Document:

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                                                                    EXHIBIT 10 A

                               SEVERANCE AGREEMENT

         THIS SEVERANCE AGREEMENT (this "Agreement"), dated as of September 20,
1999, by and between the Dexter Corporation, a Connecticut corporation (the
"Company"), and K. Grahame Walker (the "Executive").

                                   WITNESSETH:

         WHEREAS, the Executive is a senior executive or key employee of the
Company and has made and is expected to continue to make major contributions to
the short and long-term profitability, growth and financial strength of the
Company;

         WHEREAS, the Company recognizes that, as is the case for most publicly
held companies, the possibility of a Change in Control exists;

         WHEREAS, the Company desires to assure itself of both present and
future continuity of management and desires to establish certain minimum
severance benefits for certain of its senior executive officers and other key
employees, including the Executive, applicable in the event of a Change in
Control;

         WHEREAS, the Company wishes to ensure that its senior executives and
other key employees are not practically disabled from discharging their duties
in respect of a proposed or actual transaction involving a Change in Control;

         WHEREAS, the Company desires to provide additional inducement for the
Executive to continue to remain in the ongoing employ of the Company; and

         WHEREAS, this agreement is intended to supersede and replace the
Agreement (the "Prior Agreement") between the Company and the Executive
described on Annex A hereto.

         NOW, THEREFORE, the Company and Executive agree as follows:

         1. Certain Defined Terms: In addition to terms defined elsewhere
herein, the following terms have the following meanings when used in this
Agreement with initial capital letters:

            (a) "Base Pay" means the Executive's annual base salary at a rate
not less than the Executive's annual fixed or base compensation as in effect for
Executive immediately prior to the occurrence of a Change in Control or such
higher rate as may be determined from time to time by the Board of Directors of
the Company (the "Board") or a Committee thereof;

            (b) "Cause" means that, prior to any termination pursuant to Section
3(b) hereof, the Executive shall have committed:

                (i) an intentional act of fraud, embezzlement or theft in
            connection with his duties or in the course of his employment with
            the Company or any Subsidiary;
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                (ii) intentional wrongful damage to property of the Company or
            any Subsidiary;

                (iii) intentional wrongful disclosure of secret processes or
            confidential information of the Company or any Subsidiary; or

                (iv) intentional wrongful engagement in any Competitive
            Activity;

and any such act shall have been materially harmful to the Company. For purposes
of this Agreement, no act or failure to act on the part of the Executive shall
be deemed "intentional" if it was due primarily to an error in judgment or
negligence, but shall be deemed "intentional" only if done or omitted to be done
by the Executive not in good faith and without reasonable belief that his action
or omission was in the best interest of the Company. Notwithstanding the
foregoing, the Executive shall not be deemed to have been terminated for "Cause"
hereunder unless and until there shall have been delivered to the Executive a
copy of a resolution duly adopted by the affirmative vote of not less than
three-quarters of the Board then in office at a meeting of the Board called and
held for such purpose, after reasonable notice to the Executive and an
opportunity for the Executive, together with his counsel (if the Executive
chooses to have counsel present at such meeting), to be heard before the Board,
finding that, in the good faith opinion of the Board, the Executive had
committed an act constituting "Cause" as herein defined and specifying the
particulars thereof in detail. Nothing herein will limit the right of the
Executive or his beneficiaries to contest the validity or propriety of any such
determination;

            (c) "Change in Control" means the occurrence during the Term of any
of the following events:

                (i) The acquisition by any individual, entity or group (within
            the meaning of Section 13(d)(3) or 14(d)(2) of the Exchange Act) (a
            "Person") of beneficial ownership (within the meaning of Rule 13d-3
            promulgated under the Exchange Act) of 19% or more of the combined
            voting power of the then outstanding Voting Stock of the Company;
            provided, however, that for purposes of this Section 1(c)(i), the
            following acquisitions shall not constitute a Change in Control: (A)
            any issuance of Voting Stock of the Company directly from the
            Company that is approved by the Incumbent Board (as defined in
            Section 1(c)(ii), below), (B) any acquisition by the Company of
            Voting Stock of the Company, (C) any acquisition of Voting Stock of
            the Company by any employee benefit plan (or related trust)
            sponsored or maintained by the Company or any Subsidiary, or (D) any
            acquisition of Voting Stock of the Company by any Person pursuant to
            a Business Combination that complies with clauses (A), (B) and (C)
            of section 1(c)(iii) below; or

                (ii) Individuals who, as of the date hereof, constitute the
            Board (the "Incumbent Board") cease for any reason to constitute at
            least a majority of the Board; provided, however, that any
            individual becoming a Director subsequent to the date hereof whose
            election, or nomination for election by the Company's shareholders,
            was approved by a vote of at least two-thirds of the Directors then
            comprising the Incumbent Board (either by a specific vote or by
            approval of the proxy statement of the Company in which such person
            is named as a nominee for director, without objection to such
            nomination) shall be deemed to have been a member of the Incumbent
            Board, but excluding, for this purpose, any such individual whose
            initial assumption of office occurs as a result of an actual or
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            threatened election contest (within the meaning of Rule 14a-11 of
            the Exchange Act) with respect to the election or removal of
            Directors or other actual or threatened solicitation of proxies or
            consents by or on behalf of a Person other than the Board; or

                (iii) consummation of a reorganization, merger or consolidation,
            a sale or other disposition of all or substantially all of the
            assets of the Company, or other transaction (each, a "Business
            Combination"), unless, in each case, immediately following such
            Business Combination, (A) all or substantially all of the
            individuals and entities who were the beneficial owners of Voting
            Stock of the Company immediately prior to such Business Combination
            beneficially own, directly or indirectly, more than two-thirds of
            the combined voting power of the then outstanding shares of Voting
            Stock of the entity resulting from such business Combination
            (including, without limitation, an entity which as a result of such
            transaction owns the Company or all or substantially all of the
            Company's assets either directly or through one or more
            subsidiaries), (B) no Person (other than the Company, such entity
            resulting form such Business Combination, or any employee benefit
            plan (or related trust) sponsored or maintained by the Company, any
            Subsidiary or such entity resulting form such Business Combination)
            beneficially owns, directly or indirectly, 19% or more of the
            combined voting power of the then outstanding shares of Voting Stock
            of the entity resulting from such Business Combination, and (C) at
            least a majority of the members of the Board of Directors of the
            entity resulting from such Business Combination were members of the
            Incumbent Board at the time of the execution of the initial
            agreement or of the action of the Board providing for such Business
            Combination; or

                (iv) approval by the shareholders of the Company of a complete
            liquidation or dissolution of the Company, except pursuant to a
            Business Combination that complies with clauses (A), (B) and (C) of
            Section 1(c)(iii).

            (d) "Competitive Activity" means the Executive's participation,
without the written consent of an officer of the Company, in the management of
any business enterprise if such enterprise engages in substantial and direct
competition with the Company and such enterprise's sales of any product or
service competitive with any product or service of the Company amounted to 10%
of such enterprise's net sales for its most recently completely fiscal year and
if the Company's net sales of said product or service amounted to 10% of the
Company's net sales for its most recently completed fiscal year. "Competitive
Activity" will not include (i) the mere ownership of securities in any such
enterprise and the exercise of rights appurtenant thereto and (ii) participation
in the management of any such enterprise other than in connection with the
competitive operations of such enterprise;

            (e) "Employee Benefits" means the perquisites, benefits and service
credit for benefits as provided under any and all employee retirement income and
welfare benefit policies, plans, programs or arrangements in which Executive is
entitled to participate, including without limitation any stock option, stock
purchase, stock appreciation, savings, pension, supplemental executive
retirement, or other retirement income or welfare benefit, deferred
compensation, incentive compensation, group or other life, health,
medical/hospital or other insurance (whether funded by actual insurance or
self-insured by the Company), disability, salary continuation, expense
reimbursement and other employee benefit policies, plans, programs or
arrangements that may now exist or any equivalent successor policies, plans,
programs or arrangements that
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may be adopted hereafter by the Company, providing perquisites, benefits and
service credit for benefits at least as great in the aggregate as are payable
thereunder prior to a Change in Control;

            (f) "Exchange Act" means the Securities Exchange Act of 1934, as
amended.

            (g) "Incentive Pay" means an annual amount equal to not less than
the highest aggregate annual bonus, incentive or other payments of cash
compensation, in addition to Base Pay, made or to be made in regard to services
rendered in any calendar year during the three calendar years immediately
preceding the year in which the Change in Control occurred pursuant to any
bonus, incentive, profit-sharing, performance, discretionary pay or similar
agreement, policy, plan, program or arrangement (whether or not funded) of the
Company, or any successor thereto providing benefits at least as great as the
benefits payable thereunder prior to a Change in Control;

            (h) "Severance Period" means the period of time commencing on the
date of an occurrence of a Change in Control and continuing until the earliest
of (i) the expiration of thirty days after the first anniversary of the
occurrence of the Change in Control, (ii) the Executive's death, or (iii) the
Executive's attainment of age 65; provided, however, that commencing on the 30th
day following each anniversary of the Change in Control, the Severance Period
will automatically be extended for an additional year unless, not later than 120
calendar days prior to such date, either the Company or the Executive shall have
given written notice to the other that the Severance Period is not to be so
extended; and

            (i) "Subsidiary" means an entity in which the Company directly or
indirectly beneficially owns 50% or more of the outstanding Voting Stock.

