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                                                                   EXHIBIT 10.10




















                            THERMAL CYCLER SUPPLIER
                            AUTHORIZATION AGREEMENT




















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                            THERMAL CYCLER SUPPLIER
                            AUTHORIZATION AGREEMENT

        This Agreement ("Agreement"), effective January 1, 1995 ("Effective
Date"), is made by and between The Perkin-Elmer Corporation, a New York
corporation having an office at 761 Main Avenue, Norwalk, Connecticut 06859
("Perkin-Elmer"), and Stratagene, a California corporation having an office at
11011 North Torrey Pines Road, La Jolla, California 92037 ("Thermal Cycler
Supplier"), referred to collectively herein as the "Parties".

        Whereas, Perkin-Elmer has the power to convey limited rights for
research and in certain other fields under U.S. Patent Nos. 4,683,195,
4,683,202 and 4,965,188, describing and claiming gene amplification processes,
including a process known as the polymerase chain reaction ("PCR") process,
which are owned by Hoffman-La Roche Inc., and corresponding counterpart patents
and patent applications in other countries, which are owned by F. Hoffmann-La
Roche Ltd (both of which are referred to collectively herein as "Roche").

        Whereas, Perkin-Elmer offers to PCR users commercial and non-commercial
license rights under these patents and patent applications for automated
performance of the PCR process for research and certain other fields that
include, inter alia, an up-front fee component based on the capacity of thermal
cyclers used to perform the process.

        Whereas, Perkin-Elmer offers to suppliers of thermal cyclers certain
license rights under those patents, namely, an authorization to sell and
distribute their instruments with a label conveying to their customers rights
under the up-front fee component of the PCR licenses described above, and the
right to promote their instruments as "Authorized Thermal Cyclers" for PCR.

         Whereas, Perkin-Elmer also has the power to convey limited license
rights under U.S. Patent Nos. 5,038,852 and 5,333,675, describing and claiming
automated apparatus suitable for performing the PCR process, any apparatus
claim issuing from an application claiming priority of U.S. application


                                      -1-
<PAGE>

Serial No. 833,368 or U.S. application Serial No. 899,061 (both filed in 1986)
and apparatus claims in corresponding counterpart patents and patent
applications in other countries ("PCR Instrument Patents").

     WHEREAS, Perkin-Elmer offers the above process rights and apparatus rights
separately or in combination and, Thermal Cycler Supplier has requested PCR
process license rights only, without rights under any apparatus claims.

         NOW, THEREFORE, the Parties agree as follows:

         1.    DEFINITIONS

         1.1 "AMPLIFICATION PATENT RIGHTS" shall mean the nucleic acid
amplification processes, including particularly the PCR process, covered by:
United States Patent Nos. 4,683,195, 4,683,202 and 4,695,188; any amplification
process claim issuing from an application claiming priority of U.S. application
Serial No. 833,368 or U.S. application Serial No. 899,061 (both filed in 1986);
and any corresponding amplification process claim in patents and patent
applications in other countries claiming priority of any of them.

        1.2 "AUTHORIZED REAGENT" shall mean a DNA polymerase whose use in
performance of the PCR process is covered by the running-royalty component of a
PCR process license for internal research and development. The running-royalty
component of that license may be obtained through the purchase of reagents
bearing a valid label conveying the running-royalty component; alternatively, it
may be purchased from Perkin-Elmer. Other PCR process licenses in the Fields
also require use of Authorized Reagents.

        1.3 "AUTHORIZED THERMAL CYCLER" shall mean a thermal cycler or
temperature cycling instrument whose use in automated performance of the PCR
process is covered by the up-front fee component of a PCR process license for
internal research and development. The up-front fee component of that license
may be obtained through the purchase of a thermal cycler or temperature


                                      -2-
<PAGE>

cycling instrument bearing a valid label conveying the up-front component;
alternatively, it may be purchased from Perkin-Elmer. Other PCR process licenses
in the Fields also require use of an instrument whose use is similarly covered,
i.e., an 'Authorized Thermal Cycler".

         1.4 "FIELDS" shall mean research and development, quality assurance or
control, environmental testing, plant diagnostics, identity testing (other than
parentage testing for humans) and forensics.

         1.5   "TERRITORY" shall mean worldwide.

         1.6   "THIRD PARTY" shall mean a party other than the Parties.

