EXHIBIT 3.3

                         CERTIFICATE OF DETERMINATION

 
                         CERTIFICATE OF DETERMINATION
                                      OF
                     RIGHTS, PREFERENCES AND PRIVILEGES OF
                 SERIES B JUNIOR PARTICIPATING PREFERRED STOCK
                                      OF
                              MYCOGEN CORPORATION


          The undersigned, Jerry D. Caulder and Carlton J. Eibl, do hereby
certify:

          (a)  That Jerry D. Caulder is the duly elected and acting Chief
Executive Officer of  Mycogen Corporation, a California corporation (the
"Corporation") and Carlton J. Eibl is the duly elected and acting President,
Chief Operating Officer and Secretary of the Corporation.

          (b)  That none of the shares of the Series B Junior Participating
Preferred Stock have been issued.

          (c)  That pursuant to the authority conferred upon the Board of
Directors of the Corporation (the "Board") by the Articles of Incorporation of
the Corporation, the Board on October 19, 1995, adopted the following
resolutions creating a series of 200,000 shares of Preferred Stock designated as
Series B Junior Participating Preferred Stock:

     NOW, THEREFORE, BE IT RESOLVED, that pursuant to the authority granted to
     and vested in the Board in accordance with the provisions of the Articles
     of Incorporation of the Corporation, the Board hereby creates a series of
     Preferred Stock, par value $.001 per share (the "Preferred Stock"), of the
     Corporation and hereby states the designation and number of shares and
     fixes the relative rights, preferences and limitations thereof (in addition
     to the provisions set forth in the Articles of Incorporation of the
     Corporation, which are applicable to the Preferred Stock of all classes and
     series), as Series B Junior Participating Preferred Stock as set forth in
     the Certificate of  Determination, attached to the Amended and Restated
     Rights Agreement as Exhibit "A".

     RESOLVED FURTHER, that two hundred thousand (200,000) Preferred Shares be,
     as of the Effective Date of the Merger (as such term is defined in the
     Rights Agreement), initially reserved for issuance upon exercise of the
     Rights, such number to be subject to adjustment from time to time in
     accordance with the Rights Agreement.

          1.   DESIGNATION AND AMOUNT.  The shares of such series shall be
               ----------------------                                     
designated as "Series B Junior Participating Preferred Stock" (the "Series B
Preferred Stock") and the number of shares constituting the Series B Preferred
Stock shall be Two Hundred Thousand (200,000).  Such number of shares may be
increased or decreased by resolution of the Board; provided, that no decrease
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shall reduce the number of shares of Series B Preferred Stock to a number less
than the number of shares then outstanding plus the number of shares reserved
for issuance upon the exercise of outstanding options, 

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rights or warrants or upon the conversion of any outstanding securities issued
by the Corporation convertible into Series B Preferred Stock.

          2.   DIVIDENDS AND DISTRIBUTIONS.
               --------------------------- 

          (a)  Subject to the rights of the holders of any shares of any series
of Preferred Stock (or any similar stock) ranking prior and superior to the
Series B Preferred Stock with respect to dividends, the holders of shares of
Series B Preferred Stock, in preference to the holders of Common Stock, par
value $.001 per share (the "Common Stock"), of the Corporation, and of any other
junior stock, shall be entitled to receive, when, as and if declared by the
Board out of funds legally available for the purpose, quarterly dividends
payable in cash on the first day of March, June, September and December in each
year (each such date being referred to herein as a "Quarterly Dividend Payment
Date"), commencing on the first Quarterly Dividend Payment Date after the first
issuance of a share or fraction of a share of Series B Preferred Stock, in an
amount per share (rounded to the nearest cent) equal to the greater of (a) $1 or
(b) subject to the provision for adjustment hereinafter set forth, 100 times the
aggregate per share amount of all cash dividends, and 100 times the aggregate
per share amount (payable in kind) of all non-cash dividends or other
distributions, other than a dividend payable in shares of Common Stock or a
subdivision of the outstanding shares of Common Stock (by reclassification or
otherwise), declared on the Common Stock since the immediately preceding
Quarterly Dividend Payment Date or, with respect to the first Quarterly Dividend
Payment Date, since the first issuance of any share or fraction of a share of
Series B Preferred Stock.  In the event the Corporation shall at any time
declare or pay any dividend on the Common Stock payable in shares of Common
Stock, or effect a subdivision or combination or consolidation of the
outstanding shares of Common Stock (by reclassification or otherwise than by
payment of a dividend in shares of Common Stock) into a greater or lesser number
of shares of Common Stock, then in each such case the amount to which holders of
shares of Series B Preferred Stock were entitled immediately prior to such event
under clause (b) of the preceding sentence shall be adjusted by multiplying such
amount by a fraction, the numerator of which is the number of shares of Common
Stock outstanding immediately after such event and the denominator of which is
the number of shares of Common Stock that were outstanding immediately prior to
such event.