            (j) "Term" means the period commencing as of the date hereof and
expiring as of the later of (i) the close of business on December 31, 2003, or
(ii) the expiration of the Severance Period; provided, however, that (A)
commencing on January 1, 2004 and each January 1 thereafter, the term of this
Agreement will automatically be extended for an additional year unless, not
later than September 30 of the immediately preceding year, the Company or the
Executive shall have given notice that it or the Executive, as the case may be,
does not wish to have the Term extended and (B) if, prior to a Change in
Control, the Executive ceases for any reason to be an employee of the Company or
any Subsidiary, thereupon without further action the Term shall be deemed to
have expired and this Agreement will immediately terminate and be of no further
effect. For purposes of this Section 1(j), the Executive shall not be deemed to
have ceased to be an employee of the Company or any Subsidiary by reason of the
transfer of Executive's employment between the Company and any Subsidiary, or
among any Subsidiaries.

            (k) "Voting Stock" means securities entitled to vote generally in
the election of directors.

         2. Operation of Agreement: This Agreement will be effective and binding
immediately upon its execution, but, anything in this Agreement to the contrary
notwithstanding, this Agreement will not be operative unless and until a Change
in Control occurs, whereupon without further action this Agreement shall become
immediately operative.

         3. Termination Following a Change in Control: (a) In the event of the
occurrence of a Change in Control, the Executive's employment may be terminated
by the Company during
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the Severance Period and the Executive shall not be entitled to the benefits
provided by Section 4 only upon the occurrence of one or more of the following
events:

                (i) The Executive's death;

                (ii) If the Executive becomes permanently disabled within the
            meaning of, and begins actually to receive disability benefits
            pursuant to, the long-term disability plan in effect for, or
            applicable to, Executive immediately prior to the Change in Control;
            or

                (iii) Cause.

If, during the Severance Period, the Executive's employment is terminated by the
Company other than pursuant to Section 3(a)(i), 3(a)(ii) or 3(a)(iii), the
Executive will be entitled to the benefits provided by Section 4 hereof.

            b) In the event of the occurrence of a Change in Control, the
Executive may terminate employment with the Company and any Subsidiary during
the Severance Period with the right to severance compensation as provided in
Section 4 upon the occurrence of one or more of the following events (regardless
of whether any other reason, other than Cause as hereinabove provided, for such
termination exists or has occurred, including without limitation other
employment):

                (i) Failure to elect or reelect or otherwise to maintain the
            Executive in the office or the position, or a substantially
            equivalent office or position, of or with the Company and/or a
            Subsidiary, as the case may be, which the Executive held immediately
            prior to a Change in Control, or the removal of the Executive as a
            Director of the Company (or any successor thereto) if the Executive
            shall have been a Director of the Company immediately prior to the
            Change in Control;

                (ii) (I) A significant adverse change in the nature or scope of
            the authorities, powers, functions, responsibilities or duties
            attached to the position with the Company and any Subsidiary which
            the Executive held immediately prior to the Change in Control; (II)
            a reduction in the aggregate of the Executive's Base Pay and
            Incentive Pay received from the Company and any Subsidiary; or (III)
            the termination or denial of the Executive's rights to Employee
            Benefits or a reduction in the scope or value thereof;

                (iii) A determination by the Executive (which determination will
            be conclusive and binding upon the parties hereto provided it has
            been made in good faith and in all events will be presumed to have
            been made in good faith unless otherwise shown by the Company by
            clear and convincing evidence) that a change in circumstances has
            occurred following a Change in Control, including without limitation
            a change in the scope of the business or other activities for which
            the Executive was responsible immediately prior to the Change in
            Control, which has rendered the Executive substantially unable to
            carry out, has substantially hindered Executive's performance of, or
            has caused Executive to suffer a substantial reduction in, any of
            the authorities, powers, functions, responsibilities or duties
            attached to the position held by the Executive immediately prior to
            the Change in Control, which situation is not remedied within
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            10 calendar days after written notice to the Company from the
            Executive of such determination;

                (iv) The liquidation, dissolution, merger, consolidation or
            reorganization of the Company or transfer of all or substantially
            all of its business and/or assets, unless the successor or
            successors (by liquidation, merger, consolidation, reorganization,
            transfer or otherwise) to which all or substantially all of its
            business and/or assets have been transferred (directly or by
            operation of law) assumed all duties and obligations of the Company
            under this Agreement pursuant to Section 10(a);

                (v) The Company relocates its principal executive offices, or
            requires the Executive to have his principal location of work
            changed, to any location which is in excess of 25 miles from the
            location thereof immediately prior to the Change of' Control, or
            requires the Executive to travel away from his office in the course
            of discharging his responsibilities or duties hereunder at least 20%
            more (in terms of aggregate days in any calendar year or in any
            calendar quarter when annualized for purposes of comparison to any
            prior year) than was required of Executive in any of the three full
            years immediately prior to the Change of Control without, in either
            case, his prior written consent;

                (vi) During the period commencing on the 30th day immediately
            preceding the date on which the Severance Period, including any
            extension thereof, is scheduled to terminate pursuant to Section
            1(h) (other than termination of the Severance Period pursuant to
            Section 1(h)(iii) which shall not entitle Executive to terminate
            employment under this Section 3(b)(vi)) and ending on the last day
            of the Severance Period, for any reason, including without
            limitation other employment; or

                (vii) Without limiting the generality or effect of the
            foregoing, any material breach of this Agreement by the Company or
            any successor thereto.

            (c) A termination by the Company pursuant to Section 3(a) or by the
Executive pursuant to Section 3(b) will not affect any rights which the
Executive may have pursuant to any agreement, policy, plan, program or
arrangement of the Company providing Employee Benefits, which rights shall be
governed by the terms thereof.

         4. Severance Compensation: (a) If, following the occurrence of a Change
in Control, the Company terminates the Executive's employment during the
Severance Period other than pursuant to Section 3(a), or if the Executive
terminates his employment pursuant to Section 3(b), the Company will pay to the
Executive the following amounts within five business days after the date (the
"Termination Date") that the Executive's employment is terminated (the effective
date of which shall be the date of termination, or such other date that may be
specified by the Executive if the termination is pursuant to Section 3(b)) and
continue to provide to the Executive the following benefits:

                (i) A lump sum payment (the "Severance Payment") in an amount
            equal to the multiple set forth under Column I on Annex A hereto
            times the sum of (A) Base Pay (at the highest rate in effect for any
            period prior to the Termination Date), plus (B) Incentive Pay
            (determined in accordance with the standards set forth in Section
            1(g)).
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                (ii) (A) for, the number of months set forth under Column II on
            Annex A hereto (the "Continuation Period") following the Termination
            Date, the Company will arrange to provide the Executive with
            Employee Benefits that are welfare benefits (but not stock option,
            stock purchase, stock appreciation or similar compensatory benefits)
            substantially similar to those which the Executive was receiving or
            entitled to receive immediately prior to the Termination Date, and
            (B) such Continuation Period will be considered service with the
            Company for the purpose of determining service credits and benefits
            due and payable to the Executive under the Company's retirement
            income, supplemental executive retirement and other benefit plans of
            the Company applicable to the Executive, his dependents or his
            beneficiaries immediately prior to the Termination Date. If and to
            the extent that any benefit described in subsections (A) and (B) of
            this Section 4(a)(ii) is not or cannot be paid or provided under any
            policy, plan, program or arrangement of the Company or any
            Subsidiary, as the case may be, then the Company will itself pay or
            provide for the payment to the Executive, his dependents and
            beneficiaries, of such Employee Benefits. Without otherwise limiting
            the purposes or effect of Section 5, Employee Benefits otherwise
            receivable by the Executive pursuant to the subsection (A) of this
            Section 4(a)(ii) will be reduced to the extent comparable welfare
            benefits are actually received by the Executive from another
            employer during the Continuation Period following the Executive's
            Termination Date.

            (b) Upon the occurrence of a Change in Control, and without regard
to the termination of the employment of the Executive, all outstanding and
unexercised options theretofore granted by the Company shall, notwithstanding
anything to the contrary set forth in the plan or agreement relating to such
options, become immediately exercisable in full.

            (c) Upon the occurrence of a Change in Control, and without regard
to the termination of the employment of the Executive, any and all restrictions
on all outstanding restricted stock theretofore granted by the Company shall,
notwithstanding anything to the contrary set forth in the plan or agreement
relating to such restricted stock, expire immediately.

            (d) There will be no right of set-off or counterclaim in respect of
any claim, debt or obligation against any payment to or benefit for the
Executive provided for in this Agreement, except as expressly provided in the
last sentence of Section 4(a)(ii).