         2. GRANT

         2.1 Upon the terms and subject to the exceptions and conditions of this
Agreement, Perkin-Elmer grants to Thermal Cycler Supplier the following
personal, non-transferable, royalty-bearing, non-exclusive rights in the
Territory under the Amplification Patent Rights:

         (a) Thermal Cycler Supplier is hereby authorized to sell and distribute
to end users, directly or through its distributors and under Thermal Cycler
Supplier's name and trademarks, thermal cyclers and temperature cycling
instruments manufactured by Thermal Cycler Supplier or manufactured for Thermal
Cycler Supplier for sale under its name and trademarks, but not otherwise to
sell or distribute to thermal cycler suppliers, with a label conveying to end
users (including Thermal Cycler Supplier itself) in the Fields the up-front
rights of PCR process licenses as specified in the label set forth in Section
5.1 below, that is, with an Authorized Thermal Cycler label; and

         (b) Thermal Cycler Supplier may advertise and promote thermal cyclers
and temperature cycling instruments so labeled as Authorized Thermal Cyclers for
PCR.


                                      -3-
<PAGE>

         2.2 No right, immunity, authorization or license is granted under this
Agreement, expressly or by implication, under any apparatus claim of any patent
or patent application owned by or licensed to Perkin-Elmer or Roche. Neither
this Agreement nor any grant hereunder shall affect the rights of the Parties
with respect to any such claim vis-a-vis any thermal cycler or temperature
cycling instrument, or the enforcement of those rights.

         2.3 No right, immunity, authorization or license is granted under this
Agreement, expressly or by implication, for any other purpose, or in any other
field, including: to make, have made, use or sell any polymerase amplification
reagent or kit; or to perform PCR or nucleic acid amplification that is not
fully licensed under the Amplification Patent Rights. No right, immunity,
authorization or license is granted under this Agreement, expressly or by
implication, under any patent or patent application not expressly included in
Amplification Patent Rights.

         2.4 Rights granted to Thermal Cycler Supplier by this Agreement are
personal to Thermal Cycler Supplier alone. Thermal Cycler Supplier shall have no
right to sublicense, assign or otherwise transfer or share it rights hereunder.
Notwithstanding the foregoing, Thermal Cycler Supplier may exercise its right to
market, sell and distribute under Section 2.1 through independent distributors.

         3. FEES, ROYALTIES, RECORDS AND REPORTS

         3.1 For the authorization rights granted under Article 2, Thermal
Cycler Supplier shall pay to Perkin-Elmer: a license issue fee of $*** plus,
for each thermal cycler or temperature cycling instrument delivered of invoiced
by the Thermal Cycler Supplier after the Effective Date of this Agreement, a
royalty payment as follows,

         (a) for calendar year 1995: $*** for a capacity of up to *** samples
plus $*** for each additional *** samples or part thereof:

        Payment($) = *** + *** x (maximum sample capacity - ***)/***,

         where the calculated fraction, (maximum sample capacity - ***)/***, is
rounded to the next higher whole number; and,


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                                      -4-
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         (b) from January 1, 1996: $*** for a capacity of up to *** samples plus
$*** for each additional *** samples or part thereof;

         Payment($) = *** + *** x (maximum sample capacity - ***)/***,

         where the calculated fraction, (maximum sample capacity - ***)/***, is
rounded to the next higher whole number.

The license issue fee shall be due and owing and shall be paid on execution of
this Agreement. The per-thermal cycler fees shall be paid as specified in
Sections 3.4 and 3.5. Each instrument for which that fee is paid shall be an
Authorized Thermal Cycler and shall be so designated pursuant to Article 5
hereof.

         3.2 All amounts payable hereunder shall be payable in United States
dollars.

         3.3 Thermal Cycler Supplier shall keep full true and accurate books of
account containing all particulars necessary to show the amount payable to
Perkin-Elmer under this Agreement. Such books and the supporting data shall be
open at all reasonable times, for three (3) years following the end of the
calendar year to which they pertain (and access shall not be denied thereafter,
if reasonably available), to the inspection of an independent inspector retained
by Perkin-Elmer. If in dispute, such records shall be kept until the dispute is
settled. Inspection shall be at Perkin-Elmer's expense, unless the inspector
concludes that the amount payable that is stated in a report is understated by
five percent (5%) or more, in which case expenses shall be paid by Thermal
Cycler Supplier.

         3.4 Thermal Cycler Supplier shall within thirty (30) days after the
first of each January, April, July and October deliver to Perkin-Elmer a true
and accurate accounting report. This report shall give such particulars of the
business conducted by Thermal Cycler Supplier during the preceding three (3)
calendar months as are pertinent to accounting under this Agreement and shall be
in accordance with, and include all information specified in, the royalty report
form attached hereto as Appendix A.


