<PAGE>

                                                                   EXHIBIT 10.43

                                    EXHIBIT A

NEITHER THESE SECURITIES NOR THE SECURITIES FOR WHICH THESE SECURITIES ARE
EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR
THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM
REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES
ACT"), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN
AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION
REQUIREMENTS OF THE SECURITIES ACT AND IN COMPLIANCE WITH APPLICABLE STATE
SECURITIES OR BLUE SKY LAWS. THESE SECURITIES AND THE SECURITIES ISSUABLE UPON
EXERCISE OF THESE SECURITIES MAY BE PLEDGED IN CONNECTION WITH A BONA FIDE
MARGIN ACCOUNT OR OTHER LOAN SECURED BY SUCH SECURITIES.

                             LYNX THERAPEUTICS, INC.

                                     WARRANT

Warrant No. [ ]                                           Dated: December , 2003

         Lynx Therapeutics, Inc., a Delaware corporation (the "COMPANY"), hereby
certifies that, for value received, [Name of Holder] or its registered assigns
(the "HOLDER"), is entitled to purchase from the Company up to a total of [ ](1)
shares of common stock, $0.01 par value per share (the "COMMON STOCK"), of the
Company (each such share, a "WARRANT SHARE" and all such shares, the "WARRANT
SHARES") at an exercise price equal to $6.25 per share (as adjusted from time to
time as provided in Section 9, the "EXERCISE PRICE"), at any time and from time
to time from and after the date hereof and through and including the date that
is 270 days after the Effective Date (the "EXPIRATION DATE"), and subject to the
following terms and conditions. This Warrant (this "WARRANT") is one of a series
of similar warrants issued pursuant to that certain Securities Purchase
Agreement, dated as of the date hereof, by and among the Company and the
Purchasers identified therein (the "PURCHASE AGREEMENT"). All such warrants are
referred to herein, collectively, as the "WARRANTS."

         1.       Definitions. In addition to the terms defined elsewhere in
this Warrant, capitalized terms that are not otherwise defined herein have the
meanings given to such terms in the Purchase Agreement.

         2.       Registration of Warrant. The Company shall register this
Warrant, upon records to be maintained by the Company for that purpose (the
"WARRANT REGISTER"), in the name of the record Holder hereof from time to time.
The Company may deem and treat the registered Holder of this Warrant as the
absolute owner hereof for the purpose of any exercise hereof or any distribution
to the Holder, and for all other purposes, absent actual notice to the contrary.

--------
(1) Pro-rata of 200,000 shares.

<PAGE>

         3.       Registration of Transfers. The Company shall register the
transfer of any portion of this Warrant in the Warrant Register, upon surrender
of this Warrant, with the Form of Assignment attached hereto duly completed and
signed, to the Transfer Agent or to the Company at its address specified herein.
Upon any such registration or transfer, a new warrant to purchase Common Stock,
in substantially the form of this Warrant (any such new warrant, a "NEW
WARRANT"), evidencing the portion of this Warrant so transferred shall be issued
to the transferee and a New Warrant evidencing the remaining portion of this
Warrant not so transferred, if any, shall be issued to the transferring Holder.
The acceptance of the New Warrant by the transferee thereof shall be deemed the
acceptance by such transferee of all of the rights and obligations of a holder
of a Warrant.

         4.       Exercise and Duration of Warrants.

                  (a)      This Warrant shall be exercisable by the registered
Holder at any time and from time to time on or after the date hereof to and
including the Expiration Date. At 6:30 P.M., New York City time on the
Expiration Date, the portion of this Warrant not exercised prior thereto shall
be and become void and of no value.

                  (b)      A Holder may exercise this Warrant by delivering to
the Company (i) an exercise notice, in the form attached hereto (the "EXERCISE
NOTICE"), appropriately completed and duly signed, and (ii) payment of the
Exercise Price for the number of Warrant Shares as to which this Warrant is
being exercised , and the date such items are delivered to the Company (as
determined in accordance with the notice provisions hereof) is an "EXERCISE
DATE." The Holder shall not be required to deliver the original Warrant in order
to effect an exercise hereunder. Execution and delivery of the Exercise Notice
shall have the same effect as cancellation of the original Warrant and issuance
of a New Warrant evidencing the right to purchase the remaining number of
Warrant Shares.