            (e) Without limiting the rights of the Executive at law or in
equity, if the Company fails to make any payment or provide any benefit required
to be made or provided hereunder on a timely basis, the Company will pay
interest on the amount or value thereof at an annualized rate of interest equal
to the so-called composite "prime rate" as quoted from time to time during the
relevant period in the Northeast Edition of The Wall Street Journal. Such
interest will be payable as it accrues on demand. Any change in such prime rate
will be effective on and as of the date of such change.

            (f) Notwithstanding any other provision hereof, the parties'
respective rights and obligations under this Section 4 and under Section 7 will
survive any termination or expiration of this Agreement following a Change in
Control or the termination of the Executive's employment following a Change in
Control for any reason whatsoever.

         5. No Mitigation Obligation: The Company hereby acknowledges that it
will be difficult and may be impossible (a) for the Executive to find reasonably
comparable employment
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following the Termination Date, and (b) to measure the amount of damages which
Executive may suffer as a result of termination of employment hereunder.
Accordingly, the payment of the severance compensation by the Company to the
Executive in accordance with the terms of this Agreement is hereby acknowledged
by the Company to be reasonable and will be liquidated damages, and the
Executive will not be required to mitigate the amount of any payment provided
for in this Agreement by seeking other employment or otherwise, nor will any
profits, income, earnings or other benefits from any source whatsoever create
any mitigation, offset, reduction or any other obligation on the part of the
Executive hereunder or otherwise, except as expressly provided in the last
sentence of Section 4(a)(ii).

         6. Certain Additional Payments by the Company: (a) Anything in this
Agreement to the contrary notwithstanding, in the event that this Agreement
shall become operative and it shall be determined (as hereafter provided) that
any payment or distribution by the Company or any of its affiliates to or for
the benefit of the Executive, whether paid or payable or distributed or
distributable pursuant to the terms of this Agreement or otherwise pursuant to
or by reason of any other agreement, policy, plan, program or arrangement,
including without limitation any stock option, stock appreciation right or
similar right, or the lapse or termination of any restriction on or the vesting
or exercisability of any of the foregoing (a "Payment"), would be subject to the
excise tax imposed by Section 4999 of the Internal Revenue Code of 1986, as
amended (the "Code") (or any successor provision thereto) by reason of being
considered "contingent on a change in ownership or control" of the Company,
within the meaning of Section 280G of the Code (or any successor provision
thereto) or to any similar tax imposed by state or local law, or any interest or
penalties with respect to such tax (such tax or taxes, together with any such
interest and penalties, being hereafter collectively referred to as the "Excise
Tax"), then the Executive shall be entitled to receive an additional payment or
payments (collectively, a "Gross-Up Payment"); provided, however, that no
Gross-up Payment shall be made with respect to the Excise Tax, if any,
attributable to (A) any incentive stock option, as defined in Section 422A of
the Code ("ISO") granted prior to the execution of this Agreement, or (B) any
stock appreciation or similar right, whether or not limited, granted in tandem
with any ISO described in clause (A). The Gross-Up Payment shall be in an amount
such that, after payment by the Executive of all taxes (including any interest
or penalties imposed with respect to such taxes), including any Excise Tax
imposed upon the Gross-Up Payment, the Executive retains an amount of the
Gross-Up Payment equal to the Excise Tax imposed upon the Payment.

            (b) Subject to the provisions of Section 6(f) hereof, all
determinations required to be made under this Section 6, including whether an
Excise Tax is payable by the Executive and the amount of such Excise Tax and
whether a Gross-Up Payment is required to be paid by the Company to the
Executive and the amount of such Gross-Up Payment, if any, shall be made by a
nationally recognized accounting firm (the "Accounting Firm") selected by the
Executive in his sole discretion. The Executive shall direct the Accounting Firm
to submit its determination and detailed supporting calculations to both the
Company and the Executive within 30 calendar days after the Termination Date, if
applicable, and any such other time or times as may be requested by the Company
or the Executive. If the Accounting Firm determines that any Excise Tax is
payable by the Executive, the Company shall pay the required Gross-Up Payment to
the Executive within five business days after receipt of such determination and
calculations with respect to any Payment to the Executive. If the Accounting
Firm determines that no Excise Tax is payable by the Executive, it shall, at the
same time as it makes such determination, furnish the Company and the Executive
an opinion that the Executive has substantial authority not to report any Excise
Tax on his federal, state or local income or other tax return. As a result of
the uncertainty in the application of Section 4999 of the Code (or any
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successor provision thereto) and the possibility of similar uncertainty
regarding applicable state or local tax law at the time of any determination by
the Accounting Firm hereunder, it is possible that Gross-Up Payments which will
not have been made by the Company should have been made (an "Underpayment"),
consistent with the calculations required to be made hereunder. In the event
that the Company exhausts or fails to pursue its remedies pursuant to Section
6(f) hereof and the Executive thereafter is required to make a payment of any
Excise Tax, the Executive shall direct the Accounting Firm to determine the
amount of the Underpayment that has occurred and to submit its determination and
detailed supporting calculations to both the Company and the Executive as
promptly as possible. Any such Underpayment shall be promptly paid by the
Company to, or for the benefit of, the Executive within five business days after
receipt of such determination and calculations.

            (c) The Company and the Executive shall each provide the Accounting
Firm access to and copies of any books, records and documents in the possession
of the Company or the Executive, as the case may be, reasonably requested by the
Accounting Firm, and otherwise cooperate with the Accounting Firm in connection
with the preparation and issuance of the determinations and calculations
contemplated by Section 6(b) hereof. Any determination by the Accounting Firm as
to the amount of the Gross-Up Payment shall be binding upon the company and the
Executive.

            (d) The federal, state and local income or other tax returns filed
by the Executive shall be prepared and filed on a consistent basis with the
determination of the Accounting Firm with respect to the Excise Tax payable by
the Executive. The Executive shall make proper payment of the amount of any
Excise Payment, and at the request of the Company, provide to the Company true
and correct copies (with any amendments) of his federal income tax return as
filed with the Internal Revenue Service and corresponding state and local tax
returns, if relevant, as filed with the applicable taxing authority, and such
other documents reasonably requested by the Company, evidencing such payment. If
prior to the filing of the Executive's federal income tax return, or
corresponding state or local tax return, if relevant, the Accounting Firm
determines that the amount of the Gross-Up Payment should be reduced, the
Executive shall within five business days pay to the Company the amount of such
reduction.

            (e) The fees and expenses of the Accounting Firm for its services in
connection with the determinations and calculations contemplated by Section 6(b)
hereof shall be borne by the Company. If such fees and expenses are initially
paid by the Executive, the Company shall reimburse the Executive the full amount
of such fees and expenses within five business days after receipt from the
Executive of a statement therefor and reasonable evidence of his payment
thereof.

            (f) The Executive shall notify the Company in writing of any claim
by the Internal Revenue Service or any other taxing authority that, if
successful, would require the payment by the Company of a Gross-Up Payment. Such
notification shall be given as promptly as practicable but no later than 10
business days after the Executive actually receives notice of such claim and the
Executive shall further apprise the Company of the nature of such claim and the
date on which such claim is requested to be paid (in each case, to the extent
known by the Executive). The Executive shall not pay such claim prior to the
earlier of (i) the expiration of the 30-calendar-day period following the date
on which he gives such notice to the Company and (ii) the date that any payment
of amount with respect to such claim is due. If the Company notifies the
Executive in writing prior to the expiration of such period that it desires to
contest such claim, the Executive shall:
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                (i) provide the Company with any written records or documents in
            his possession relating to such claim reasonably requested by the
            Company;

                (ii) take such action in connection with contesting such claim
            as the Company shall reasonably request in writing from time to
            time, including without limitation accepting legal representation
            with respect to such claim by an attorney competent in respect of
            the subject matter and reasonably selected by the Company;

                (iii) cooperate with the Company in good faith in order
            effectively to contest such claim; and

                (iv) permit the Company to participate in any proceedings
            relating to such claim;

provided, however, that the Company shall bear and pay directly all costs and
expenses (including interest and penalties) incurred in connection with such
contest and shall indemnify and hold harmless the Executive, on an after-tax
basis, for and against any Excise Tax or income tax, including interest and
penalties with respect thereto, imposed as a result of such representation and
payment of costs and expenses. Without limiting the foregoing provisions of this
Section 6(f), the Company shall control all proceedings taken in connection with
the contest of any claim contemplated by this Section 6(f) and, at its sole
option, may pursue or forego any and all administrative appeals, proceedings,
hearings and conferences with the taxing authority in respect of such claim
(provided, however, that the Executive may participate therein at his own cost
and expense) and may, at its option, either direct the Executive to pay the tax
claimed and sue for a refund or contest the claim in any permissible manner, and
the Executive agrees to prosecute such contest to a determination before any
administrative tribunal, in a court of initial jurisdiction and in one or more
appellate courts, as the Company shall determine; provided, however, that if the
Company directs the Executive to pay the tax claimed and sue for a refund, the
Company shall advance the amount of such payment to the Executive on an
interest-free basis and shall indemnify and hold the Executive harmless, on an
after-tax basis, from any Excise Tax or income or other tax, including interest
or penalties with respect thereto, imposed with respect to such advance; and
provided further, however, that any extension of the statute of limitations
relating to payment of taxes for the taxable year of the Executive with respect
to which the contested amount is claimed to be due is limited solely to such
contested amount. Furthermore, the Company's control of any such contested claim
shall be limited to issues with respect to which a Gross-Up Payment would be
payable hereunder and the Executive shall be entitled to settle or contest, as
the case may be, any other issue raised by the Internal Revenue Service or any
other taxing authority.