          (b)  The Corporation shall declare a dividend or distribution on the
Series B Preferred Stock as provided in paragraph (a) of this Section
immediately after it declares a dividend or distribution on the Common Stock
(other than a dividend payable in shares of Common Stock); provided that, in the
event no dividend or distribution shall have been declared on the Common Stock
during the period between any Quarterly Dividend Payment Date and the next
subsequent Quarterly Dividend Payment Date, a dividend of $1 per share on the
Series B Preferred Stock shall nevertheless be payable on such subsequent
Quarterly Dividend Payment Date.

          (c)  Dividends shall begin to accrue and be cumulative on outstanding
shares of Series B Preferred Stock from the Quarterly Dividend Payment Date next
preceding the date of issue of such shares, unless the date of issue of such
shares is prior to the record date for the first Quarterly Dividend Payment
Date, in which case dividends on such shares shall begin to accrue from the date
of issue of such shares, or unless the date of issue is a Quarterly Dividend
Payment Date or is a date after the record date for the determination of holders
of shares of Series B Preferred Stock entitled to receive a quarterly 

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dividend and before such Quarterly Dividend Payment Date, in either of which
events such dividends shall begin to accrue and be cumulative from such
Quarterly Dividend Payment Date. Accrued but unpaid dividends shall not bear
interest. Dividends paid on the shares of Series B Preferred Stock in an amount
less than the total amount of such dividends at the time accrued and payable on
such shares shall be allocated pro rata on a share-by-share basis among all such
shares at the time outstanding. The Board may fix a record date for the
determination of holders of shares of Series B Preferred Stock entitled to
receive payment of a dividend or distribution declared thereon, which record
date shall be not more than 60 days prior to the date fixed for the payment
thereof.

          3.   VOTING RIGHTS.  The holders of shares of Series B Preferred Stock
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shall have the following voting rights:

          (a)  Subject to the provision for adjustment hereinafter set forth,
each share of Series B Preferred Stock shall entitle the holder thereof to 100
votes on all matters submitted to a vote of the stockholders of the Corporation.
In the event the Corporation shall at any time declare or pay any dividend on
the Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the number of votes per share to which holders of shares of Series B
Preferred Stock were entitled immediately prior to such event shall be adjusted
by multiplying such number by a fraction, the numerator of which is the number
of shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

          (b)  Except as otherwise provided herein, in any other Certificate of
Determination creating a series of Preferred Stock or any similar stock, or by
law, the holders of shares of Series B Preferred Stock and the holders of shares
of Common Stock and any other capital stock of the Corporation having general
voting rights shall vote together as one class on all matters submitted to a
vote of stockholders of the Corporation.

          (c)  Except as set forth herein, or as otherwise provided by law,
holders of Series B Preferred Stock shall have no special voting rights and
their consent shall not be required (except to the extent they are entitled to
vote with holders of Common Stock as set forth herein) for taking any corporate
action.

          4.   CERTAIN RESTRICTIONS.
               -------------------- 

          (a)  Whenever quarterly dividends or other dividends or distributions
payable on the Series B Preferred Stock as provided in Section 2 are in arrears,
thereafter and until all accrued and unpaid dividends and distributions, whether
or not declared, on shares of Series B Preferred Stock outstanding shall have
been paid in full, the Corporation shall not:

               (i)  declare or pay dividends, or make any other distributions,
on any shares of stock ranking junior (either as to dividends or upon
liquidation, dissolution or winding up) to the Series B Preferred Stock;

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               (ii)   declare or pay dividends, or make any other distributions,
on any shares of stock ranking on a parity (either as to dividends or upon
liquidation, dissolution or winding up) with the Series B Preferred Stock,
except dividends paid ratably on the Series B Preferred Stock and all such
parity stock on which dividends are payable or in arrears in proportion to the
total amounts to which the holders of all such shares are then entitled;

               (iii)  redeem or purchase or otherwise acquire for consideration
shares of any stock ranking junior (either as to dividends or upon liquidation,
dissolution or winding up) to the Series B Preferred Stock, provided that the
Corporation may at any time redeem, purchase or otherwise acquire shares of any
such junior stock in exchange for shares of any stock of the Corporation ranking
junior (either as to dividends or upon dissolution, liquidation or winding up)
to the Series B Preferred Stock; or

               (iv)   redeem or purchase or otherwise acquire for consideration
any shares of Series B Preferred Stock, or any shares of stock ranking on a
parity with the Series B Preferred Stock, except in accordance with a purchase
offer made in writing or by publication (as determined by the Board) to all
holders of such shares upon such terms as the Board, after consideration of the
respective annual dividend rates and other relative rights and preferences of
the respective series and classes, shall determine in good faith will result in
fair and equitable treatment among the respective series or classes.