         5.       Delivery of Warrant Shares.

                  (a)      Upon exercise of this Warrant, the Company shall
promptly (but in no event later than three Trading Days after the Exercise Date)
issue or cause to be issued and cause to be delivered to or upon the written
order of the Holder and in such name or names as the Holder may designate, a
certificate for the Warrant Shares issuable upon such exercise. The Holder, or
any Person so designated by the Holder to receive Warrant Shares, shall be
deemed to have become holder of record of such Warrant Shares as of the Exercise
Date. The Company shall, upon request of the Holder, use its best efforts to
deliver Warrant Shares hereunder electronically through the Depository Trust
Corporation or another established clearing corporation performing similar
functions.

                  (b)      This Warrant is exercisable, either in its entirety
or, from time to time, for a portion of the number of Warrant Shares. Upon
surrender of this Warrant following one or more partial exercises, the Company
shall issue or cause to be issued, at its expense, a New Warrant evidencing the
right to purchase the remaining number of Warrant Shares.

                  (c)      The Company's obligations to issue and deliver
Warrant Shares in accordance with the terms hereof are absolute and
unconditional, irrespective of any action or

                                       2

<PAGE>

inaction by the Holder to enforce the same, any waiver or consent with respect
to any provision hereof, the recovery of any judgment against any Person or any
action to enforce the same, or any setoff, counterclaim, recoupment, limitation
or termination, or any breach or alleged breach by the Holder or any other
Person of any obligation to the Company or any violation or alleged violation of
law by the Holder or any other Person, and irrespective of any other
circumstance which might otherwise limit such obligation of the Company to the
Holder in connection with the issuance of Warrant Shares. Nothing herein shall
limit a Holder's right to pursue any other remedies available to it hereunder,
at law or in equity including, without limitation, a decree of specific
performance and/or injunctive relief with respect to the Company's failure to
timely deliver certificates representing shares of Common Stock upon exercise of
the Warrant as required pursuant to the terms hereof.

         6.       Charges, Taxes and Expenses. Issuance and delivery of
certificates for shares of Common Stock upon exercise of this Warrant shall be
made without charge to the Holder for any issue or transfer tax, withholding
tax, transfer agent fee or other incidental tax or expense in respect of the
issuance of such certificates, all of which taxes and expenses shall be paid by
the Company; provided, however, that the Company shall not be required to pay
any tax which may be payable in respect of any transfer involved in the
registration of any certificates for Warrant Shares or Warrants in a name other
than that of the Holder or an Affiliate thereof. The Holder shall be responsible
for all other tax liability that may arise as a result of holding or
transferring this Warrant or receiving Warrant Shares upon exercise hereof.

         7.       Replacement of Warrant. If this Warrant is mutilated, lost,
stolen or destroyed, the Company shall issue or cause to be issued in exchange
and substitution for and upon cancellation hereof, or in lieu of and
substitution for this Warrant, a New Warrant, but only upon receipt of evidence
reasonably satisfactory to the Company of such loss, theft or destruction and
customary and reasonable indemnity, if requested. Applicants for a New Warrant
under such circumstances shall also comply with such other reasonable
regulations and procedures and pay such other reasonable third-party costs as
the Company may prescribe.

         8.       Reservation of Warrant Shares. The Company covenants that it
will at all times reserve and keep available out of the aggregate of its
authorized but unissued and otherwise unreserved Common Stock, solely for the
purpose of enabling it to issue Warrant Shares upon exercise of this Warrant as
herein provided, the number of Warrant Shares which are then issuable and
deliverable upon the exercise of this entire Warrant, free from preemptive
rights or any other contingent purchase rights of persons other than the Holder
(taking into account the adjustments and restrictions of Section 9). The Company
covenants that all Warrant Shares so issuable and deliverable shall, upon
issuance and the payment of the applicable Exercise Price in accordance with the
terms hereof, be duly and validly authorized, issued and fully paid and
nonassessable. The Company will take all such action as may be necessary to
assure that such shares of Common Stock may be issued as provided herein without
violation of any applicable law or regulation, or of any requirements of any
securities exchange or automated quotation system upon which the Common Stock
may be listed.