            (g) If, after the receipt by the Executive of an amount advanced by
the Company pursuant to Section 6(f) hereof, the Executive receives any refund
with respect to such claim, the Executive shall (subject to the Company's
complying with the requirements of Section 6(f) hereof) promptly pay to the
Company the amount of such refund (together with any interest paid or credited
thereon after any taxes applicable thereto). If, after the receipt by the
Executive of an amount advanced by the Company pursuant to Section 6(f) hereof,
a determination is made that the Executive shall not be entitled to any refund
with respect to such claim and the Company does not notify the Executive in
writing of its intent to contest such denial or refund prior to the expiration
of 30 calendar days after such determination, then such advance shall be
forgiven and shall not be required to be repaid and the amount of any such
<PAGE>   11
                                      -11-

advance shall offset, to the extent thereof, the amount of Gross-Up Payment
required to be paid by the Company to the Executive pursuant to this Section 6.

         7.  Legal Fees and Expenses; Security. (a) It is the intent of the
Company that the Executive not be required to incur legal fees and the related
expenses associated with the interpretation, enforcement or defense of
Executive's rights under this Agreement by litigation or otherwise because the
cost and expense thereof would substantially detract from the benefits intended
to be extended to the Executive hereunder. Accordingly, if it should appear to
the Executive that the Company has failed to comply with any of its obligations
under this Agreement or in the event that the Company or any other person takes
or threatens to take any action to declare this Agreement void or unenforceable,
or institutes any litigation or other action or proceeding designed to deny, or
to recover from, the Executive the benefits provided or intended to be provided
to the Executive hereunder, the Company irrevocably authorizes the Executive
from time to time to retain counsel of Executive's choice, at the expense of the
Company as hereafter provided, to advise and represent the Executive in
connection with any such interpretation, enforcement or defense, including
without limitation the initiation or defense of any litigation or other legal
action, whether by or against the Company or any Director, officer, stockholder
or other person affiliated with the Company, in any jurisdiction.
Notwithstanding any existing or prior attorney-client relationship between the
Company and such counsel, the Company irrevocably consents to the Executive's
entering into an attorney-client relationship with such counsel, and in that
connection the Company and the Executive agree that a confidential relationship
shall exist between the Executive and such counsel. Without respect to whether
the Executive prevails, in whole or in part, in connection with any of the
foregoing, the Company will pay and be solely financially responsible for any
and all, attorneys' and related fees and expenses incurred by the Executive in
connection with any of the foregoing.

             (b) The severance compensation, benefits and other amounts payable
pursuant to this Agreement shall be secured by amounts deposited or to be
deposited in trust pursuant to certain trust agreements to which the Company
shall be a party.

         8.  Employment Rights; Termination Prior to Change in Control: Nothing
expressed or implied in this Agreement will create any right or duty on the part
of the Company or the Executive to have the Executive remain in the employment
of the Company or any Subsidiary prior to or following any Change in Control.
Any termination of employment of the Executive or the removal of the Executive
from the office or position in the Company following the commencement of any
discussion with a third person that ultimately results in a change in control
shall be deemed to be a termination or removal of the Executive after a Change
in Control for purposes of this Agreement.

         9.  Withholding of Taxes: The Company may withhold from any amounts
payable under this Agreement all federal, state, city or other taxes as the
Company is required to withhold pursuant to any law or government regulation or
ruling.

         10. Successors and Binding Agreement: (a) The Company will require any
successor (whether direct or indirect, by purchase, merger, consolidation,
reorganization or otherwise) to all or substantially all of the business or
assets of the Company, by agreement in form and substance satisfactory to the
Executive, expressly to assume and agree to perform this Agreement in the same
manner and to the same extent the Company would be required to perform if no
such succession had taken place. This Agreement will be binding upon and inure
to the benefit of the Company and any successor to the Company, including
without limitation any persons acquiring directly or indirectly all or
substantially all of the business or assets of the
<PAGE>   12
                                      -12-

Company whether by purchase, merger, consolidation, reorganization or otherwise
(and such successor shall thereafter be deemed the "Company" for the purposes of
this Agreement), but will not otherwise be assignable, transferable or delegable
by the Company.

             (b) This Agreement will inure to the benefit of and be enforceable
by the Executive's personal or legal representatives, executors, administrators,
successors, heirs, distributees and legatees.

             (c) This Agreement is personal in nature and neither of the parties
hereto shall, without the consent of the other, assign, transfer or delegate
this Agreement or any rights or obligations hereunder except as expressly
provided in Sections 10(a) and 10(b) hereof. Without limiting the generality or
effect of the foregoing, the Executive's right to receive payments hereunder
will not be assignable, transferable or delegable, whether by pledge, creation
of a security interest, or otherwise, other than by a transfer by Executive's
will or by the laws of descent and distribution and, in the event of any
attempted assignment or transfer contrary to this Section 10(c), the Company
shall have no liability to pay any amount so attempted to be assigned,
transferred or delegated.

         11. Notices: For all purposes of this Agreement, all communications,
including without limitation notices, consents, requests or approvals, required
or permitted to be given hereunder will be in writing and will be deemed to have
been duly given when hand delivered or dispatched by electronic facsimile
transmission (with receipt thereof orally confirmed), or five business days
after having been mailed by United States registered or certified mail, return
receipt requested, postage prepaid, or three business days after having been
sent by a nationally recognized overnight courier service such as Federal
Express, UPS, or Purolator, addressed to the Company (to the attention of the
Secretary of the Company) at its principal executive office and to the Executive
at his principal residence, or to such other address as any party may have
furnished to the other in writing and in accordance herewith, except that
notices of changes of address shall be effective only upon receipt.

         12. Governing Law: The validity, interpretation, construction and
performance of this Agreement will be governed by and construed in accordance
with the substantive laws of the State of Connecticut, without giving effect to
the principles of conflict of laws of such State.

         13. Validity: If any provision of this Agreement or the application of
any provision hereof to any person or circumstances is held invalid,
unenforceable or otherwise illegal, the remainder of this Agreement and the
application of such provision to any other person or circumstances will not be
affected, and the provision so held to be invalid, unenforceable or otherwise
illegal will be reformed to the extent (and only to the extent) necessary to
make it enforceable, valid or legal.

         14. Miscellaneous: No provision of this Agreement may be modified,
waived or discharged unless such waiver, modification or discharge is agreed to
in writing signed by the Executive and the Company. No waiver by either party
hereto at any time of any breach by the other party hereto or compliance with
any condition or provision of this Agreement to be performed by such other party
will be deemed a waiver of similar or dissimilar provisions or conditions at the
same or at any prior or subsequent time. No agreements or representations, oral
or otherwise, expressed or implied with respect to the subject matter hereof
have been made by either party which are not set forth expressly in this
Agreement. References to Sections are to references to Sections of this
Agreement.
<PAGE>   13
                                      -13-

         15. 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 will constitute one and the same agreement.

         16. Prior Agreement: This Agreement supersedes and replaces the Prior
Agreement which shall, without further action, be terminated as of the date
hereof.

IN WITNESS WHEREOF, the parties have caused this Agreement to be duly executed
and delivered as of the date first above written.

                                 DEXTER CORPORATION

                                 By /s/ David G. Gordon
                                    -------------------------------------
                                    David G. Gordon, President

                                 By /s/ K. Grahame Walker
                                    -------------------------------------
                                    K. Grahame Walker

<PAGE>   14
                                      -14-

                                     ANNEX A

<TABLE>
<CAPTION>
                                                                   Months of Welfare
                                Multiple of Annual               Benefit Continuation
        Prior                    Base Salary and               and Additional Retirement
      Agreement              Incentive Pay Severance             Income Service Credit
      ---------              -----------------------           -------------------------
<S>                          <C>                               <C>
December 15, 1989                       2                                 24
</TABLE><PAGE>   1
                                                                    EXHIBIT 10 B

                               SEVERANCE AGREEMENT

         THIS SEVERANCE AGREEMENT (this "Agreement"), dated as of September 20,
1999, by and between the Dexter Corporation, a Connecticut corporation (the
"Company"), and Ronald C. Benham (the "Executive").