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                                      -5-
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         The correctness and completeness of each report shall be attested to in
writing by the responsible financial officer of Thermal Cycler Supplier or by
Thermal Cycler Supplier's external auditor.

         3.5 Simultaneously with the delivery of each royalty report, Thermal
Cycler Supplier shall pay to Perkin-Elmer the monies then due under this
Agreement for the period covered by the report. Each report and payment shall be
sent by the due date to the following address:

                         Applied Biosystems Division
                         The Perkin-Elmer Corporation
                         850 Lincoln Centre Drive
                         Foster City, California, U.S.A. 94404
                         Attention: Director of Licensing

or to any address that Perkin-Elmer may advise in writing.

         3.6 If Thermal Cycler Supplier shall fail to pay any amount owing under
this Agreement by the due date, the amount owed shall bear interest at two
percent (2%) over the Citibank NA base lending rate ("prime rate") from the due
date until paid, provided, however, that if this interest rate is held to be
unenforceable for any reason, the interest rate shall be the maximum rate
allowed by law at the time the payment is due.

         3.7 Failure of Thermal Cycler Supplier to pay any amount specified
under this Agreement within thirty (30) days after the due date will give
Perkin-Elmer the right to terminate under Section 6.7.

         4. PAST SALES AND ACTIVITIES

         4.1 Upon execution of this Agreement Thermal Cycler Supplier shall pay
to Perkin-Elmer the sum of $*** which shall be due and owing on that date.
In consideration therefor all thermal cyclers delivered or invoiced by Thermal
Cycler Supplier prior to the Effective Date of this Agreement shall be
considered Authorized Thermal Cyclers, subject to the conditions of Sections 4.2



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                                      -6-
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and 5.3; and all earlier use of such thermal cyclers by customers, direct or
indirect, of Thermal Cycler Supplier shall be deemed to have been use of a
thermal cycler within the grant of this Agreement.

         4.2 Thermal Cycler Supplier shall send to the original end-user
customers of the thermal cyclers that are the subject of Section 3.1 or Section
4.1 but were shipped without labels specified in Section 5.1 Authorized Thermal
Cycler notices in accordance with Section 5.1 with a means reasonably
satisfactory to Perkin-Elmer to relate each such notice to the appropriate
thermal cycler. Any such thermal cycler not having an authorization notice by
July 31, 1995 shall cease to be an Authorized Thermal Cycler unless Thermal
Cycler Supplier establishes to the reasonable satisfaction of Perkin-Elmer that
(a) the thermal cycler falls within Section 4.1 and (b) the Authorized Thermal
Cycler notice for the thermal cycler has not been applied to another instrument.

         5. AUTHORIZATION NOTICE

         5.1 Thermal Cycler Supplier agrees to include in the front of the
user's manual for each Authorized Thermal Cycler, and for no other thermal
cycler, a Notice as specified from time to time by Perkin-Elmer. Unless and
until Perkin-Elmer reasonably instructs differently, the Notice shall be:

                            AUTHORIZED THERMAL CYCLER

               THIS INSTRUMENT, SERIAL NO.____, IS IN AUTHORIZED THERMAL CYCLER.
               ITS PURCHASE PRICE INCLUDES THE UP-FRONT FEE COMPONENT OF A
               LICENSE UNDER THE PATENTS ON THE POLYMERASE CHAIN REACTION (PCR)
               PROCESS, WHICH ARE OWNED BY HOFFMANN-LA ROCHE INC. AND F.
               HOFFMANN-LA ROCHE LTD, TO PRACTICE THE PCR PROCESS FOR INTERNAL
               RESEARCH AND DEVELOPMENT USING THIS INSTRUMENT. THE
               RUNNING-ROYALTY COMPONENT OF THAT LICENSE MAY BE PURCHASED FROM
               PERKIN-ELMER OR OBTAINED BY PURCHASING AUTHORIZED REAGENTS. THIS
               INSTRUMENT IS ALSO AN AUTHORIZED THERMAL CYCLER FOR USE WITH
               APPLICATIONS LICENSES AVAILABLE FROM PERKIN-ELMER. ITS USE WITH
               AUTHORIZED REAGENTS ALSO PROVIDES A LIMITED PCR LICENSE IN
               ACCORDANCE WITH THE LABEL RIGHTS ACCOMPANYING SUCH REAGENTS.
               PURCHASE OF THIS PRODUCT DOES NOT ITSELF CONVEY TO THE PURCHASER
               A COMPLETE LICENSE OR RIGHT TO PERFORM THE PCR PROCESS. FURTHER
               INFORMATION ON PURCHASING LICENSES TO PRACTICE THE PCR PROCESS
               MAY BE OBTAINED BY CONTACTING THE DIRECTOR OF LICENSING AT THE
               PERKIN-ELMER CORPORATION, 850 LINCOLN CENTRE DRIVE, FOSTER CITY,
               CALIFORNIA 94404.