                                        3

<PAGE>

         9.       Certain Adjustments. The Exercise Price and number of Warrant
Shares issuable upon exercise of this Warrant are subject to adjustment from
time to time as set forth in this Section 9.

                  (a)      Stock Dividends and Splits. If the Company, at any
time while this Warrant is outstanding, (i) pays a stock dividend on its Common
Stock or otherwise makes a distribution on any class of capital stock that is
payable in shares of Common Stock, (ii) subdivides outstanding shares of Common
Stock into a larger number of shares, or (iii) combines outstanding shares of
Common Stock into a smaller number of shares, then in each such case the
Exercise Price shall be multiplied by a fraction of which the numerator shall be
the number of shares of Common Stock outstanding immediately before such event
and of which the denominator shall be the number of shares of Common Stock
outstanding immediately after such event. Any adjustment made pursuant to clause
(i) of this paragraph shall become effective immediately after the record date
for the determination of stockholders entitled to receive such dividend or
distribution, and any adjustment pursuant to clause (ii) or (iii) of this
paragraph shall become effective immediately after the effective date of such
subdivision or combination. Simultaneously with any adjustment to the Exercise
Price pursuant to this paragraph (a) of Section, the number of Warrant Shares
that may be purchased upon exercise of this Warrant shall be increased or
decreased proportionately, so that after such adjustment the aggregate Exercise
Price payable hereunder for the increased or decreased number of Warrant Shares
shall be the same as the aggregate Exercise Price in effect immediately prior to
such adjustment.

                  (b)      Pro Rata Distributions. If the Company, at any time
while this Warrant is outstanding, distributes to holders of Common Stock (i)
evidences of its indebtedness, (ii) any security (other than a distribution of
Common Stock covered by the preceding paragraph), (iii) rights or warrants to
subscribe for or purchase any security, or (iv) any other asset (in each case,
"DISTRIBUTED PROPERTY"), then in each such case the Exercise Price in effect
immediately prior to the record date fixed for determination of stockholders
entitled to receive such distribution shall be adjusted (effective on such
record date) to equal the product of such Exercise Price times a fraction of
which the denominator shall be the average of the Closing Prices for the five
Trading Days immediately prior to (but not including) such record date and of
which the numerator shall be such average less the then fair market value of the
Distributed Property distributed in respect of one outstanding share of Common
Stock, as determined by the Company's independent certified public accountants
that regularly examine the financial statements of the Company (an "APPRAISER").
In such event, the Holder, after receipt of the determination by the Appraiser,
shall have the right to select an additional appraiser (which shall be a
nationally recognized accounting firm), in which case such fair market value
shall be deemed to equal the average of the values determined by each of the
Appraiser and such appraiser.

                  (c)      Fundamental Transactions. If, at any time while this
Warrant is outstanding, (i) the Company effects any merger or consolidation of
the Company with or into another Person, (ii) the Company effects any sale of
all or substantially all of its assets in one or a series of related
transactions, (iii) any tender offer or exchange offer (whether by the Company
or another Person) is completed pursuant to which holders of Common Stock are
permitted to tender or exchange their shares for other securities, cash or
property, or (iv) the Company effects

