Exhibit 10.23

                             UNCONDITIONAL GUARANTY

                                                               November 18, 1998

Chrysalis International Corporation
Chrysalis International Preclinical Services Corporation
Chrysalis DNX Transgenic Sciences Corporation
Chrysalis International Clinical Services Corporation
(Individually and collectively "Borrower")

Phoenix International Life Sciences Inc. ("Guarantor")

First Union National Bank ("Bank")
123 South Broad Street
Philadelphia, Pennsylvania 19109


To induce Bank to continue in financing arrangements with Borrower and to grant
forbearance to Borrower pursuant to that certain Forbearance Agreement of even
date herewith between Borrower and Bank (the "Forbearance Agreement), Guarantor
hereby absolutely, irrevocably and unconditionally guarantees to Bank and its
successors, assigns and affiliates the timely payment and performance of all
liabilities and obligations of Borrower to Bank and its affiliates, including,
but not limited to, all obligations under any notes, loan agreements, security
agreements, letters of credit, instruments, accounts receivable, contracts,
drafts, leases, chattel paper, indemnities, acceptances, repurchase agreements,
overdrafts, and the Loan Documents defined below, however and whenever incurred
or evidenced, whether primary, secondary, direct, indirect, absolute,
contingent, due or to become due, now existing or hereafter contracted or
acquired, and all modifications, extensions or renewals thereof, including
without limitation all principal, interest, charges, and costs and expenses
incurred thereunder (including attorneys' fees and other costs of collection
incurred, regardless of whether suit is commenced) (collectively, the
"Guaranteed Obligations").

Guarantor further covenants and agrees:

GUARANTOR'S LIABILITY. This Guaranty is a continuing and unconditional guaranty
of payment and performance and not of collection. The parties to this Guaranty
are jointly and severally obligated hereunder. This Guaranty does not impose any
obligation on Bank to extend or continue to extend credit or otherwise deal with
Borrower at any subsequent time. This Guaranty shall continue to be effective or
be reinstated, as the case may be, if at any time any payment of the Guaranteed
Obligations is rescinded, avoided or for any other reason must be returned by
Bank, and the returned payment shall remain payable as part of the Guaranteed
Obligations, all as though such payment had not been made. Except to the extent
the provisions of this Guaranty give the Bank additional rights, this Guaranty
shall not be deemed to supersede or replace any other guaranties given to Bank
by Guarantor; and the obligations guaranteed hereby shall be in addition to any
other obligations guaranteed by Guarantor pursuant to any other agreement of
guaranty given to Bank and other guaranties of the Guaranteed Obligations.

TERMINATION OF GUARANTY. Guarantor may terminate this Guaranty by written
notice, delivered personally to or received by certified or registered United
States Mail by an authorized officer of the Bank at the address for notices
provided herein. Such termination shall be effective with respect to Guaranteed
Obligations arising more than 15 days after the date such written notice is
received by said Bank officer. Guarantor may not terminate this Guaranty as to
Guaranteed Obligations (including any subsequent extensions, modifications or
compromises of the Guaranteed Obligations) 





then existing. Termination of this Guaranty by any single Guarantor will not
affect the existing and continuing obligations of any other guarantor hereunder.

APPLICATION OF PAYMENTS. Monies received from any source by Bank for application
toward payment of the Guaranteed Obligations may be applied to such Guaranteed
Obligations in any manner or order deemed appropriate by Bank.

CONSENT TO MODIFICATIONS. Guarantor CONSENTS AND AGREES THAT BANK MAY FROM TIME
TO TIME, IN ITS SOLE DISCRETION, WITHOUT AFFECTING, IMPAIRING, LESSENING OR
RELEASING THE OBLIGATIONS OF THE GUARANTOR HEREUNDER: permit any change in the
business or other dealings and relations of Borrower or any other guarantor with
Bank, all in such manner and upon such terms as Bank may deem appropriate, and
without notice to or further consent from Guarantor. No invalidity,
irregularity, discharge or unenforceability of, or action or omission by Bank
relating to any part of, the Guaranteed Obligations or any security therefor
shall affect or impair this Guaranty.