               PERKIN-ELMER DOES NOT GUARANTEE THE PERFORMANCE OF THIS
               INSTRUMENT.


                                      -7-
<PAGE>

         5.2 Thermal Cycler Supplier agrees to affix permanently and prominently
to each Authorized Thermal Cycler the designation "Authorized Thermal Cycler,"
its Serial Number and a direction to consult the user's manual for license
information.

         5.3 Thermal Cycler Supplier further agrees to instruct the ultimate
purchaser that transfer of the thermal cycler without the Serial Number or the
Notice shall automatically terminate the authorization granted by this Agreement
and the thermal cycler shall cease to be an Authorized Thermal Cycler.

         5.4 To avoid confusion among thermal cycler users, Thermal Cycler
Supplier agrees not to designate or refer to its Authorized Thermal Cyclers as
"licensed" under the Amplification Patent Rights or "licensed" for PCR. However,
Perkin-Elmer agrees that Thermal Cycler Supplier may designate or refer to its
Authorized Thermal Cyclers as carrying up-front license rights under the
Amplification Patent Rights in a manner that fairly does not suggest that use of
an Authorized Thermal Cycler conveys a full license under the Amplification
Patent Rights.

         6. TERM AND TERMINATION

         6.1 This Agreement, unless sooner terminated, shall continue until the
expiration of the last-to-expire of the Amplification Patent Rights.

         6.2 This Agreement shall terminate upon a holding of invalidity or
unenforceability of all claims of the Amplification Patent Rights by a final
court decision from which no appeal is or can be taken.

         6.3 Thermal Cycler Supplier may terminate this Agreement for any reason
by giving written notice to Perkin-Elmer and ceasing to advertise or promote its
thermal cyclers as Authorized Thermal Cyclers. Such termination shall be
effective ninety (90) days after said notice or cessation, whichever is later.


                                      -8-
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         6.4 The decision of a Court or Administrative body finding Perkin-Elmer
liable or culpable due to Thermal Cycler Supplier's manufacture, sale or
distribution of Authorized Thermal Cyclers shall give Perkin-Elmer the right to
terminate this Agreement immediately upon notice.

         6.5 This Agreement shall terminate upon (i) an adjudication of Thermal
Cycler Supplier as bankrupt or insolvent, or Thermal Cycler Supplier's admission
in writing of its inability to pay its obligations as they mature; (a) an
assignment by Thermal Cycler Supplier for the benefit of creditors; (iii) the
appointment of, or Thermal Cycler Supplier's applying for or consenting to the
appointment of a receiver, trustee or similar officer for a substantial part of
its property; (iv) the institution of or any act of Thermal Cycler Supplier
instituting any bankruptcy, insolvency arrangement, or similar proceeding; (v)
the issuance or levy of any judgment, writ, warrant of attachment or execution
or similar process against a substantial part of the property of Thermal Cycler
Supplier; or (vi) loss of Thermal Cycler Suppliers federal or state licenses,
permits or accreditation necessary for distribution of Authorized Thermal
Cyclers.

         6.6 Perkin-Elmer may terminate this Agreement immediately on notice
upon any change in the ownership or control of Thermal Cycler Supplier or of its
assets. For such purposes, a "change in ownership or control" shall mean that
***% or more of the voting stock of Thermal Cycler Supplier becomes subject to
the ownership or control of a person or entity, or any related group of persons
or entities acting in concert, which person(s) or entity(ies) did not own or
control any portion of the voting stock on the Effective Date hereof.
Perkin-Elmer shall have the same right to terminate upon any transfer of ***% or
more of the assets of Thermal Cycler Supplier. Thermal Cycler Supplier warrants
that no portion of its voting stock was owned on the Effective Date hereof by
any instrument manufacturer or biotechnology company.