                                        4

<PAGE>

any reclassification of the Common Stock or any compulsory share exchange
pursuant to which the Common Stock is effectively converted into or exchanged
for other securities, cash or property (other than as a result of a subdivision
or combination of shares of Common Stock covered by Section 9(a) above) (in any
such case, a "FUNDAMENTAL TRANSACTION"), then the Holder shall have the right
thereafter to receive, upon exercise of this Warrant, the same amount and kind
of securities, cash or property as it would have been entitled to receive upon
the occurrence of such Fundamental Transaction if it had been, immediately prior
to such Fundamental Transaction, the holder of the number of Warrant Shares then
issuable upon exercise in full of this Warrant (the "ALTERNATE CONSIDERATION").
The aggregate Exercise Price for this Warrant will not be affected by any such
Fundamental Transaction, but the Company shall apportion such aggregate Exercise
Price among the Alternate Consideration in a reasonable manner reflecting the
relative value of any different components of the Alternate Consideration. If
holders of Common Stock are given any choice as to the securities, cash or
property to be received in a Fundamental Transaction, then the Holder shall be
given the same choice as to the Alternate Consideration it receives upon any
exercise of this Warrant following such Fundamental Transaction. At the Holder's
request, any successor to the Company or surviving entity in such Fundamental
Transaction shall issue to the Holder a new warrant consistent with the
foregoing provisions and evidencing the Holder's right to purchase the Alternate
Consideration for the aggregate Exercise Price upon exercise thereof. The terms
of any agreement pursuant to which a Fundamental Transaction is effected shall
include terms requiring any such successor or surviving entity to comply with
the provisions of this paragraph (c) and insuring that the Warrant (or any such
replacement security) will be similarly adjusted upon any subsequent transaction
analogous to a Fundamental Transaction. If any Fundamental Transaction
constitutes or results in a Change of Control, then at the request of the Holder
delivered before the 90th day after such Fundamental Transaction, the Company
(or any such successor or surviving entity) will purchase the Warrant from the
Holder for a purchase price, payable in cash within five Trading Days after such
request (or, if later, on the effective date of the Fundamental Transaction),
equal to the Black-Scholes value of the remaining unexercised portion of this
Warrant on the date of such request.

                  (d)      Subsequent Equity Sales.

                           (i)      If, at any time prior to the one year
         anniversary of the Closing Date, the Company or any Subsidiary issues
         additional shares of Common Stock or rights, warrants, options or other
         securities or debt convertible, exercisable or exchangeable for shares
         of Common Stock or otherwise entitling any Person to acquire shares of
         Common Stock (collectively, "COMMON STOCK EQUIVALENTS") at an effective
         net price to the Company per share of Common Stock (the "EFFECTIVE
         PRICE") less than the Exercise Price (as adjusted hereunder to such
         date), then the Exercise Price shall be reduced to equal the product of
         (A) the Exercise Price in effect immediately prior to such issuance of
         Common Stock or Common Stock Equivalents times (B) a fraction, the
         numerator of which is the sum of (1) the number of shares of Common
         Stock outstanding immediately prior to such issuance, plus (2) the
         number of shares of Common Stock which the aggregate Effective Price of
         the Common Stock issued (or deemed to be issued) would purchase at the
         Exercise Price, and the denominator of which is the aggregate number of
         shares of Common Stock outstanding or deemed to be outstanding

                                        5

<PAGE>

         immediately after such issuance. For purposes of this paragraph, in
         connection with any issuance of any Common Stock Equivalents, (A) the
         maximum number of shares of Common Stock potentially issuable at any
         time upon conversion, exercise or exchange of such Common Stock
         Equivalents (the "DEEMED NUMBER") shall be deemed to be outstanding
         upon issuance of such Common Stock Equivalents, (B) the Effective Price
         applicable to such Common Stock shall equal the minimum dollar value of
         consideration payable to the Company to purchase such Common Stock
         Equivalents and to convert, exercise or exchange them into Common Stock
         (net of any discounts, fees, commissions and other expenses), divided
         by the Deemed Number, and (C) no further adjustment shall be made to
         the Exercise Price upon the actual issuance of Common Stock upon
         conversion, exercise or exchange of such Common Stock Equivalents.

                           (ii)     If, at any time while this Warrant is
         outstanding, the Company or any Subsidiary issues Common Stock
         Equivalents with an Effective Price or a number of underlying shares
         that floats or resets or otherwise varies or is subject to adjustment
         based (directly or indirectly) on market prices of the Common Stock (a
         "FLOATING PRICE SECURITY"), then for purposes of applying the preceding
         paragraph in connection with any subsequent exercise, the Effective
         Price will be determined separately on each Exercise Date and will be
         deemed to equal the lowest Effective Price at which any holder of such
         Floating Price Security is entitled to acquire Common Stock on such
         Exercise Date (regardless of whether any such holder actually acquires
         any shares on such date).

                           (iii)    Notwithstanding the foregoing, no adjustment
         will be made under this paragraph (d) in respect to any issuance of
         Common Stock (A) upon exercise or conversion of any options or other
         securities described in Schedule 3.1(f) of the Purchase Agreement
         (provided that such exercise or conversion occurs in accordance with
         the terms thereof, without amendment or modification, and that the
         applicable exercise or conversion price or ratio is described in such
         schedule) or otherwise pursuant to any employee benefit plan described
         in Schedule 3.1(f) of the Purchase Agreement or hereafter adopted by
         the Company and approved by its stockholders, or (B) in connection with
         any grant of options to employees, officers, directors or consultants
         of the Company pursuant to a stock option plan duly adopted by the
         Company's board of directors or in respect of the issuance of Common
         Stock upon exercise of any such options.