WAIVERS AND ACKNOWLEDGMENTS. Guarantor WAIVES AND RELEASES THE FOLLOWING RIGHTS,
DEMANDS, AND DEFENSES Guarantor may have with respect to Bank and collection of
the Guaranteed Obligations: (a) promptness and diligence in collection of any of
the Guaranteed Obligations from Borrower or any other person liable thereon, and
in foreclosure of any security interest and sale of any property serving as
collateral for the Guaranteed Obligations; (b) any law or statute that requires
that Bank make demand upon, assert claims against, or collect from Borrower or
other persons or entities, foreclose any security interest, sell collateral,
exhaust any remedies, or take any other action against Borrower or other persons
or entities prior to making demand upon, collecting from or taking action
against Guarantor with respect to the Guaranteed Obligations; (c) any law or
statute that requires that Borrower or any other person be joined in, notified
of or made part of any action against Guarantor; (d) that Bank preserve insure
or perfect any security interest in collateral or sell or dispose of collateral
in a particular manner or at a particular time; (e) notice of any new
transactions or other relationships between Bank, Borrower and/or any guarantor,
and of changes in the financial condition of, ownership of, or business
structure of Borrower or any other guarantor; (f) presentment, protest, notice
of dishonor, notice of default, demand for payment, notice of intention to
accelerate maturity, notice of acceleration of maturity, notice of sale, and all
other notices of any kind whatsoever; (g) the right to assert against Bank any
defense (legal or equitable), set-off, counterclaim, or claim that Guarantor may
have at any time against Borrower or any other party liable to Bank; (h) all
defenses relating to invalidity, insufficiency, unenforceability, enforcement,
release or impairment of Bank's lien on any collateral, of the Loan Documents,
or of any other guaranties held by Bank; (i) any claim or defense that
acceleration of maturity of the Guaranteed Obligations is stayed against
Guarantor because of the stay of assertion or of acceleration of claims against
any other person or entity for any reason including the bankruptcy or insolvency
of that person or entity; and (j) the benefit of any exemption claimed by
Guarantor. Guarantor acknowledges and represents that it has relied upon its own
due diligence in making its own independent appraisal of Borrower, Borrower's
business affairs and financial condition, and any collateral; Guarantor will
continue to be responsible for making its own independent appraisal of such
matters; and Guarantor has not relied upon and will not hereafter rely upon Bank
for information regarding Borrower or any collateral.

FINANCIAL CONDITION. Guarantor warrants, represents and covenants to Bank that
on and after the date hereof: (a) the fair saleable value of Guarantor's assets
exceeds its liabilities, Guarantor is meeting its current liabilities as they
mature, and Guarantor is and shall remain solvent; (b) all financial statements
of Guarantor furnished to Bank are correct and accurately reflect the financial
condition of Guarantor as of the respective dates thereof; (c) since the date of
such financial statements, there has not occurred a material adverse change in
the financial condition of Guarantor; (d) there are not now pending any court or
administrative proceedings or undischarged judgments against Guarantor, no
federal or state tax liens have been filed or threatened against Guarantor, and
Guarantor is not in default or claimed default under any agreement; and (e) at
such 




reasonable times as Bank requests, Guarantor will furnish Bank with such
financial information as Guarantor makes available to its shareholders,
generally.

INTEREST. Regardless of any other provision of this Guaranty or other Loan
Documents, if for any reason the effective interest on any of the Guaranteed
Obligations should exceed the maximum lawful interest, the effective interest
shall be deemed reduced to and shall be such maximum lawful interest, and any
sums of interest which have been collected in excess of such maximum lawful
interest shall be applied as a credit against the unpaid principal balance of
the Guaranteed Obligations.

DEFAULT. If any of the following events occur, a default ("Default") under this
Guaranty shall exist: (a) Failure of timely payment or performance of the
Guaranteed Obligations or a default under any Loan Document; (b) A breach of any
agreement or representation contained or referred to in the Guaranty, or any of
the Loan Documents, or contained in any other contract or agreement of Guarantor
with Bank or its affiliates, whether now existing or hereafter arising; (c) The
death of, appointment of a guardian for, dissolution of, termination of
existence of, loss of good standing status by, appointment of a receiver for,
assignment for the benefit of creditors of, or the commencement of any
insolvency or bankruptcy proceeding by or against, Guarantor or any general
partner of or the holder(s) of the majority ownership interests of Guarantor;
(d) the occurrence of a Terminating Event under the Forbearance Agreement;
and/or (e) The entry of any monetary judgment or the assessment against, the
filing of any tax lien against, or the issuance of any writ of garnishment or
attachment against any property of or debts due Guarantor.

