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                                                                     Exhibit 4.5


                                   Ecogen Inc.
                             1999 STOCK OPTION PLAN




1.    Purpose.

      The purpose of this plan (the "Plan") is to secure for Ecogen Inc. (the
"Company") and its stockholders the benefits arising from capital stock
ownership by employees, advisors, consultants, and members of the Board of
Directors of the Company and its parent and subsidiary corporations, if any, who
are expected to contribute to the Company's future growth and success.

2.    Types of Options and Administration.

            (a) Types of Options. Options granted pursuant to the Plan shall be
authorized by action of the Board of Directors of the Company (or a Committee
designated by the Board of Directors) and may be either incentive stock options
("Incentive Stock Options") meeting the requirements of Section 422 of the
Internal Revenue Code of 1986, as amended (the "Code"), or non-statutory options
which are not intended to meet the requirements of Code Section 422.

            (b) Administration.

                  (i) Board of Directors. The Plan will be administered by the
Board of Directors of the Company, whose construction and interpretation of the
terms and provisions of the Plan shall be final and conclusive. The Board of
Directors may in its sole discretion grant options to purchase shares of the
Company's Common Stock, par value $.01 per share ("Common Stock"), and authorize
the Company to issue shares upon exercise of such options as provided in the
Plan. The Board shall have the authority, subject to the express provisions of
the Plan, to construe the respective option agreements and the Plan, to
prescribe, amend and rescind rules and regulations relating to the Plan, to
determine the terms and provisions of the respective option agreements, which
need not be identical, to advance the lapse of any waiting or installment
periods and exercise dates, and to make all other determinations in the judgment
of the Board of Directors necessary or desirable for the administration of the
Plan. The Board of Directors may correct any defect or supply any omission or
reconcile any inconsistency in the Plan or in any option agreement in the manner
and to the extent it shall deem expedient to carry the Plan into effect and it
shall be the sole and final judge of such expediency. No director shall be
liable for any action or determination taken or made under or with respect to
the Plan or to the grant of any option in good faith.

                  (ii) Committee. The Board of Directors may, to the full extent
permitted by law, delegate any or all of its powers under the Plan to a
committee (the "Committee") of two or more directors each of whom is a
Non-Employee Director (as hereinafter defined), and if the Committee is so
appointed all references to the Board of Directors
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in the Plan shall mean and relate to such Committee. For the purposes of the
Plan, a director or member of such Committee shall be deemed to be a
"Non-Employee Director" only if such person qualifies as a "Non-Employee
Director" within the meaning of paragraph (b)(3) of Rule 16b-3 promulgated under
the Securities Exchange Act of 1934, as amended (or any successor rule).

                  (iii) Chief Executive Officer. Notwithstanding anything
contained in this Section 2 to the contrary, the Board of Directors may, to the
full extent permitted by law, delegate the power under the Plan to grant options
to persons who are, at the time of grant, non-officer employees, advisors and
consultants of the Company or of any Parent Corporation or Subsidiary (provided,
however, that no such person at the time of grant is subject to Section 16 of
the Securities Exchange Act of 1934, as amended (the "Exchange Act") in
accordance with Rule 16a-2 promulgated under the Exchange Act), to the Chief
Executive Officer, and if the Chief Executive Officer is so appointed, to the
extent necessary to give effect to such appointment, all references to the Board
of Directors in the Plan shall mean and relate to such Chief Executive Officer.

3.    Eligibility.

      Options shall be granted only to persons who are, at the time of grant,
employees, advisors, consultants, or directors (provided, in the case of
Incentive Stock Options, such directors are then also employees) of the Company
or of any Parent Corporation or Subsidiary (as defined in Section 19 hereof). A
person who has been granted an option may, if he or she is otherwise eligible,
be granted an additional option or options if the Board of Directors shall so
determine.

4.    Stock Subject to Plan.

      Subject to adjustment as provided in Sections 15 and 16 below, the maximum
number of shares of Common Stock of the Company which may be issued and sold
pursuant to options granted under the Plan is 1,500,000 shares. Such shares may
be authorized and unissued shares or may be shares issued and thereafter
acquired by the Company. If an option granted under the Plan shall expire or
terminate for any reason without having been exercised in full, the unpurchased
shares subject to such option shall again be available for subsequent option
grants under the Plan. Stock issuable upon exercise of an option granted under
the Plan may be subject to transfer restrictions, repurchase rights or other
restrictions as shall be determined by the Board of Directors.