                                   WITNESSETH:

         WHEREAS, the Executive is a senior executive or key employee of the
Company and has made and is expected to continue to make major contributions to
the short and long-term profitability, growth and financial strength of the
Company;

         WHEREAS, the Company recognizes that, as is the case for most publicly
held companies, the possibility of a Change in Control exists;

         WHEREAS, the Company desires to assure itself of both present and
future continuity of management and desires to establish certain minimum
severance benefits for certain of its senior executive officers and other key
employees, including the Executive, applicable in the event of a Change in
Control;

         WHEREAS, the Company wishes to ensure that its senior executives and
other key employees are not practically disabled from discharging their duties
in respect of a proposed or actual transaction involving a Change in Control;

         WHEREAS, the Company desires to provide additional inducement for the
Executive to continue to remain in the ongoing employ of the Company; and

         WHEREAS, this agreement is intended to supersede and replace the
Agreement (the "Prior Agreement") between the Company and the Executive
described on Annex A hereto.

         NOW, THEREFORE, the Company and Executive agree as follows:

         1. Certain Defined Terms: In addition to terms defined elsewhere
herein, the following terms have the following meanings when used in this
Agreement with initial capital letters:

                  (a) "Base Pay" means the Executive's annual base salary at a
rate not less than the Executive's annual fixed or base compensation as in
effect for Executive immediately prior to the occurrence of a Change in Control
or such higher rate as may be determined from time to time by the Board of
Directors of the Company (the "Board") or a Committee thereof;

                  (b) "Cause" means that, prior to any termination pursuant to
Section 3(b) hereof, the Executive shall have committed:

                           (i) an intentional act of fraud, embezzlement or
                  theft in connection with his duties or in the course of his
                  employment with the Company or any Subsidiary;

<PAGE>   2
                                      -2-

                           (ii) intentional wrongful damage to property of the
                  Company or any Subsidiary;

                           (iii) intentional wrongful disclosure of secret
                  processes or confidential information of the Company or any
                  Subsidiary; or

                           (iv) intentional wrongful engagement in any
                  Competitive Activity;

and any such act shall have been materially harmful to the Company. For purposes
of this Agreement, no act or failure to act on the part of the Executive shall
be deemed "intentional" if it was due primarily to an error in judgment or
negligence, but shall be deemed "intentional" only if done or omitted to be done
by the Executive not in good faith and without reasonable belief that his action
or omission was in the best interest of the Company. Notwithstanding the
foregoing, the Executive shall not be deemed to have been terminated for "Cause"
hereunder unless and until there shall have been delivered to the Executive a
copy of a resolution duly adopted by the affirmative vote of not less than
three-quarters of the Board then in office at a meeting of the Board called and
held for such purpose, after reasonable notice to the Executive and an
opportunity for the Executive, together with his counsel (if the Executive
chooses to have counsel present at such meeting), to be heard before the Board,
finding that, in the good faith opinion of the Board, the Executive had
committed an act constituting "Cause" as herein defined and specifying the
particulars thereof in detail. Nothing herein will limit the right of the
Executive or his beneficiaries to contest the validity or propriety of any such
determination;

         (c) "Change in Control" means the occurrence during the Term of any of
the following events:

                           (i) The acquisition by any individual, entity or
                  group (within the meaning of Section 13(d)(3) or 14(d)(2) of
                  the Exchange Act) (a "Person") of beneficial ownership (within
                  the meaning of Rule 13d-3 promulgated under the Exchange Act)
                  of 19% or more of the combined voting power of the then
                  outstanding Voting Stock of the Company; provided, however,
                  that for purposes of this Section 1(c)(i), the following
                  acquisitions shall not constitute a Change in Control: (A) any
                  issuance of Voting Stock of the Company directly from the
                  Company that is approved by the Incumbent Board (as defined in
                  Section 1(c)(ii), below), (B) any acquisition by the Company
                  of Voting Stock of the Company, (C) any acquisition of Voting
                  Stock of the Company by any employee benefit plan (or related
                  trust) sponsored or maintained by the Company or any
                  Subsidiary, or (D) any acquisition of Voting Stock of the
                  Company by any Person pursuant to a Business Combination that
                  complies with clauses (A), (B) and (C) of section 1(c)(iii)
                  below; or

                           (ii) Individuals who, as of the date hereof,
                  constitute the Board (the "Incumbent Board") cease for any
                  reason to constitute at least a majority of the Board;
                  provided, however, that any individual becoming a Director
                  subsequent to the date hereof whose election, or nomination
                  for election by the Company's shareholders, was approved by a
                  vote of at least two-thirds of the Directors then comprising
                  the Incumbent Board (either by a specific vote or by approval
                  of the proxy statement of the Company in which such person is
                  named as a nominee for director, without objection to such
                  nomination) shall be deemed to have been a member of the
                  Incumbent Board, but excluding, for this purpose, any such
                  individual whose initial assumption of office occurs as a
                  result of an actual or
<PAGE>   3
                                      -3-

                  threatened election contest (within the meaning of Rule 14a-11
                  of the Exchange Act) with respect to the election or removal
                  of Directors or other actual or threatened solicitation of
                  proxies or consents by or on behalf of a Person other than the
                  Board; or

                           (iii) consummation of a reorganization, merger or
                  consolidation, a sale or other disposition of all or
                  substantially all of the assets of the Company, or other
                  transaction (each, a "Business Combination"), unless, in each
                  case, immediately following such Business Combination, (A) all
                  or substantially all of the individuals and entities who were
                  the beneficial owners of Voting Stock of the Company
                  immediately prior to such Business Combination beneficially
                  own, directly or indirectly, more than two-thirds of the
                  combined voting power of the then outstanding shares of Voting
                  Stock of the entity resulting from such business Combination
                  (including, without limitation, an entity which as a result of
                  such transaction owns the Company or all or substantially all
                  of the Company's assets either directly or through one or more
                  subsidiaries), (B) no Person (other than the Company, such
                  entity resulting form such Business Combination, or any
                  employee benefit plan (or related trust) sponsored or
                  maintained by the Company, any Subsidiary or such entity
                  resulting form such Business Combination) beneficially owns,
                  directly or indirectly, 19% or more of the combined voting
                  power of the then outstanding shares of Voting Stock of the
                  entity resulting from such Business Combination, and (C) at
                  least a majority of the members of the Board of Directors of
                  the entity resulting from such Business Combination were
                  members of the Incumbent Board at the time of the execution of
                  the initial agreement or of the action of the Board providing
                  for such Business Combination; or

                           (iv) approval by the shareholders of the Company of a
                  complete liquidation or dissolution of the Company, except
                  pursuant to a Business Combination that complies with clauses
                  (A), (B) and (C) of Section 1(c)(iii).

                   (d) "Competitive Activity" means the Executive's
participation, without the written consent of an officer of the Company, in the
management of any business enterprise if such enterprise engages in substantial
and direct competition with the Company and such enterprise's sales of any
product or service competitive with any product or service of the Company
amounted to 10% of such enterprise's net sales for its most recently completely
fiscal year and if the Company's net sales of said product or service amounted
to 10% of the Company's net sales for its most recently completed fiscal year.
"Competitive Activity" will not include (i) the mere ownership of securities in
any such enterprise and the exercise of rights appurtenant thereto and (ii)
participation in the management of any such enterprise other than in connection
with the competitive operations of such enterprise;

                  (e) "Employee Benefits" means the perquisites, benefits and
service credit for benefits as provided under any and all employee retirement
income and welfare benefit policies, plans, programs or arrangements in which
Executive is entitled to participate, including without limitation any stock
option, stock purchase, stock appreciation, savings, pension, supplemental
executive retirement, or other retirement income or welfare benefit, deferred
compensation, incentive compensation, group or other life, health,
medical/hospital or other insurance (whether funded by actual insurance or
self-insured by the Company), disability, salary continuation, expense
reimbursement and other employee benefit policies, plans, programs or
arrangements that may now exist or any equivalent successor policies, plans,
programs or arrangements that
<PAGE>   4
                                      -4-

may be adopted hereafter by the Company, providing perquisites, benefits and
service credit for benefits at least as great in the aggregate as are payable
thereunder prior to a Change in Control;

                  (f) "Exchange Act" means the Securities Exchange Act of 1934,
as amended.

                  (g) "Incentive Pay" means an annual amount equal to not less
than the highest aggregate annual bonus, incentive or other payments of cash
compensation, in addition to Base Pay, made or to be made in regard to services
rendered in any calendar year during the three calendar years immediately
preceding the year in which the Change in Control occurred pursuant to any
bonus, incentive, profit-sharing, performance, discretionary pay or similar
agreement, policy, plan, program or arrangement (whether or not funded) of the
Company, or any successor thereto providing benefits at least as great as the
benefits payable thereunder prior to a Change in Control;

                  (h) "Severance Period" means the period of time commencing on
the date of an occurrence of a Change in Control and continuing until the
earliest of (i) the expiration of thirty days after the first anniversary of the
occurrence of the Change in Control, (ii) the Executive's death, or (iii) the
Executive's attainment of age 65; provided, however, that commencing on the 30th
day following each anniversary of the Change in Control, the Severance Period
will automatically be extended for an additional year unless, not later than 120
calendar days prior to such date, either the Company or the Executive shall have
given written notice to the other that the Severance Period is not to be so
extended; and

                  (i) "Subsidiary" means an entity in which the Company directly
or indirectly beneficially owns 50% or more of the outstanding Voting Stock.