                  (e)      Calculations. All calculations under this Section 9
shall be made to the nearest cent or the nearest 1/100th of a share, as
applicable. The number of shares of Common Stock outstanding at any given time
shall not include shares owned or held by or for the account of the Company, and
the disposition of any such shares shall be considered an issue or sale of
Common Stock.

                  (f)      Notice of Adjustments. Upon the occurrence of each
adjustment pursuant to this Section 9, the Company at its expense will promptly
compute such adjustment in accordance with the terms of this Warrant and prepare
a certificate setting forth such adjustment, including a statement of the
adjusted Exercise Price and adjusted number or type of Warrant Shares or other
securities issuable upon exercise of this Warrant (as applicable), describing
the transactions giving rise to such adjustments and showing in detail the facts
upon which such

                                        6

<PAGE>

adjustment is based. Upon written request, the Company will promptly deliver a
copy of each such certificate to the Holder and to the Company's Transfer Agent.

                  (g)      Notice of Corporate Events. If the Company (i)
declares a dividend or any other distribution of cash, securities or other
property in respect of its Common Stock, including without limitation any
granting of rights or warrants to subscribe for or purchase any capital stock of
the Company, (ii) authorizes or approves, enters into any agreement
contemplating any Fundamental Transaction or (iii) authorizes the voluntary
dissolution, liquidation or winding up of the affairs of the Company, then the
Company shall deliver to the Holder a notice describing the material terms and
conditions of such transaction, at least 15 calendar days prior to the
applicable record or effective date on which a Person would need to hold Common
Stock in order to participate in such transaction, and the Company will take all
steps reasonably necessary in order to insure that the Holder is given the
practical opportunity to exercise this Warrant prior to such time so as to
participate in such transaction; provided, however, that the failure to deliver
such notice or any defect therein shall not affect the validity of the
transaction required to be described in such notice.

         10.      Payment of Exercise Price. The Holder shall pay the Exercise
Price in immediately available funds.

         11.      Limitation on Exercise. Notwithstanding anything to the
contrary contained herein, the number of shares of Common Stock that may be
acquired by the Holder upon any exercise of this Warrant (or otherwise in
respect hereof) shall be limited to the extent necessary to insure that,
following such exercise (or other issuance), the total number of shares of
Common Stock then beneficially owned by such Holder and its Affiliates and any
other Persons whose beneficial ownership of Common Stock would be aggregated
with the Holder's for purposes of Section 13(d) of the Exchange Act, does not
exceed 4.999% (the "MAXIMUM PERCENTAGE") of the total number of issued and
outstanding shares of Common Stock (including for such purpose the shares of
Common Stock issuable upon such exercise). For such purposes, beneficial
ownership shall be determined in accordance with Section 13(d) of the Exchange
Act and the rules and regulations promulgated thereunder. Each delivery of an
Exercise Notice hereunder will constitute a representation by the Holder that it
has evaluated the limitation set forth in this paragraph and determined that
issuance of the full number of Warrant Shares requested in such Exercise Notice
is permitted under this paragraph. The Company's obligation to issue shares of
Common Stock in excess of the limitation referred to in this Section shall be
suspended (and shall not terminate or expire notwithstanding any contrary
provisions hereof) until such time, if any, as such shares of Common Stock may
be issued in compliance with such limitation. By written notice to the Company,
the Holder may waive the provisions of this Section or increase or decrease the
Maximum Percentage to any other percentage specified in such notice, but (i) any
such waiver or increase will not be effective until the 61st day after such
notice is delivered to the Company, and (ii) any such waiver or increase or
decrease will apply only to the Holder and not to any other holder of Warrants.

         12.      Fractional Shares. The Company shall not be required to issue
or cause to be issued fractional Warrant Shares on the exercise of this Warrant.
If any fraction of a Warrant

                                        7

<PAGE>

Share would, except for the provisions of this Section, be issuable upon
exercise of this Warrant, the number of Warrant Shares to be issued will be
rounded up to the nearest whole share.