         6.7 Upon any breach of or default of a material term under this
Agreement by Thermal Cycler Supplier, Perkin-Elmer may terminate this Agreement
upon thirty (30) days' written notice. Perkin-Elmer will withdraw such notice
if, during the notice period, Thermal Cycler Supplier fully cures such breach or
default to Perkin-Elmer's reasonable satisfaction.


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        6.8 Upon expiration or termination of this Agreement, all rights granted
to Thermal Cycler Supplier shall revert to or be retained by Perkin-Elmer.

        6.9 Thermal Cycler Supplier's obligations to report and pay royalties as
to activities under the Agreement shall survive termination or expiration.

        7. CONFIDENTIALITY - PUBLICITY

        7.1 In advertisements, catalogs, brochures, sales literature and
promotional literature for Authorized Thermal Cyclers, Thermal Cycler Supplier
shall state the following prominently in type and location:

               Practice of the patented polymerase chain reaction (PCR) process
               requires a license. Stratagene's thermal cycler is an Authorized
               Thermal Cycler. Its use with Authorized Reagents provides a
               limited PCR license in accordance with the label rights
               accompanying such reagents. It may also be used with PCR licenses
               available from The Perkin-Elmer Corporation.

        7.2 With respect to Thermal Cycler Supplier's distribution of any
written information to Third Parties, including but not limited to advertising,
brochures, catalogs, promotional and sales material, and public relations
material, Perkin-Elmer shall have the right to prescribe changes regarding
references to, or descriptions of: Perkin-Elmer, PCR, the Amplification Patent
Rights, the PCR Instrument Patents, PCR licenses or authorizations, or this
Agreement. Thermal Cycler Supplier agrees to comply with Perkin-Elmer's
reasonable prescriptions.

        7.3 Except as provided in Sections 7.1 and 7.2, Thermal Cycler Supplier
shall, to the extent reasonably practicable, maintain the confidentiality of the
provisions of this Agreement and shall refrain from disclosing the terms of this
Agreement without the prior written consent of Perkin-Elmer, except to the
extent Thermal Cycler Supplier concludes in good faith that such disclosure is
required under applicable law or regulation, in which case Perkin-Elmer shall be
notified in advance.



                                      -10-
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        8. COMPLIANCE AND QUALITY

        8.1 In the exercise of any and all rights and in performance hereunder,
it shall be the duty of the Thermal Cycler Supplier, not Perkin-Elmer, to
comply fully with all applicable laws, regulations and ordinances and to obtain
and keep in affect licenses, permits and other governmental approvals (federal,
state or local) necessary or appropriate to carry on activities hereunder.

        8.2 Perkin-Elmer does not approve or endorse thermal cyclers of Thermal
Cycler Supplier in any way or for any purpose, including PCR. Quality and
quality control with respect to suitability for PCR, according to standards and
requirements that may exist in the marketplace from time to time, are the sole
responsibility of Thermal Cycler Supplier.

        9. ASSIGNMENT

        9.1 This Agreement shall not be assigned by Thermal Cycler Supplier
(including without limitation any assignment or transfer that would arise from a
sale or transfer of Thermal Cycler Supplier's business).

        9.2 Perkin-Elmer may assign all or any part of its rights and
obligations under this Agreement at any time without the consent of Thermal
Cycler Supplier. Thermal Cycler Supplier agrees to execute such further
acknowledgments or other instruments as Perkin-Elmer may reasonably request in
connection with such assignment.

        10. NEGATION OF WARRANTIES AND INDEMNITY

        10.1 Nothing in this Agreement shall be construed as: (a) a warranty or
representation by Perkin-Elmer as to the validity or scope of any patent; (b) a
warranty or representation that the practice under the Amplification Patent
Rights is or will be free from infringement of patents of Third Parties; (c) an
authority or obligation to sublicense or to sue Third Parties for infringement;
(d) except as expressly set forth herein, conferring the right to use in
advertising, publicity or otherwise, in any form, the name of, or any trademark
or trade name of, Perkin-Elmer or Roche; (e) conferring



                                      -11-
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by implication, estoppel or otherwise any license, immunity or right under any
patent owned by or licensed to Perkin-Elmer or Roche other than those specified,
regardless of whether such patent is dominant or subordinate to the
Amplification Patent Rights; (f) an obligation to furnish any know-how; or (g)
creating any agency, partnership, joint venture or similar relationship between
Perkin-Elmer or Roche and Thermal Cycler Supplier.