                  (j) "Term" means the period commencing as of the date hereof
and expiring as of the later of (i) the close of business on December 31, 2003,
or (ii) the expiration of the Severance Period; provided, however, that (A)
commencing on January 1, 2004 and each January 1 thereafter, the term of this
Agreement will automatically be extended for an additional year unless, not
later than September 30 of the immediately preceding year, the Company or the
Executive shall have given notice that it or the Executive, as the case may be,
does not wish to have the Term extended and (B) if, prior to a Change in
Control, the Executive ceases for any reason to be an employee of the Company or
any Subsidiary, thereupon without further action the Term shall be deemed to
have expired and this Agreement will immediately terminate and be of no further
effect. For purposes of this Section 1(j), the Executive shall not be deemed to
have ceased to be an employee of the Company or any Subsidiary by reason of the
transfer of Executive's employment between the Company and any Subsidiary, or
among any Subsidiaries.

                  (k) "Voting Stock" means securities entitled to vote generally
in the election of directors.

         2. Operation of Agreement: This Agreement will be effective and binding
immediately upon its execution, but, anything in this Agreement to the contrary
notwithstanding, this Agreement will not be operative unless and until a Change
in Control occurs, whereupon without further action this Agreement shall become
immediately operative.

         3. Termination Following a Change in Control: (a) In the event of the
occurrence of a Change in Control, the Executive's employment may be terminated
by the Company during
<PAGE>   5
                                      -5-

the Severance Period and the Executive shall not be entitled to the benefits
provided by Section 4 only upon the occurrence of one or more of the following
events:

                             (i)    The Executive's death;

                            (ii) If the Executive becomes permanently disabled
                  within the meaning of, and begins actually to receive
                  disability benefits pursuant to, the long-term disability plan
                  in effect for, or applicable to, Executive immediately prior
                  to the Change in Control; or

                           (iii) Cause.

If, during the Severance Period, the Executive's employment is terminated by the
Company other than pursuant to Section 3(a)(i), 3(a)(ii) or 3(a)(iii), the
Executive will be entitled to the benefits provided by Section 4 hereof.

                  b) In the event of the occurrence of a Change in Control, the
Executive may terminate employment with the Company and any Subsidiary during
the Severance Period with the right to severance compensation as provided in
Section 4 upon the occurrence of one or more of the following events (regardless
of whether any other reason, other than Cause as hereinabove provided, for such
termination exists or has occurred, including without limitation other
employment):

                           (i) Failure to elect or reelect or otherwise to
                  maintain the Executive in the office or the position, or a
                  substantially equivalent office or position, of or with the
                  Company and/or a Subsidiary, as the case may be, which the
                  Executive held immediately prior to a Change in Control, or
                  the removal of the Executive as a Director of the Company (or
                  any successor thereto) if the Executive shall have been a
                  Director of the Company immediately prior to the Change in
                  Control;

                           (ii) (I) A significant adverse change in the nature
                  or scope of the authorities, powers, functions,
                  responsibilities or duties attached to the position with the
                  Company and any Subsidiary which the Executive held
                  immediately prior to the Change in Control; (II) a reduction
                  in the aggregate of the Executive's Base Pay and Incentive Pay
                  received from the Company and any Subsidiary; or (III) the
                  termination or denial of the Executive's rights to Employee
                  Benefits or a reduction in the scope or value thereof;

                           (iii) A determination by the Executive (which
                  determination will be conclusive and binding upon the parties
                  hereto provided it has been made in good faith and in all
                  events will be presumed to have been made in good faith unless
                  otherwise shown by the Company by clear and convincing
                  evidence) that a change in circumstances has occurred
                  following a Change in Control, including without limitation a
                  change in the scope of the business or other activities for
                  which the Executive was responsible immediately prior to the
                  Change in Control, which has rendered the Executive
                  substantially unable to carry out, has substantially hindered
                  Executive's performance of, or has caused Executive to suffer
                  a substantial reduction in, any of the authorities, powers,
                  functions, responsibilities or duties attached to the position
                  held by the Executive immediately prior to the Change in
                  Control, which situation is not remedied within
<PAGE>   6
                                      -6-

                  10 calendar days after written notice to the Company from the
                  Executive of such determination;

                           (iv) The liquidation, dissolution, merger,
                  consolidation or reorganization of the Company or transfer of
                  all or substantially all of its business and/or assets, unless
                  the successor or successors (by liquidation, merger,
                  consolidation, reorganization, transfer or otherwise) to which
                  all or substantially all of its business and/or assets have
                  been transferred (directly or by operation of law) assumed all
                  duties and obligations of the Company under this Agreement
                  pursuant to Section 10(a);

                           (v) The Company relocates its principal executive
                  offices, or requires the Executive to have his principal
                  location of work changed, to any location which is in excess
                  of 25 miles from the location thereof immediately prior to the
                  Change of' Control, or requires the Executive to travel away
                  from his office in the course of discharging his
                  responsibilities or duties hereunder at least 20% more (in
                  terms of aggregate days in any calendar year or in any
                  calendar quarter when annualized for purposes of comparison to
                  any prior year) than was required of Executive in any of the
                  three full years immediately prior to the Change of Control
                  without, in either case, his prior written consent;

                           (vi) During the period commencing on the 30th day
                  immediately preceding the date on which the Severance Period,
                  including any extension thereof, is scheduled to terminate
                  pursuant to Section 1(h) (other than termination of the
                  Severance Period pursuant to Section 1(h)(iii) which shall not
                  entitle Executive to terminate employment under this Section
                  3(b)(vi)) and ending on the last day of the Severance Period,
                  for any reason, including without limitation other employment;
                  or

                           (vii) Without limiting the generality or effect of
                  the foregoing, any material breach of this Agreement by the
                  Company or any successor thereto.

                  (c) A termination by the Company pursuant to Section 3(a) or
by the Executive pursuant to Section 3(b) will not affect any rights which the
Executive may have pursuant to any agreement, policy, plan, program or
arrangement of the Company providing Employee Benefits, which rights shall be
governed by the terms thereof.

         4. Severance Compensation: (a) If, following the occurrence of a Change
in Control, the Company terminates the Executive's employment during the
Severance Period other than pursuant to Section 3(a), or if the Executive
terminates his employment pursuant to Section 3(b), the Company will pay to the
Executive the following amounts within five business days after the date (the
"Termination Date") that the Executive's employment is terminated (the effective
date of which shall be the date of termination, or such other date that may be
specified by the Executive if the termination is pursuant to Section 3(b)) and
continue to provide to the Executive the following benefits:

                           (i) A lump sum payment (the "Severance Payment") in
                  an amount equal to the multiple set forth under Column I on
                  Annex A hereto times the sum of (A) Base Pay (at the highest
                  rate in effect for any period prior to the Termination Date),
                  plus (B) Incentive Pay (determined in accordance with the
                  standards set forth in Section 1(g)).
<PAGE>   7
                                      -7-

                           (ii) (A) for, the number of months set forth under
                  Column II on Annex A hereto (the "Continuation Period")
                  following the Termination Date, the Company will arrange to
                  provide the Executive with Employee Benefits that are welfare
                  benefits (but not stock option, stock purchase, stock
                  appreciation or similar compensatory benefits) substantially
                  similar to those which the Executive was receiving or entitled
                  to receive immediately prior to the Termination Date, and (B)
                  such Continuation Period will be considered service with the
                  Company for the purpose of determining service credits and
                  benefits due and payable to the Executive under the Company's
                  retirement income, supplemental executive retirement and other
                  benefit plans of the Company applicable to the Executive, his
                  dependents or his beneficiaries immediately prior to the
                  Termination Date. If and to the extent that any benefit
                  described in subsections (A) and (B) of this Section 4(a)(ii)
                  is not or cannot be paid or provided under any policy, plan,
                  program or arrangement of the Company or any Subsidiary, as
                  the case may be, then the Company will itself pay or provide
                  for the payment to the Executive, his dependents and
                  beneficiaries, of such Employee Benefits. Without otherwise
                  limiting the purposes or effect of Section 5, Employee
                  Benefits otherwise receivable by the Executive pursuant to the
                  subsection (A) of this Section 4(a)(ii) will be reduced to the
                  extent comparable welfare benefits are actually received by
                  the Executive from another employer during the Continuation
                  Period following the Executive's Termination Date.

                  (b) Upon the occurrence of a Change in Control, and without
regard to the termination of the employment of the Executive, all outstanding
and unexercised options theretofore granted by the Company shall,
notwithstanding anything to the contrary set forth in the plan or agreement
relating to such options, become immediately exercisable in full.

                  (c) Upon the occurrence of a Change in Control, and without
regard to the termination of the employment of the Executive, any and all
restrictions on all outstanding restricted stock theretofore granted by the
Company shall, notwithstanding anything to the contrary set forth in the plan or
agreement relating to such restricted stock, expire immediately.