5.    Option Agreements.

      As a condition to the grant of an option under the Plan, each recipient of
an option shall execute an option agreement not inconsistent with the Plan in
such form as the Board of Directors shall determine at the time such option is
authorized to be granted. Such agreements need not be identical but shall comply
with, and be subject to, the terms and conditions set forth herein.
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6.    Purchase Price.

            (a) The purchase price per share of Common Stock deliverable upon
the exercise of an option shall be not less than the fair market value of the
Common Stock as determined by the Board of Directors on the date such option is
authorized to be granted.

            (b) Payment of the exercise price of an option shall be in cash or,
in the sole discretion of the Board of Directors, in capital stock of the
Company, by the surrender of other options to purchase capital stock of the
Company or by any other lawful means.

7.    Option Term.

      Each option and all rights thereunder shall expire on such date as the
Board of Directors shall determine on the date such option is authorized to be
granted, but in no event after the expiration of ten years from the day on which
the option is granted (or five years in the case of options described in
paragraph (b) of Section 11), and shall be subject to earlier termination as
provided in the Plan. Notwithstanding the foregoing, except as provided under or
pursuant to the Code with respect to Incentive Stock Options, if at any time
during the last six (6) months of the term of any option granted under the Plan,
the holder thereof is precluded from selling shares of Common Stock underlying
such option solely by reason of the application to such optionee of the
Company's "Material Inside Information and Insider Trading Policy" (or similar
successor policy), the term of such option shall be deemed automatically
extended by a period equal to six (6) months beginning with the first day during
which such optionee shall no longer be so precluded.

8.    Exercise of Options.

Each option granted under the Plan shall be exercisable either in full or in
installments at such time or times during such period as shall be set forth in
the agreement evidencing such option; provided, however, that, subject to
Section 7, (i) no option granted under the Plan shall have a term in excess of
ten years from the date of grant (or five years in the case of options described
in paragraph (b) of Section 11) and (ii) the periods of time following the
optionee's cessation of employment with the Company or service as an advisor,
consultant, or Outside Director of the Company, or the optionee's death or
disability, during which an option may be exercised, as provided in paragraphs
(a), (b) and (c) of Section 10, shall not be included for purposes of
determining the number of shares of Common Stock with respect to which an option
granted under the Plan may be exercised.

9.    Transfer Restrictions.

      Except as otherwise approved by the Board of Directors, no option granted
under the Plan shall be assignable or transferable by the person to whom it is
granted, either voluntarily or by operation of law, except by will or the laws
of descent and distribution. Except as otherwise approved by the Board of
Directors and subject to the preceding sentence, during the life of the
recipient, the option shall be exercisable only by or on behalf of such person.
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10.   Effect of Termination of Employment.

      Notwithstanding anything contained in this Plan to the contrary, no option
may be exercised unless, at the time of such exercise, the optionee is, and has
been continuously since the date of grant of his or her option, employed by one
or more of the Company, a Parent Corporation or a Subsidiary, except that if and
to the extent the option agreement or instrument so provides:

            (a) the option may be exercised within the period of three months
after the date the optionee ceases to be employed by or to serve as an advisor,
consultant, or Outside Director of the Company, a Parent Corporation or a
Subsidiary(or within such lesser period as may be specified in the option
agreement or instrument) for any reason other than death or disability;

            (b) if the optionee dies while in the employ of or serving as an
advisor, consultant, or Outside Director of the Company, a Parent Corporation or
a Subsidiary or within three months after the optionee ceases to be such an
employee, advisor, consultant, or director, the option may be exercised by the
person to whom it is transferred by will or the laws of descent and distribution
within the period of one year after the date of death (or within such lesser
period as may be specified in the option agreement or instrument); and

            (c) if the optionee becomes disabled (within the meaning of Section
22(e)(3) of the Code) while in the employ of or while serving as an advisor,
consultant, or Outside Director of the Company, a Parent Corporation or a
Subsidiary, the option may be exercised within the period of one year after the
date the optionee ceases to be an employee, advisor, consultant, or director of
any of the foregoing entities because of such disability (or within such lesser
period as may be specified in the option agreement or instrument); provided,
however, that in no event may any option be exercised after the expiration date
of the option. For all purposes of the Plan and any option granted hereunder,
"employment" shall be defined in accordance with the provisions of Section
1.421-7(h) of the Income Tax Regulations (or any successor regulations).

