respect to each such option shall reduce, on a share-
     for-share basis, the number of shares available for issuance under this
     Plan

          2.  New Section III.E is hereby added to Article Four of the Plan to
read as follows:

          As of February 1, 1995, the Board authorized an additional 1,000,000-
     share increase to the number of shares of Common Stock available for
     issuance over the term of the Plan.  However, no option granted on the
     basis of such share increase shall become exercisable, in whole or in part,
     unless and until the Corporation's stockholders approve the increase.  If
     such stockholder approval is not obtained at the 1995 Annual Stockholders
     Meeting, then any options previously granted on the basis of the 1,000,000-
     share increase shall terminate, and no further options based on such
     increase shall be granted.  All outstanding options under the Plan which
     have NOT been granted on the basis of the 1,000,000-share increase shall
     remain outstanding in accordance with the terms and provisions of the
     agreements evidencing those grants, whether or not stockholder approval of
     the share increase is obtained.  Subject to the foregoing limitations, the
     Plan Administrator may grant options under the Plan at any time before the
     date fixed herein for the termination of the Plan.

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/1/  Includes the 1,000,000-share increase approved by the Board as of 
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February 1, 1995, subject to approval by the Company's stockholders at the 1995
Annual Stockholders Meeting.
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          2.   All capitalized terms in this Plan Amendment shall have the
meanings assigned to such terms in the Plan.  To the extent that there is a
conflict between the provisions of the Plan and the provisions of this Plan
Amendment, the provisions of this Plan Amendment shall take precedence.

          3.   Except as modified by this Plan Amendment, the terms and
provisions of the Plan shall continue in full force and effect.

          IN WITNESS WHEREOF, Mycogen Corporation has caused this Plan Amendment
to be executed on its behalf by its duly-authorized officer as of the 1st day of
February, 1995.


                              MYCOGEN CORPORATION


                              By: /s/ JERRY CAULDER
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                                    Jerry Caulder

                              Title:  Chairman and
                                      Chief Executive Officer