                  (d) There will be no right of set-off or counterclaim in
respect of any claim, debt or obligation against any payment to or benefit for
the Executive provided for in this Agreement, except as expressly provided in
the last sentence of Section 4(a)(ii).

                  (e) Without limiting the rights of the Executive at law or in
equity, if the Company fails to make any payment or provide any benefit required
to be made or provided hereunder on a timely basis, the Company will pay
interest on the amount or value thereof at an annualized rate of interest equal
to the so-called composite "prime rate" as quoted from time to time during the
relevant period in the Northeast Edition of The Wall Street Journal. Such
interest will be payable as it accrues on demand. Any change in such prime rate
will be effective on and as of the date of such change.

                  (f) Notwithstanding any other provision hereof, the parties'
respective rights and obligations under this Section 4 and under Section 7 will
survive any termination or expiration of this Agreement following a Change in
Control or the termination of the Executive's employment following a Change in
Control for any reason whatsoever.

         5. No Mitigation Obligation: The Company hereby acknowledges that it
will be difficult and may be impossible (a) for the Executive to find reasonably
comparable employment
<PAGE>   8
                                      -8-

following the Termination Date, and (b) to measure the amount of damages which
Executive may suffer as a result of termination of employment hereunder.
Accordingly, the payment of the severance compensation by the Company to the
Executive in accordance with the terms of this Agreement is hereby acknowledged
by the Company to be reasonable and will be liquidated damages, and the
Executive will not be required to mitigate the amount of any payment provided
for in this Agreement by seeking other employment or otherwise, nor will any
profits, income, earnings or other benefits from any source whatsoever create
any mitigation, offset, reduction or any other obligation on the part of the
Executive hereunder or otherwise, except as expressly provided in the last
sentence of Section 4(a)(ii).

         6.       Certain Additional Payments by the Company:
(a) Anything in this Agreement to the contrary notwithstanding, in the event
that this Agreement shall become operative and it shall be determined (as
hereafter provided) that any payment or distribution by the Company or any of
its affiliates to or for the benefit of the Executive, whether paid or payable
or distributed or distributable pursuant to the terms of this Agreement or
otherwise pursuant to or by reason of any other agreement, policy, plan, program
or arrangement, including without limitation any stock option, stock
appreciation right or similar right, or the lapse or termination of any
restriction on or the vesting or exercisability of any of the foregoing (a
"Payment"), would be subject to the excise tax imposed by Section 4999 of the
Internal Revenue Code of 1986, as amended (the "Code") (or any successor
provision thereto) by reason of being considered "contingent on a change in
ownership or control" of the Company, within the meaning of Section 280G of the
Code (or any successor provision thereto) or to any similar tax imposed by state
or local law, or any interest or penalties with respect to such tax (such tax or
taxes, together with any such interest and penalties, being hereafter
collectively referred to as the "Excise Tax"), then the Executive shall be
entitled to receive an additional payment or payments (collectively, a "Gross-Up
Payment"); provided, however, that no Gross-up Payment shall be made with
respect to the Excise Tax, if any, attributable to (A) any incentive stock
option, as defined in Section 422A of the Code ("ISO") granted prior to the
execution of this Agreement, or (B) any stock appreciation or similar right,
whether or not limited, granted in tandem with any ISO described in clause (A).
The Gross-Up Payment shall be in an amount such that, after payment by the
Executive of all taxes (including any interest or penalties imposed with respect
to such taxes), including any Excise Tax imposed upon the Gross-Up Payment, the
Executive retains an amount of the Gross-Up Payment equal to the Excise Tax
imposed upon the Payment.

                 (b) Subject to the provisions of Section 6(f) hereof, all
determinations required to be made under this Section 6, including whether an
Excise Tax is payable by the Executive and the amount of such Excise Tax and
whether a Gross-Up Payment is required to be paid by the Company to the
Executive and the amount of such Gross-Up Payment, if any, shall be made by a
nationally recognized accounting firm (the "Accounting Firm") selected by the
Executive in his sole discretion. The Executive shall direct the Accounting Firm
to submit its determination and detailed supporting calculations to both the
Company and the Executive within 30 calendar days after the Termination Date, if
applicable, and any such other time or times as may be requested by the Company
or the Executive. If the Accounting Firm determines that any Excise Tax is
payable by the Executive, the Company shall pay the required Gross-Up Payment to
the Executive within five business days after receipt of such determination and
calculations with respect to any Payment to the Executive. If the Accounting
Firm determines that no Excise Tax is payable by the Executive, it shall, at the
same time as it makes such determination, furnish the Company and the Executive
an opinion that the Executive has substantial authority not to report any Excise
Tax on his federal, state or local income or other tax return. As a result of
the uncertainty in the application of Section 4999 of the Code (or any
<PAGE>   9
                                      -9-

successor provision thereto) and the possibility of similar uncertainty
regarding applicable state or local tax law at the time of any determination by
the Accounting Firm hereunder, it is possible that Gross-Up Payments which will
not have been made by the Company should have been made (an "Underpayment"),
consistent with the calculations required to be made hereunder. In the event
that the Company exhausts or fails to pursue its remedies pursuant to Section
6(f) hereof and the Executive thereafter is required to make a payment of any
Excise Tax, the Executive shall direct the Accounting Firm to determine the
amount of the Underpayment that has occurred and to submit its determination and
detailed supporting calculations to both the Company and the Executive as
promptly as possible. Any such Underpayment shall be promptly paid by the
Company to, or for the benefit of, the Executive within five business days after
receipt of such determination and calculations.

                 (c) The Company and the Executive shall each provide the
Accounting Firm access to and copies of any books, records and documents in the
possession of the Company or the Executive, as the case may be, reasonably
requested by the Accounting Firm, and otherwise cooperate with the Accounting
Firm in connection with the preparation and issuance of the determinations and
calculations contemplated by Section 6(b) hereof. Any determination by the
Accounting Firm as to the amount of the Gross-Up Payment shall be binding upon
the company and the Executive.

                 (d) The federal, state and local income or other tax returns
filed by the Executive shall be prepared and filed on a consistent basis with
the determination of the Accounting Firm with respect to the Excise Tax payable
by the Executive. The Executive shall make proper payment of the amount of any
Excise Payment, and at the request of the Company, provide to the Company true
and correct copies (with any amendments) of his federal income tax return as
filed with the Internal Revenue Service and corresponding state and local tax
returns, if relevant, as filed with the applicable taxing authority, and such
other documents reasonably requested by the Company, evidencing such payment. If
prior to the filing of the Executive's federal income tax return, or
corresponding state or local tax return, if relevant, the Accounting Firm
determines that the amount of the Gross-Up Payment should be reduced, the
Executive shall within five business days pay to the Company the amount of such
reduction.

                 (e) The fees and expenses of the Accounting Firm for its
services in connection with the determinations and calculations contemplated by
Section 6(b) hereof shall be borne by the Company. If such fees and expenses are
initially paid by the Executive, the Company shall reimburse the Executive the
full amount of such fees and expenses within five business days after receipt
from the Executive of a statement therefor and reasonable evidence of his
payment thereof.

                 (f) The Executive shall notify the Company in writing of any
claim by the Internal Revenue Service or any other taxing authority that, if
successful, would require the payment by the Company of a Gross-Up Payment. Such
notification shall be given as promptly as practicable but no later than 10
business days after the Executive actually receives notice of such claim and the
Executive shall further apprise the Company of the nature of such claim and the
date on which such claim is requested to be paid (in each case, to the extent
known by the Executive). The Executive shall not pay such claim prior to the
earlier of (i) the expiration of the 30-calendar-day period following the date
on which he gives such notice to the Company and (ii) the date that any payment
of amount with respect to such claim is due. If the Company notifies the
Executive in writing prior to the expiration of such period that it desires to
contest such claim, the Executive shall:
<PAGE>   10
                                      -10-

                           (i) provide the Company with any written records or
                  documents in his possession relating to such claim reasonably
                  requested by the Company;

                           (ii) take such action in connection with contesting
                  such claim as the Company shall reasonably request in writing
                  from time to time, including without limitation accepting
                  legal representation with respect to such claim by an attorney
                  competent in respect of the subject matter and reasonably
                  selected by the Company;

                           (iii) cooperate with the Company in good faith in
                  order effectively to contest such claim; and

                           (iv) permit the Company to participate in any
                  proceedings relating to such claim;

provided, however, that the Company shall bear and pay directly all costs and
expenses (including interest and penalties) incurred in connection with such
contest and shall indemnify and hold harmless the Executive, on an after-tax
basis, for and against any Excise Tax or income tax, including interest and
penalties with respect thereto, imposed as a result of such representation and
payment of costs and expenses. Without limiting the foregoing provisions of this
Section 6(f), the Company shall control all proceedings taken in connection with
the contest of any claim contemplated by this Section 6(f) and, at its sole
option, may pursue or forego any and all administrative appeals, proceedings,
hearings and conferences with the taxing authority in respect of such claim
(provided, however, that the Executive may participate therein at his own cost
and expense) and may, at its option, either direct the Executive to pay the tax
claimed and sue for a refund or contest the claim in any permissible manner, and
the Executive agrees to prosecute such contest to a determination before any
administrative tribunal, in a court of initial jurisdiction and in one or more
appellate courts, as the Company shall determine; provided, however, that if the
Company directs the Executive to pay the tax claimed and sue for a refund, the
Company shall advance the amount of such payment to the Executive on an
interest-free basis and shall indemnify and hold the Executive harmless, on an
after-tax basis, from any Excise Tax or income or other tax, including interest
or penalties with respect thereto, imposed with respect to such advance; and
provided further, however, that any extension of the statute of limitations
relating to payment of taxes for the taxable year of the Executive with respect
to which the contested amount is claimed to be due is limited solely to such
contested amount. Furthermore, the Company's control of any such contested claim
shall be limited to issues with respect to which a Gross-Up Payment would be
payable hereunder and the Executive shall be entitled to settle or contest, as
the case may be, any other issue raised by the Internal Revenue Service or any
other taxing authority.