11.   Incentive Stock Options.

      Options granted under the Plan which are intended to be Incentive Stock
Options shall be specifically designated as Incentive Stock Options and shall be
subject to the following additional terms and conditions:

            (a) Dollar Limitation. The aggregate fair market value (determined
as of the respective date or dates of the grant) of the Common Stock with
respect to which Incentive Stock Options granted to any employee under the Plan
(and under any other incentive stock option plans of the Company, and any Parent
Corporation and Subsidiary) are exercisable for the first time shall not exceed
$100,000 in any one calendar year. In the event that Section 422 of the Code is
amended to alter the limitation set forth therein so that following such
amendment such
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limitation shall differ from the limitation set forth in this paragraph (a), the
limitation of this paragraph (a) shall be automatically adjusted accordingly.

            (b) 10% Stockholder. If any employee to whom an Incentive Stock
Option is to be granted under the Plan is at the time of the grant of such
option the owner of stock possessing more than 10% of the total combined voting
power of all classes of stock of the Company or of any Parent Corporation or any
Subsidiary, then the following special provisions shall be applicable to the
Incentive Stock Option granted to such individual:

                  (i) The purchase price per share of the Common Stock subject
to such Incentive Stock Option shall not be less than 110% of the fair market
value of one share of Common Stock at the time of grant; and

                  (ii) The option exercise period shall not exceed five years
from the date of grant.

Except as modified by the preceding provisions of this Section 11, all the
provisions of the Plan shall be applicable to Incentive Stock Options granted
hereunder.

12. Annual Automatic Grants of Options to Outside Directors.

            (a) Annual Automatic Grants of Options to Outside Directors. Each
director of the Company who is not an employee of the Company or of any Parent
Corporation or Subsidiary (each, an "Outside Director") shall be granted under
the Plan (i) on the date of his or her first election to the Board of Directors
of the Company, non-statutory options to purchase up to 10,000 shares of Common
Stock and (ii) on the date of each annual meeting of the Company's stockholders
(beginning with the Company's Annual Meeting of Stockholders in 2000) at which
such Outside Director is re-elected to the Board of Directors, non-statutory
options to purchase up to 10,000 shares of Common Stock.

            (b) Terms and Conditions of Options. Any option granted to an
Outside Director pursuant to this Section 12 shall be exercisable over a two
year period, one half on each of the first two anniversaries of the date of
grant, in each case at a purchase price equal to the fair market value of such
Common Stock, as defined in Section 6 above, on the date of grant. Each such
option shall expire ten years after the date of grant and shall be subject to
earlier termination as provided in the Plan. Notwithstanding the foregoing, if
at any time during the last six (6) months of the term of any option granted
pursuant to this Section 12, the holder thereof is precluded from selling shares
of Common Stock underlying such option solely by reason of the application to
such Outside Director of the Company's "Material Inside Information and Insider
Trading Policy" (or any similar successor policy), the term of such option shall
be deemed automatically extended by a period equal to six (6) months beginning
with the first day during which such Outside Director shall no longer be so
precluded.

            (c) Plan Applicable. Except as set forth in this Section 12, all the
provisions of the Plan shall be applicable to options granted to Outside
Directors hereunder.
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13.   General Restrictions.

            (a) Investment Representations. The Company may require any person
to whom an option is granted, as a condition of exercising such option, to give
written assurances in substance and form satisfactory to the Company to the
effect that such person is acquiring the Common Stock subject to the option for
his own account for investment and not with any present intention of selling or
otherwise distributing the same, and to such other effects as the Company deems
necessary or appropriate in order to comply with federal and applicable state
securities laws.