          (b)  The Corporation shall not permit any subsidiary of the
Corporation to purchase or otherwise acquire for consideration any shares of
stock of the Corporation unless the Corporation could, under paragraph (a) of
this Section 4, purchase or otherwise acquire such shares at such time and in
such manner.

          5.   RE-ACQUIRED SHARES.  Any shares of Series B Preferred Stock
               ------------------                                         
purchased or otherwise acquired by the Corporation in any manner whatsoever
shall be retired and canceled promptly after the acquisition thereof.  All such
shares shall upon their cancellation become authorized but unissued shares of
Preferred Stock and may be reissued as part of a new series of Preferred Stock
subject to the conditions and restrictions on issuance set forth herein, in the
Articles of Incorporation, or in any other Certificate of Determination creating
a series of Preferred Stock or any similar stock or as otherwise required by
law.

          6.   LIQUIDATION, DISSOLUTION OR WINDING UP.  Upon any liquidation,
               --------------------------------------                        
dissolution or winding up of the Corporation, no distribution shall be made (1)
to the holders of shares of stock ranking junior (either as to dividends or upon
liquidation, dissolution or winding up) to the Series B Preferred Stock unless,
prior thereto, the holders of shares of Series B Preferred Stock shall have
received $100 per share, plus an amount equal to accrued and unpaid dividends
and distributions thereon, whether or not declared, to the date of such payment,
provided that the holders of shares of Series B Preferred Stock shall be
entitled to receive an aggregate amount per share, subject to the provisions for
adjustment hereinafter set forth, equal to 100 times the aggregate amount to be
distributed per share to holders of shares of Common Stock, or (2) to the
holders of shares of stock ranking on a parity (either as to dividends or upon
liquidation, dissolution or winding up) with the Series B Preferred Stock,
except distributions made ratably on the Series B Preferred Stock and all such
parity stock in proportion to the total amounts to which the holders of all such
shares are entitled upon such liquidation, dissolution or 

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winding up. In the event the Corporation shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision or combination or consolidation of the outstanding shares of Common
Stock (by reclassification or otherwise than by payment of a dividend in shares
of Common Stock) into a greater or lesser number of shares of Common Stock, then
in each such case the aggregate amount to which holders of shares of Series B
Preferred Stock were entitled immediately prior to such event under the proviso
in clause (1) of the preceding sentence shall be adjusted by multiplying such
amount by a fraction, the numerator of which is the number of shares of Common
Stock outstanding immediately after such event and the denominator of which is
the number of shares of Common Stock that were outstanding immediately prior to
such event.

          7.   CONSOLIDATION, MERGER, ETC.  In case the Corporation shall enter
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into any consolidation, merger, combination or other transaction in which the
shares of Common Stock are exchanged for or changed into other stock or
securities, cash and/or any other property, then in any such case each share of
Series B Preferred Stock shall at the same time be similarly exchanged or
changed into an amount per share, subject to the provision for adjustment
hereinafter set forth, equal to 100 times the aggregate amount of stock,
securities, cash and/or any other property (payable in kind), as the case may
be, into which or for which each share of Common Stock is changed or exchanged.
In the event the Corporation shall at any time declare or pay any dividend on
the Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the amount set forth in the preceding sentence with respect to the
exchange or change of shares of Series B Preferred Stock shall be adjusted by
multiplying such amount by a fraction, the numerator of which is the number of
shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

          8.   NO REDEMPTION.  The shares of Series B Preferred Stock shall not
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be redeemable.

          9.   RANK.  The Series B Preferred Stock shall rank, with respect to
               ----                                                           
the payment of dividends and the distribution of assets, junior to all series of
the Corporation's Preferred Stock.

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          10.  AMENDMENT.  The Articles of Incorporation of the Corporation
               ---------                                                   
  shall not be amended in any manner which would materially alter or change the
  powers, preferences or special rights of the Series B Preferred Stock so as to
  effect them adversely without the affirmative vote of the holders of at least
  a majority of the outstanding shares of Series B Preferred Stock, voting
  together as a single class.

          We further declare under penalty of perjury that the matters set forth
  in the foregoing Certification of Determination are true and correct of our
  own knowledge.

  Executed at San Diego, California on October 19, 1995.


                                                     /s/ Jerry D. Caulder
                                                     --------------------
                                                     Jerry D. Caulder,
                                                     Chief Executive Officer


                                                     /s/ Carlton J. Eibl
                                                     -------------------------
                                                     Carlton J. Eibl, President,
                                                     Chief Operating Officer    
                                                     and Secretary

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