                  (g) If, after the receipt by the Executive of an amount
advanced by the Company pursuant to Section 6(f) hereof, the Executive receives
any refund with respect to such claim, the Executive shall (subject to the
Company's complying with the requirements of Section 6(f) hereof) promptly pay
to the Company the amount of such refund (together with any interest paid or
credited thereon after any taxes applicable thereto). If, after the receipt by
the Executive of an amount advanced by the Company pursuant to Section 6(f)
hereof, a determination is made that the Executive shall not be entitled to any
refund with respect to such claim and the Company does not notify the Executive
in writing of its intent to contest such denial or refund prior to the
expiration of 30 calendar days after such determination, then such advance shall
be forgiven and shall not be required to be repaid and the amount of any such
<PAGE>   11
                                      -11-

advance shall offset, to the extent thereof, the amount of Gross-Up Payment
required to be paid by the Company to the Executive pursuant to this Section 6.

         7. Legal Fees and Expenses; Security. (a) It is the intent of the
Company that the Executive not be required to incur legal fees and the related
expenses associated with the interpretation, enforcement or defense of
Executive's rights under this Agreement by litigation or otherwise because the
cost and expense thereof would substantially detract from the benefits intended
to be extended to the Executive hereunder. Accordingly, if it should appear to
the Executive that the Company has failed to comply with any of its obligations
under this Agreement or in the event that the Company or any other person takes
or threatens to take any action to declare this Agreement void or unenforceable,
or institutes any litigation or other action or proceeding designed to deny, or
to recover from, the Executive the benefits provided or intended to be provided
to the Executive hereunder, the Company irrevocably authorizes the Executive
from time to time to retain counsel of Executive's choice, at the expense of the
Company as hereafter provided, to advise and represent the Executive in
connection with any such interpretation, enforcement or defense, including
without limitation the initiation or defense of any litigation or other legal
action, whether by or against the Company or any Director, officer, stockholder
or other person affiliated with the Company, in any jurisdiction.
Notwithstanding any existing or prior attorney-client relationship between the
Company and such counsel, the Company irrevocably consents to the Executive's
entering into an attorney-client relationship with such counsel, and in that
connection the Company and the Executive agree that a confidential relationship
shall exist between the Executive and such counsel. Without respect to whether
the Executive prevails, in whole or in part, in connection with any of the
foregoing, the Company will pay and be solely financially responsible for any
and all, attorneys' and related fees and expenses incurred by the Executive in
connection with any of the foregoing.

                  (b) The severance compensation, benefits and other amounts
payable pursuant to this Agreement shall be secured by amounts deposited or to
be deposited in trust pursuant to certain trust agreements to which the Company
shall be a party.

         8. Employment Rights; Termination Prior to Change in Control: Nothing
expressed or implied in this Agreement will create any right or duty on the part
of the Company or the Executive to have the Executive remain in the employment
of the Company or any Subsidiary prior to or following any Change in Control.
Any termination of employment of the Executive or the removal of the Executive
from the office or position in the Company following the commencement of any
discussion with a third person that ultimately results in a change in control
shall be deemed to be a termination or removal of the Executive after a Change
in Control for purposes of this Agreement.

         9. Withholding of Taxes: The Company may withhold from any amounts
payable under this Agreement all federal, state, city or other taxes as the
Company is required to withhold pursuant to any law or government regulation or
ruling.

         10. Successors and Binding Agreement: (a) The Company will require any
successor (whether direct or indirect, by purchase, merger, consolidation,
reorganization or otherwise) to all or substantially all of the business or
assets of the Company, by agreement in form and substance satisfactory to the
Executive, expressly to assume and agree to perform this Agreement in the same
manner and to the same extent the Company would be required to perform if no
such succession had taken place. This Agreement will be binding upon and inure
to the benefit of the Company and any successor to the Company, including
without limitation any persons acquiring directly or indirectly all or
substantially all of the business or assets of the
<PAGE>   12
                                      -12-

Company whether by purchase, merger, consolidation, reorganization or otherwise
(and such successor shall thereafter be deemed the "Company" for the purposes of
this Agreement), but will not otherwise be assignable, transferable or delegable
by the Company.

                 (b) This Agreement will inure to the benefit of and be
enforceable by the Executive's personal or legal representatives, executors,
administrators, successors, heirs, distributees and legatees.

                 (c) This Agreement is personal in nature and neither of the
parties hereto shall, without the consent of the other, assign, transfer or
delegate this Agreement or any rights or obligations hereunder except as
expressly provided in Sections 10(a) and 10(b) hereof. Without limiting the
generality or effect of the foregoing, the Executive's right to receive payments
hereunder will not be assignable, transferable or delegable, whether by pledge,
creation of a security interest, or otherwise, other than by a transfer by
Executive's will or by the laws of descent and distribution and, in the event of
any attempted assignment or transfer contrary to this Section 10(c), the Company
shall have no liability to pay any amount so attempted to be assigned,
transferred or delegated.

         11. Notices: For all purposes of this Agreement, all communications,
including without limitation notices, consents, requests or approvals, required
or permitted to be given hereunder will be in writing and will be deemed to have
been duly given when hand delivered or dispatched by electronic facsimile
transmission (with receipt thereof orally confirmed), or five business days
after having been mailed by United States registered or certified mail, return
receipt requested, postage prepaid, or three business days after having been
sent by a nationally recognized overnight courier service such as Federal
Express, UPS, or Purolator, addressed to the Company (to the attention of the
Secretary of the Company) at its principal executive office and to the Executive
at his principal residence, or to such other address as any party may have
furnished to the other in writing and in accordance herewith, except that
notices of changes of address shall be effective only upon receipt.

         12. Governing Law: The validity, interpretation, construction and
performance of this Agreement will be governed by and construed in accordance
with the substantive laws of the State of Connecticut, without giving effect to
the principles of conflict of laws of such State.

         13. Validity: If any provision of this Agreement or the application of
any provision hereof to any person or circumstances is held invalid,
unenforceable or otherwise illegal, the remainder of this Agreement and the
application of such provision to any other person or circumstances will not be
affected, and the provision so held to be invalid, unenforceable or otherwise
illegal will be reformed to the extent (and only to the extent) necessary to
make it enforceable, valid or legal.

         14. Miscellaneous: No provision of this Agreement may be modified,
waived or discharged unless such waiver, modification or discharge is agreed to
in writing signed by the Executive and the Company. No waiver by either party
hereto at any time of any breach by the other party hereto or compliance with
any condition or provision of this Agreement to be performed by such other party
will be deemed a waiver of similar or dissimilar provisions or conditions at the
same or at any prior or subsequent time. No agreements or representations, oral
or otherwise, expressed or implied with respect to the subject matter hereof
have been made by either party which are not set forth expressly in this
Agreement. References to Sections are to references to Sections of this
Agreement.
<PAGE>   13
                                      -13-

         15. 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 will constitute one and the same agreement.

         16. Prior Agreement: This Agreement supersedes and replaces the Prior
Agreement which shall, without further action, be terminated as of the date
hereof.

IN WITNESS WHEREOF, the parties have caused this Agreement to be duly executed
and delivered as of the date first above written.

                                    DEXTER CORPORATION

                                    By   /s/  K. Grahame Walker
                                         K. Grahame Walker, Chairman and Chief
                                         Executive Officer

                                    By   /s/ Ronald C. Benham
                                         Ronald C. Benham
<PAGE>   14
                                      -14-

                                     ANNEX A

<TABLE>
<CAPTION>
                                                                               Months of Welfare
                                  Multiple of Annual                         Benefit Continuation
        Prior                      Base Salary and                       and Additional Retirement
   Agreement                 Incentive Pay Severance                         Income Service Credit
   ---------                 -----------------------                         ---------------------
<S>                         <C>                                         <C>
December 20, 1991                         1                                           12
</TABLE>

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