        10.2 PERKIN-ELMER MAKES NO EXPRESS OR IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

        10.3 Thermal Cycler Supplier agrees to take all reasonable precautions
to prevent death, personal injury, illness and property damage from the use of
Authorized Thermal Cyclers. Thermal Cycler Supplier shall assume full
responsibility for its operation under the Amplification Patent Rights, the
manufacture of Authorized Thermal Cyclers and the use thereof and shall defend,
indemnify and hold Perkin-Elmer harmless from and against all liability,
demands, damages, expenses (including attorneys' fees) and losses for death,
personal injury, illness, property damage or any other injury or damage,
including any damages or expenses arising in connection with state or federal
regulatory action, in view of the use by Thermal Cycler Supplier, its officers,
directors, agents and employees of the Amplification Patent Rights, and the
manufacture and use of Authorized Thermal Cyclers except that Thermal Cycler
Supplier shall not be liable to Perkin-Elmer for injury or damage arising solely
out of or resulting from Perkin-Elmer's negligence, willful conduct or
intentional acts or intentional omissions with respect to a Perkin-Elmer-
supplied product.


        11. MOST FAVORED LICENSEE

        11.1 If after signature of this Agreement (a) Perkin-Elmer grants to any
unrelated Third Party thermal cycler supplier other than Roche a license of the
instant type, that is, a Thermal Cycler Supplier Authorization Agreement
granting rights only under the Amplification Patent Rights, or a license of the
type previously offered to Thermal Cycler Supplier, that is, a Thermal Cycler
Supplier Agreement granting rights under the Amplification Patent Rights and the
PCR Instrument Patents but which includes therein a per thermal cycler royalty
payment only under the Amplification Patent



                                      -12-
<PAGE>

Rights, and (b) the grant only under the Amplification Patent Rights is of
substantially the same scope as granted to Thermal Cycler Supplier herein
***, then Perkin-Elmer shall promptly notify Thermal Cycler Supplier of ***, and
Thermal Cycler Supplier shall have the right and option to ***. Thermal Cycler
Supplier's right to *** shall extend only for so long as and shall be
conditioned on Thermal Cycler Supplier's acceptance of all the conditions,
favorable or unfavorable, applicable to rights under only the Amplification
Patent Rights under which ***.  Upon Thermal Cycler Supplier's acceptance of
***, the *** shall be effective as to Thermal Cycler Supplier on the date of
***.

        11.2 If within *** after signature of this Agreement, Perkin-Elmer
grants to any unrelated Third Party thermal cycler supplier other than Roche a
license under the Amplification Patent Rights only and of substantially the same
scope as granted to Thermal Cycler Supplier hereunder ***, Perkin-Elmer shall
promptly notify Thermal Cycler Supplier of ***, and Thermal Cycler Supplier
shall have the right and option, exercisable within ninety (90) days of
notification, to ***. Thermal Cycler Supplier's right to *** shall extend only
for so long as and shall be conditioned on Thermal Cycler Supplier's acceptance
of all the same conditions, favorable or unfavorable, exclusive of payment for
the past, under which *** shall be available to such other Third Party. If
Thermal Cycler Supplier elects to ***, Thermal Cycler Supplier shall receive
credit for the license issue fee paid hereunder.  Other financial terms shall
apply to financial obligations incurred by Thermal Cycler Supplier after the
date of ***.


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                                      -13-
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        11.3 If after signature of this Agreement, Perkin-Elmer grants to an
unrelated Third Party thermal cycler supplier other than Roche a license of the
type previously offered to Thermal Cycler Supplier, that is, a Thermal Cycler
Supplier Agreement granting combined rights under the Amplification Patent
Rights and the PCR Instrument Patents ("Combined License"), ***, then
Perkin-Elmer shall promptly notify Thermal Cycler Supplier of the *** and the
*** therefor, and Thermal Cycler Supplier shall have the right and option,
exercisable within *** after notification, to ***, retroactive to the Effective
Date of this Agreement, as follows: Thermal Cycler Supplier shall receive credit
for all payments made hereunder; all financial obligations of Thermal Cycler
Supplier shall be recalculated according to the ***, and payment for the past,
exclusive of any credit, shall be ***.

        11.4 None of Section 11.1 through 11.3 shall apply to a Third Party
grant or license for which Perkin-Elmer and/or Roche shall ***, for example,
such as ***, as part of the ***.


        12. GENERAL

        12.1 This Agreement constitutes the entire agreement between the Parties
as to the subject matter hereof, and all prior negotiations, representations,
agreements and understandings are merged into, extinguished by and completely
expressed by it. This Agreement may be modified or amended only by a writing
executed by authorized officers of each of the Parties.

