AMENDMENT NO. 2 TO LOAN AGREEMENT

This Amendment No. 2 to Loan Agreement ("Amendment") is made as of October 1, 
1997 between Mycogen Corporation, a California corporation (the "Lender"), and 
Dow AgroSciences LLC, formerly known as DowElanco LLC, a Delaware limited 
liability company (the "Borrower") (together, the "parties").

WHEREAS, Lender and Borrower are parties to that certain Loan Agreement dated 
as of April 1, 1997, as amended by Amendment No. 1 as of April 6, 1998 (the 
"Agreement"); and

WHEREAS, the parties wish to amend the Agreement;

NOW THEREFORE, the parties hereto have agreed and do hereby agree to amend the 
Agreement as follows:

1.   Section 1.2 Repayment is hereby deleted in its entirety and replaced 
with the following:

     1.2 Repayment

         (a)  The unpaid principal amount of each Advance shall be due and 
              payable on the Repayment Date.

         (b)  Interest on the unpaid principal amount of the Loan is due and 
              payable as it accrues on the first Business Day of each 
              calendar quarter until December 31, 1997; thereafter, interest 
              on the unpaid principal amount of the Loan shall be capitalized 
              and added to the unpaid principal amount of the Loan on the 
              first Business Day of each month. Notwithstanding the 
              foregoing, all accrued and unpaid interest is due and payable 
              on the Repayment Date.

         (c)  Repayment may be made at any time, provided that the final 
              repayment be made on or prior to the Repayment Date. Borrower 
              must receive Lender's request for repayment by 9:00 a.m. 
              Eastern Standard Time on any Business Day if repayment is to be 
              made that day.

2.   Section 1.5 Interest is hereby deleted in its entirety and replaced with 
the following:

     1.5 Interest

         (a)  From October 1, 1997 until the Repayment Date, the Loan shall 
              bear interest at a rate equal to LIBID, as defined below, minus 
              0.25%.


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          (b)  "LIBID" means LIBOR minus 0.125%.  From October 1, 1997 until 
               December 31, 1997, "LIBOR" means the rate of deposits in U.S. 
               dollars for a period of three months which appears on the 
               Telerate page 3750 as of 11:00 a.m., London time, on the date 
               that is two Business days prior to the first day of the 
               Interest Period.  Effective January 1, 1998, "LIBOR" means the 
               rate for deposits in U.S. dollars for a period of one month 
               which appears on the Telerate Page 3750 as of 11:00 a.m., 
               London time, on the date that is two Business Days prior to 
               the first date of the Interest Period.  Interest accrues on 
               the unpaid principal amount of each Advance from the date of
               each Advance and is payable in accordance with Section 1.2.

          (c)  The Interest Rate for each Interest Period is calculated by 
               Lender prior to each Interest Period.  Such calculation is 
               conclusive and binding absent manifest error.

          (d)  Interest is calculated on the basis of a 360-day year for 
               actual days occurring during the Interest Period.

          (e)  "Interest Period" means each calendar quarter, or part of each 
               calendar quarter, during which the Loan or any Advance is 
               outstanding between the date of this Amendment and December 
               31, 1997.  Thereafter, "Interest Period" means the period 
               commencing on the first Business Day of each month and ending 
               on the day immediately preceding the first Business Day of 
               the succeeding month.

     All other terms and conditions of the Agreement shall remain in full
     force and effect.


IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly 
executed on the date first written above.

LENDER:                                  BORROWER:
                                         
Mycogen Corporation                      Dow AgroSciences LLC           
                                         
                                         
By:  /s/ J.A. Baumker                    By:  /s/ Sean S. Skinner       
   ----------------------------             ----------------------------
Printed:  J.A. Baumker                   Printed:  Sean S. Skinner      
        -----------------------                  -----------------------
Title:  CEO                              Title:  Treasurer              
      -------------------------                -------------------------
Date:  4/15/98                           Date:  4/13/98                 
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