            (b) Compliance With Securities Laws. Each option shall be subject to
the requirement that, if at any time counsel to the Company shall determine that
the listing, registration or qualification of the shares subject to such option
upon any securities exchange or under any state or federal law, or the consent
or approval of any governmental or regulatory body, is necessary as a condition
of, or in connection with, the issuance or purchase of shares thereunder, such
option may not be accepted or exercised in whole or in part unless such listing,
registration, qualification, consent or approval shall have been effected or
obtained on conditions acceptable to the Board of Directors. Nothing herein
shall be deemed to require the Company to apply for or to obtain such listing,
registration or qualification.

14.   Rights as a Stockholder.

The holder of an option shall have no rights as a stockholder with respect to
any shares covered by the option until the date of issue of a stock certificate
to him or her for such shares. Except as otherwise expressly provided in the
Plan, no adjustment shall be made for dividends or other rights for which the
record date is prior to the date such stock certificate is issued.

15.   Recapitalization.

      In the event that the outstanding shares of Common Stock of the Company
are changed into or exchanged for a different number or kind of shares or other
securities of the Company by reason of any recapitalization, reclassification,
stock split, stock dividend, combination or subdivision, appropriate adjustment
shall be made in the number and kind of shares available under the Plan and
under any options granted under the Plan. Such adjustment to outstanding options
shall be made without change in the total price applicable to the unexercised
portion of such options, and a corresponding adjustment in the applicable option
price per share shall be made. No such adjustment shall be made which would,
within the meaning of any applicable provisions of the Code, constitute a
modification, extension or renewal of any option or a grant of additional
benefits to the holder of an option.

16.   Reorganization or Change in Control of the Company.

            (a) Reorganization. In case (i) the Company is merged or
consolidated with another corporation and the Company is not the surviving
corporation, (ii) all or substantially all of the assets or more than 50% of the
outstanding voting stock of the Company is acquired by any other corporation or
(iii) of a reorganization or liquidation of the Company, the Board of Directors
of the Company, or the board of directors of any corporation assuming the
obligations
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of the Company, shall, as to outstanding options, either (x) make appropriate
provision for the protection of any such outstanding options by the substitution
on an equitable basis of appropriate stock of the Company, or of the merged,
consolidated or otherwise reorganized corporation which will be issuable in
respect of the shares of Common Stock of the Company, provided that no
additional benefits shall be conferred upon optionees as a result of such
substitution, and the excess of the aggregate fair market value of the shares
subject to the options immediately after such substitution over the purchase
price thereof is not more than the excess of the aggregate fair market value of
the shares subject to the option immediately before such substitution over the
purchase price thereof, or (y) upon written notice to the optionees, provide
that all unexercised options must be exercised within a specified number of days
of the date of such notice or they will be terminated. In any such case, the
Board of Directors may, in its discretion, accelerate the exercise dates of
outstanding options; provided, however, that paragraph (b) below shall govern
acceleration of options with respect to the events described in clauses (i),
(ii) and (iii) of such paragraph.

            (b) Change in Control. In case of (i) any merger or consolidation
(an "Event") involving the Company, if the shareholders of the Company
immediately before such Event do not own, directly or indirectly, immediately
following such Event, more than fifty percent (50%) of the combined voting power
of the outstanding voting securities of the corporation resulting from such
Event in substantially the same proportion as their ownership of the shares of
Common Stock immediately before such Event; (ii) any sale, lease, license,
exchange or other transfer (in one transaction or a series of related
transactions) of all, or substantially all, of the business and/or assets of the
Company or assets representing over 50% of the operating revenue of the Company;
or (iii) any person (as such term is used in Sections 13(d) and 14(d) of the
Exchange Act) who was not, on December 2, 1998, a "controlling person" (as
defined in Rule 405 under the Securities Act of 1933, as amended) (a
"Controlling Person") of the Company shall become (x) the beneficial owner
(within the meaning of Rule 13d-3 under the Exchange Act) of over 50% of the
combined voting power of the Company's then outstanding voting securities
entitled to vote generally or (y) a Controlling Person of the Company, all
outstanding Options, regardless of the date of such Options, shall immediately
become exercisable with respect to 100% of the Common Stock subject to such
Options.