        12.2 Any notice required or permitted to be given by this Agreement
shall be given by postpaid, first class, registered or certified mail, or by
courier or facsimile, property addressed to the other party at the respective
address as shown below:


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                                      -14-
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If to Perkin-Elmer:

                        Applied Biosystems Division
                        The Perkin-Elmer Corporation
                        850 Lincoln Centre Drive
                        Foster City, California U.S.A. 94404
                        Att'n.: Director of Licensing

If to Thermal Cycler Supplier:

                        Stratagene
                        11011 North Torrey Pines Road
                        La Jolla, California U.S.A. 92037
                        Att'n.: Chief Executive Officer

Either party may change its address by providing notice to the other. A notice
shall be deemed given four (4) full business days after the day of mailing, or
one full day after the date of delivery to the courier, or the date of facsimile
transmission, as the case may be.

        12.3 Governing Law and Venue. This Agreement shall be deemed made in the
County and State of New York, and it shall be construed and enforced in
accordance with the law of the State of New York. The Parties agree that the
exclusive jurisdiction and venue for any dispute or controversy arising from
this Agreement shall be in the state or federal courts in New York.

        12.4 Arbitration

        (a) If arbitration is demanded within the applicable statute of
limitations for commencement of an action in a New York court, disputes
concerning solely the determination of certain facts shall be settled by final
and binding arbitration at a mutually convenient location in the State of New
York pursuant to the commercial arbitration rules of the American Arbitration
Association in accordance with the following procedure: the arbitration tribune
shall consist of three arbitrators, one selected by each party and the third,
the chairman, selected by those two within sixty (60) days of the filing of the
answer.

        (b) Factual disputes subject to arbitration under this section include:
royalty payments due under Section 3.1 or Section 3.3, Thermal Cycler Supplier's
compliance with Sections 5.2 and



                                      -15-
<PAGE>

5.3, Thermal Cycler Supplier's compliance with the second sentence of Section
5.4, the occurrence of facts triggering expiration under Section 6.1 or
termination under Section 6.2 or Section 6.6, and Thermal Cycler Supplier's
right to notification and option under Article 11. Other factual disputes and
issues of law, including but not limited to the validity, enforceability, scope
or infringement of any patent, shall not be subject to arbitration under this
section.

        (c) The decision of the arbitration tribunal shall be final and judgment
thereon may be entered in any competent state or federal court in New York for
judicial acceptance of such award and order of enforcement. Each party hereby
submits itself to the jurisdiction of the state and federal courts in New York
for the entry of judgment with respect to decisions of arbitrators hereunder.

        12.5 Negotiation. Prior to commencing any lawsuit with respect to any
claim or controversy under this Agreement or the interpretation thereof, or
prior to demanding arbitration under Section 12.4, each party agrees to consult
with the other party to attempt to resolve the claim or controversy. The Parties
agree to attempt in good faith to achieve a resolution through consultation.

        12.6 Nothing in this Agreement shall be construed to require the
commission of any act contrary to law, and wherever there is any conflict
between any provision of this Agreement or concerning the legal right of the
Parties to enter into this contract and any statute, law or ordinance, the
latter shall prevail, but the provision shall be limited only to the extent
necessary.

        12.7 If any provision of this Agreement is held or discovered to both
parties' satisfaction to be illegal, invalid or unenforceable in any
jurisdiction or to render any patent in that jurisdiction unenforceable, the
provisions as it applies to that jurisdiction only shall be replaced
automatically, as part of the document, by a provision as similar in terms as
possible but not subject to such infirmity, in order to achieve the intent of
the parties to the extent possible. In any event, as to that jurisdiction all
other provisions of this Agreement shall be deemed valid and enforceable to the
full extent possible.



                                      -16-
<PAGE>

        IN WITNESS WHEREOF, the Parties hereto, have duly executed this
Agreement on the date(s) indicated below.




THE PERKIN-ELMER CORPORATION                 STRATAGENE


By:  /s/ MICHAEL W. HUNKAPILLER              By: /s/ JOSEPH SORGE
   --------------------------------             --------------------------------
     Michael W. Hunkapiller, Ph.D.