         13.      Notices. Any and all notices or other communications or
deliveries hereunder (including without limitation any Exercise Notice) shall be
in writing and shall be deemed given and effective on the earliest of (i) the
date of transmission, if such notice or communication is delivered via facsimile
at the facsimile number specified in this Section prior to 6:30 p.m. (New York
City time) on a Trading Day, (ii) the next Trading Day after the date of
transmission, if such notice or communication is delivered via facsimile at the
facsimile number specified in this Section on a day that is not a Trading Day or
later than 6:30 p.m. (New York City time) on any Trading Day, (iii) the Trading
Day following the date of mailing, if sent by nationally recognized overnight
courier service, or (iv) upon actual receipt by the party to whom such notice is
required to be given. The address for such notices or communications shall be as
set forth in the Purchase Agreement.

         14.      Warrant Agent. The Company shall serve as warrant agent under
this Warrant. Upon 30 days' notice to the Holder, the Company may appoint a new
warrant agent. Any corporation into which the Company or any new warrant agent
may be merged or any corporation resulting from any consolidation to which the
Company or any new warrant agent shall be a party or any corporation to which
the Company or any new warrant agent transfers substantially all of its
corporate trust or stockholders services business shall be a successor warrant
agent under this Warrant without any further act. Any such successor warrant
agent shall promptly cause notice of its succession as warrant agent to be
mailed (by first class mail, postage prepaid) to the Holder at the Holder's last
address as shown on the Warrant Register.

         15.      Miscellaneous.

                  (a)      Subject to the restrictions on transfer set forth on
the first page hereof, this Warrant may be assigned by the Holder. This Warrant
may not be assigned by the Company except to a successor in the event of a
Fundamental Transaction. This Warrant shall be binding on and inure to the
benefit of the parties hereto and their respective successors and assigns.
Subject to the preceding sentence, nothing in this Warrant shall be construed to
give to any Person other than the Company and the Holder any legal or equitable
right, remedy or cause of action under this Warrant. This Warrant may be amended
only in writing signed by the Company and the Holder and their successors and
assigns.

                  (b)      The Company will not, by amendment of its governing
documents or through any reorganization, transfer of assets, consolidation,
merger, dissolution, issue or sale of securities or any other voluntary action,
avoid or seek to avoid the observance or performance of any of the terms of this
Warrant, but will at all times in good faith assist in the carrying out of all
such terms and in the taking of all such action as may be necessary or
appropriate in order to protect the rights of the Holder against impairment.
Without limiting the generality of the foregoing, the Company (i) will not
increase the par value of any Warrant Shares above the amount payable therefor
on such exercise, (ii) will take all such action as may be reasonably necessary
or appropriate in order that the Company may validly and legally issue fully
paid and nonassessable Warrant Shares on the exercise of this Warrant, and (iii)
will not close its

                                        8

<PAGE>

stockholder books or records in any manner which interferes with the timely
exercise of this Warrant.