17.   No Special Employment Rights.

      Nothing contained in the Plan or in any option granted under the Plan
shall confer upon any option holder any right with respect to the continuation
of his or her employment by the Company (or any Parent Corporation or
Subsidiary) or interfere in any way with the right of the Company (or any Parent
Corporation or Subsidiary), subject to the terms of any separate employment
agreement to the contrary, at any time to terminate such employment or to
increase or decrease the compensation of the option holder from the rate in
existence at the time of the grant of an option. Whether an authorized leave of
absence, or absence in military or government service, shall constitute
termination or cessation of employment for purposes of this Plan shall be
determined by the Board of Directors.

18.   Other Employee Benefits.
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      The amount of any compensation deemed to be received by an employee as a
result of the exercise of an option or the sale of shares received upon such
exercise will not constitute "earnings" with respect to which any other employee
benefits of such employee are determined, including without limitation benefits
under any pension, profit sharing, life insurance or salary continuation plan.

19.   Definition of Subsidiary and Parent Corporation.

            (a) Subsidiary. The term "Subsidiary" as used in the Plan shall mean
any corporation in an unbroken chain of corporations beginning with the Company
if each of the corporations other than the last corporation in the unbroken
chain owns stock possessing 50% or more of the total combined voting power of
all classes of stock in one of the other corporations in such chain. For
purposes of grants of non-statutory stock options only, the term "Subsidiary"
shall also mean any partnerships or limited partnerships for which the Company
or any Subsidiary controls 50% or more of the voting power of such partnership
or limited partnership, or any corporation in an unbroken chain of Subsidiaries
if each of the Subsidiaries other than the last Subsidiary in the unbroken chain
either owns stock possessing 50% or more of the total combined voting power of
all classes of stock in one of the other corporations or controls 50% or more of
the voting power of any such partnership or limited partnership in such chain.

            (b) Parent Corporation. The term "Parent Corporation" as used in the
Plan shall mean any corporation (other than the Company) in an unbroken chain of
corporations ending with the Company if each of the corporations other than the
Company owns stock possessing 50% or more of the combined voting power of all
classes of stock in one of the other corporations in such chain.

20.   Amendment of the Plan.

The Board of Directors may at any time and from time to time modify, amend or
terminate the Plan in any respect, except to the extent stockholder approval is
required by law. The termination or any modification or amendment of the Plan
shall not, without the consent of an optionee, affect his or her rights under an
option previously granted to him or her. With the consent of the optionee
affected, the Board of Directors may amend outstanding option agreements in a
manner not inconsistent with the Plan. The Board of Directors shall have the
right to amend or modify the terms and provisions of the Plan and of any
outstanding Incentive Stock Options granted under the Plan to the extent
necessary to qualify any or all such options for such favorable federal income
tax treatment (including deferral of taxation upon exercise) as may be afforded
incentive stock options under Section 422 of the Code.

21.   Withholding.

      The Company's obligation to deliver shares upon the exercise of any option
granted under the Plan shall be subject to the optionee's satisfaction of all
applicable federal, state and local income and employment tax withholding
requirements.
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22.   Effective Date and Duration of the Plan.

            (a) Effective Date. The Plan shall become effective when adopted by
the Board of Directors and approved by the Company's stockholders and shall not
be effective unless and until so adopted and approved. Upon the effectiveness of
the Plan, additional grants of options may not be made under the Company's 1998
Stock Option Plan.

            (b) Termination. Unless earlier terminated by the Board of
Directors, the Plan shall terminate upon the earlier of (i) the close of
business on March 10, 2009 or (ii) the date on which all shares available for
issuance under the Plan shall have been issued pursuant to the exercise or
cancellation of options granted under the Plan. If the date of termination is
determined under (i) above, then options outstanding on such date shall continue
to have force and effect in accordance with the provisions of the instruments
evidencing such options.


                                    Adopted on December 2, 1998 by the Board of
                                    Directors of Ecogen Inc.; amended on June
                                    22, 1999 (no shareholder action required);
                                    and further amended on December 9, 1999 (no
                                    shareholder action required).