Title:    Vice President                     Title:    CEO
      -----------------------------                 ----------------------------


Date:     4/20/95                            Date:     4/19/95
     ------------------------------               ------------------------------



                                      -17-
<PAGE>
APPENDIX A

                             SUMMARY ROYALTY REPORT
                THERMAL CYCLER SUPPLIER AUTHORIZATION AGREEMENT
                      FOR THE PERIOD __/__/95 TO __/__/95

THERMAL CYCLER(TC) SUPPLIER: STRATAGENE     FOR SALES IN THE COUNTRY OF_________

LICENSE NUMBER: __________      EFFECTIVE DATE: __/__/__

     [ ] Check here if there were no sales for this period

<Table>
<Caption>
--------------------------------------------------------------------------------------------------------------------------
                                                                       ROYALTY (IN$) PER TC:
     TC MODEL NO.        NO. OF TCS     SAMPLE CAPACITY     *** + *** X (MAX. SAMPLE CAPACITY - ***)/*** *    ROYALTY DUE
--------------------------------------------------------------------------------------------------------------------------
<S>                      <C>            <C>                 <C>                                               <C>
1.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
2.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
3.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
4.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
5.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
6.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
                                                                                          TOTAL ROYALTY EARNED
                                                                                                                ----------
                                                                                          APPLICABLE CREDIT**
                                                                                                                ----------
                                                                                          ROYALTY PAYMENT DUE
                                                                                                                ----------
</Table>

* The fraction (max. sample capacity - ***)/*** is rounded to the next higher
whole number
** Please attach supporting or supplemental data to this sheet

I HEREBY CERTIFY THE INFORMATION SET FORTH ABOVE IS CORRECT AND COMPLETE WITH
RESPECT TO THE AMOUNTS DUE UNDER THE APPLICABLE LICENSE AGREEMENT.

By:                       Title:                        Date:
   ---------------------        -----------------------      -------------------
Name (please print):
                    ------------------------------
================================================================================
THE PERKIN-ELMER CORPORATION
SEND REPORT TO:
Director of Licensing, Applied Biosystems Division, The Perkin-Elmer Corp., 850
Lincoln Centre Dr., Foster City, CA 94404



*** Certain information on this page has been omitted and filed separately with
    the Commission. Confidential treatment has been requested with respect to
    the omitted portions.



TC Supplier Authorization Agreement    -18-                  Stratagene -4-14-95

<PAGE>
APPENDIX A - page 2

                             SUMMARY ROYALTY REPORT
                THERMAL CYCLER SUPPLIER AUTHORIZATION AGREEMENT
                      FOR THE PERIOD __/__/9_ TO __/__/9_

THERMAL CYCLER(TC) SUPPLIER: STRATAGENE     FOR SALES IN THE COUNTRY OF_________

LICENSE NUMBER: __________      EFFECTIVE DATE: __/__/__

     [ ] Check here if there were no sales for this period

<Table>
<Caption>
--------------------------------------------------------------------------------------------------------------------------
                                                                       ROYALTY (IN$) PER TC:
     TC MODEL NO.        NO. OF TCS     SAMPLE CAPACITY     *** + *** X (MAX. SAMPLE CAPACITY - ***)/*** *    ROYALTY DUE
--------------------------------------------------------------------------------------------------------------------------
<S>                      <C>            <C>                 <C>                                               <C>
1.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
2.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
3.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
4.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
5.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
6.
  ------------------     ---------      ---------------     ------------------------------------------          ----------
                                                                                          TOTAL ROYALTY EARNED
                                                                                                                ----------
                                                                                          APPLICABLE CREDIT**
                                                                                                                ----------
                                                                                          ROYALTY PAYMENT DUE
                                                                                                                ----------
</Table>

* The fraction (max. sample capacity - ***)/*** is rounded to the next higher
whole number
** Please attach supporting or supplemental data to this sheet

I HEREBY CERTIFY THE INFORMATION SET FORTH ABOVE IS CORRECT AND COMPLETE WITH
RESPECT TO THE AMOUNTS DUE UNDER THE APPLICABLE LICENSE AGREEMENT.

By:                       Title:                        Date:
   ---------------------        -----------------------      -------------------
Name (please print):
                    ------------------------------
================================================================================
THE PERKIN-ELMER CORPORATION
SEND REPORT TO:
Director of Licensing, Applied Biosystems Division, The Perkin-Elmer Corp., 850
Lincoln Centre Dr., Foster City, CA 94404



*** Certain information on this page has been omitted and filed separately with
    the Commission. Confidential treatment has been requested with respect to
    the omitted portions.



TC Supplier Authorization Agreement    -19-                  Stratagene -4-14-95