If a Default occurs, the Guaranteed Obligations shall be due immediately and
payable without notice. Guarantor shall pay interest on the Guaranteed
Obligations from such Default at the highest rate of interest charged on any of
the Guaranteed Obligations, subject to the Pledge Agreement.

ATTORNEY'S FEES AND OTHER COSTS OF COLLECTION. Guarantor shall pay all of Bank's
reasonable expenses incurred to enforce or collect any of the Guaranteed
Obligations, including, without limitation, reasonable arbitration, paralegals',
attorneys' and experts' fees and expenses, whether incurred without the
commencement of a suit, in any suit, arbitration, or administrative proceeding,
or in any appellate or bankruptcy proceeding.

MISCELLANEOUS. (a) ASSIGNMENT. This Guaranty and other Loan Documents shall
inure to the benefit of and be binding upon the parties and their respective
heirs, legal representatives, successors and assigns. Bank shall not, without
the prior written consent of Guarantor, assign this Guaranty, the Pledge and
Assignment and Agreement, or Bank's interest in the Loan Documents, or any
collateral securing the Loan Documents. (b) APPLICABLE LAW; CONFLICT BETWEEN
DOCUMENTS. This Guaranty and other Loan Documents shall be governed by and
construed under the laws of the state named in Bank's address shown above
without regard to that state's conflict of laws principles. If the terms of this
Guaranty should conflict with the terms of any commitment letter that survives
closing, the terms of this Guaranty shall control. (c) JURISDICTION. Guarantor
irrevocably agrees to non-exclusive personal jurisdiction in the state named in
Bank's address shown above. (d) SEVERABILITY. If any provision of this Guaranty
or of the other Loan Documents shall be prohibited or invalid under applicable
law, such provision shall be ineffective but only to the extent of such
prohibition or invalidity, without invalidating the remainder of such provision
or the remaining provisions of this Guaranty or other document. (e) NOTICES. Any
notices to Guarantor shall be sufficiently given, if in writing and mailed or
delivered to the Guarantor's address shown above or such other address as
provided hereunder, and to Bank, if in writing and mailed or delivered to Bank's
office address shown above or such other address as Bank may specify in writing
from time to time. In the event that Guarantor changes Guarantor's address at
any time prior to the date the Guaranteed Obligations are paid in full,
Guarantor agrees to promptly give written notice of said change of address by
registered or certified mail, return receipt requested, all charges prepaid. (f)
PLURAL; CAPTIONS. All references in the Loan Documents to borrower, guarantor,





person, document or other nouns of reference mean both the singular and plural
form, as the case may be, and the term "person" shall mean any individual,
person or entity. The captions contained in the Loan Documents are inserted for
convenience only and shall not affect the meaning or interpretation of the Loan
Documents. (g) BINDING CONTRACT. Guarantor by execution of and Bank by
acceptance of this Guaranty agree that each party is bound to all terms and
provisions of this Guaranty. (h) AMENDMENTS, WAIVERS AND REMEDIES. No waivers,
amendments or modifications of this Guaranty and other Loan Documents shall be
valid unless in writing and signed by an officer of Bank and Guarantor. No
waiver by Bank of any Default shall operate as a waiver of any other Default or
the same Default on a future occasion. Neither the failure nor any delay on the
part of Bank in exercising any right, power, or privilege granted pursuant to
this Guaranty and other Loan Documents shall operate as a waiver thereof, nor
shall a single or partial exercise thereof preclude any other or further
exercise or the exercise of any other right, power or privilege. All remedies
available to Bank with respect to this Guaranty and other Loan Documents and
remedies available at law or in equity shall be cumulative and may be pursued
concurrently or successively. (i) PARTNERSHIPS. If Guarantor is a partnership,
the obligations, liabilities and agreements on the part of Guarantor shall
remain in full force and effect an fully applicable notwithstanding any changes
in the individuals comprising the partnership. The term "Guarantor" includes any
altered or successive partnerships, and predecessor partnership(s) and the
partners shall not be released from any obligations or liabilities hereunder.
(j) LOAN DOCUMENTS. The term "Loan Documents" refers to all documents executed
by Borrower in favor of Bank including, but not limited to, documents identified
in the Forbearance Agreement, and includes the Forbearance Agreement