                  (c)      GOVERNING LAW; VENUE; WAIVER OF JURY TRIAL. ALL
QUESTIONS CONCERNING THE CONSTRUCTION, VALIDITY, ENFORCEMENT AND INTERPRETATION
OF THIS WARRANT SHALL BE GOVERNED BY AND CONSTRUED AND ENFORCED IN ACCORDANCE
WITH THE LAWS OF THE STATE OF NEW YORK. EACH PARTY HEREBY IRREVOCABLY SUBMITS TO
THE EXCLUSIVE JURISDICTION OF THE STATE AND FEDERAL COURTS SITTING IN THE CITY
OF NEW YORK, BOROUGH OF MANHATTAN, FOR THE ADJUDICATION OF ANY DISPUTE HEREUNDER
OR IN CONNECTION HEREWITH OR WITH ANY TRANSACTION CONTEMPLATED HEREBY OR
DISCUSSED HEREIN (INCLUDING WITH RESPECT TO THE ENFORCEMENT OF ANY OF THE
TRANSACTION DOCUMENTS), AND HEREBY IRREVOCABLY WAIVES, AND AGREES NOT TO ASSERT
IN ANY SUIT, ACTION OR PROCEEDING, ANY CLAIM THAT IT IS NOT PERSONALLY SUBJECT
TO THE JURISDICTION OF ANY SUCH COURT, THAT SUCH SUIT, ACTION OR PROCEEDING IS
IMPROPER. EACH PARTY HEREBY IRREVOCABLY WAIVES PERSONAL SERVICE OF PROCESS AND
CONSENTS TO PROCESS BEING SERVED IN ANY SUCH SUIT, ACTION OR PROCEEDING BY
MAILING A COPY THEREOF VIA REGISTERED OR CERTIFIED MAIL OR OVERNIGHT DELIVERY
(WITH EVIDENCE OF DELIVERY) TO SUCH PARTY AT THE ADDRESS IN EFFECT FOR NOTICES
TO IT UNDER THIS AGREEMENT AND AGREES THAT SUCH SERVICE SHALL CONSTITUTE GOOD
AND SUFFICIENT SERVICE OF PROCESS AND NOTICE THEREOF. NOTHING CONTAINED HEREIN
SHALL BE DEEMED TO LIMIT IN ANY WAY ANY RIGHT TO SERVE PROCESS IN ANY MANNER
PERMITTED BY LAW. THE COMPANY HEREBY WAIVES ALL RIGHTS TO A TRIAL BY JURY.

                  (d)      The headings herein are for convenience only, do not
constitute a part of this Warrant and shall not be deemed to limit or affect any
of the provisions hereof.

                  (e)      In case any one or more of the provisions of this
Warrant shall be invalid or unenforceable in any respect, the validity and
enforceability of the remaining terms and provisions of this Warrant shall not
in any way be affected or impaired thereby and the parties will attempt in good
faith to agree upon a valid and enforceable provision which shall be a
commercially reasonable substitute therefor, and upon so agreeing, shall
incorporate such substitute provision in this Warrant.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK,
                             SIGNATURE PAGE FOLLOWS]

                                        9

<PAGE>

         IN WITNESS WHEREOF, the Company has caused this Warrant to be duly
executed by its authorized officer as of the date first indicated above.

                                            LYNX THERAPEUTICS, INC.

                                            By:_________________________________
                                            Name:_______________________________
                                            Title:______________________________

                                       10

<PAGE>

                             FORM OF EXERCISE NOTICE

(To be executed by the Holder to exercise the right to purchase shares of Common
Stock under the foregoing Warrant)

To: LYNX THERAPEUTICS, INC.

The undersigned is the Holder of Warrant No. _______ (the "WARRANT") issued by
Lynx Therapeutics, Inc., a Delaware corporation (the "COMPANY"). Capitalized
terms used herein and not otherwise defined have the respective meanings set
forth in the Warrant.

1.       The Warrant is currently exercisable to purchase a total of
         ______________ Warrant Shares.

2.       The undersigned Holder hereby exercises its right to purchase
         _________________ Warrant Shares pursuant to the Warrant.

3.       The holder shall pay the sum of $____________ to the Company in
         accordance with the terms of the Warrant.

4.       Pursuant to this exercise, the Company shall deliver to the holder
         _______________ Warrant Shares in accordance with the terms of the
         Warrant.

5.       Following this exercise, the Warrant shall be exercisable to purchase a
         total of ______________ Warrant Shares.

Dated:_____________________,___               Name of Holder:

                                              (Print)___________________________

                                              By:_______________________________
                                              Name:_____________________________
                                              Title:____________________________

                                              (Signature must conform in all
                                              respects to name of holder as
                                              specified on the face of the
                                              Warrant)

<PAGE>

                               FORM OF ASSIGNMENT

         [To be completed and signed only upon transfer of Warrant]

         FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers
unto ________________________________ the right represented by the within
Warrant to purchase ____________ shares of Common Stock of Lynx Therapeutics,
Inc. to which the within Warrant relates and appoints ________________ attorney
to transfer said right on the books of Lynx Therapeutics, Inc. with full power
of substitution in the premises.

Dated:______________________,___

                                             ___________________________________

                                             (Signature must conform in all
                                             respects to name of holder as
                                             specified on the face of the
                                             Warrant)

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                                             Address of Transferee

                                             ___________________________________

                                             ___________________________________

In the presence of:

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