SECURITY; NO RECOURSE. Guarantor has granted Bank a security interest in the
collateral (the "Collateral") described in that certain Pledge and Assignment
Agreement of even date herewith (the "Pledge Agreement"). Notwithstanding
anything to the contrary set forth herein, Bank's recourse against Guarantor
upon the occurrence of a Default shall be limited to the Collateral and Bank's
other remedies set forth in the Pledge Agreement. Guarantor shall not be
responsible for the value of the Collateral afte its pledge to Bank. Bank shall
not assert or commence any legal or equitable proceeding before any court,
agency or other body against Guarantor on account of this Guaranty. Guarantor
shall have no liability to Bank under this Guaranty, except to the extent of
Guarantor's interest in the Collateral. Notwithstanding Bank's agreement to
limit recourse against the Guarantor to the Collateral, in the event Guarantor
disputes its liabilities and obligations under this Guaranty and/or the Pledge
Agreement, and/or opposes any application of the Collateral to the Guaranty
Obligations, in the event Bank prevails in any such dispute, Guarantor
acknowledges and agrees that Guarantor shall be liable to Bank for repayment of
Bank's reasonable fees and expenses (including attorneys' fees and
disbursements) incurred in connection with any such dispute or opposition, and
the obligation in respect of such expenses shall be a full recourse obligation
of Guarantor.

ARBITRATION. Upon demand of any party hereto, whether made before or after
institution of any judicial proceeding, any claim or controversy arising out of
or relating to the Loan Documents between parties hereto (a "Dispute") shall be
resolved by binding arbitration conducted under and governed by the Commercial
Financial Disputes Arbitration Rules (the "Arbitration Rules") of the American
Arbitration Association (the "AAA") and the Federal Arbitration Act. Disputes
may include, without limitation, tort claims, counterclaims, a dispute as to
whether a matter is subject to arbitration, claims brought as class actions, or
claims arising from documents executed in the future. A judgment upon the award
may be entered in any court having jurisdiction. Notwithstanding the foregoing,
this arbitration provision does not apply to disputes under or related to swap
agreements.

SPECIAL RULES. All arbitration hearings shall be conducted in the city named in
the address of Bank first stated above. A hearing shall begin within 90 days of
demand for arbitration and all hearings shall conclude within 120 days of demand
for arbitration. These time limitations may not be extended unless a party shows
cause for extension and then for no more than a total of 60 




days. The expedited procedures set forth in Rule 51 ET SEQ. of the Arbitration
Rules shall be applicable to claims of less than $1,000,000.00.
Arbitrators shall be licensed attorneys selected from the Commercial Financial
Dispute Arbitration Panel of the AAA. The parties do not waive applicable
Federal or state substantive law except as provided herein.

PRESERVATION AND LIMITATION OF REMEDIES. Notwithstanding the preceding binding
arbitration provisions, the parties agree to preserve, without diminution,
certain remedies that any party may exercise before or after an arbitration
proceeding is brought. The parties shall have the right to proceed in any court
of proper jurisdiction or by self-help to exercise or prosecute the following
remedies, as applicable: (i) all rights to foreclose against any real or
personal property or other security by exercising a power of sale or under
applicable law by judicial foreclosure including a proceeding to confirm the
sale; (ii) all rights of self-help including peaceful occupation of real
property and collection of rents, set-off, and peaceful possession of personal
property; (iii) obtaining provisional or ancillary remedies including injunctive
relief, sequestration, garnishment, attachment, appointment of receiver and
filing an involuntary bankruptcy proceeding; and (iv) when applicable, a
judgment by confession of judgment. Any claim or controversy with regard to any
party's entitlement to such remedies is a Dispute.

The parties agree that they shall not have a remedy of punitive or exemplary
damages against other parties in any Dispute and hereby waive any right or claim
to punitive or exemplary damages they have now or which may arise in the future
in connection with any Dispute whether the Dispute is resolved by arbitration or
judicially.

WAIVER OF JURY TRIAL. THE PARTIES ACKNOWLEDGE THAT BY AGREEING TO BINDING
ARBITRATION THEY HAVE IRREVOCABLY WAIVED ANY RIGHT THEY MAY HAVE TO JURY TRIAL
WITH REGARD TO A DISPUTE.

IN WITNESS WHEREOF, Guarantor, on the day and year first written above, has
caused this Unconditional Guaranty to be executed under seal.

                    PHOENIX INTERNATIONAL LIFE SCIENCES INC.


CORPORATE                 By:           /s/ Jean-Yves Caloz
SEAL                         ---------------------------------------------------
                       Name:  Jean-Yves Caloz
                       Title: Senior Vice President and Secretary