Document:

<PAGE>

                                                                    EXHIBIT 10.4

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), OR THE SECURITIES
LAWS OF ANY STATE.  THE SECURITIES MAY NOT BE TRANSFERRED EXCEPT PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES
LAWS OR PURSUANT TO AN APPLICABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS
OF SUCH ACT AND SUCH LAWS OR PURSUANT TO A WRITTEN OPINION OF COUNSEL (WHICH
COUNSEL AND OPINION SHALL BE REASONABLY SATISFACTORY TO THE COMPANY) THAT SUCH
REGISTRATION IS NOT REQUIRED.

                         CALL AND PUT OPTION AGREEMENT
                         -----------------------------

     CALL AND PUT OPTION AGREEMENT (the "Option Agreement"), dated as of
December 4, 2001, by and between Laidlaw Global Corporation, a Delaware
corporation (the "Optionor"), and Third Security, LLC, a Virginia limited
liability company (the "Option Holder").

     WHEREAS, the Option Holder and the Optionor are negotiating to enter into a
Stock Purchase Agreement (the "Purchase Agreement") whereby the Option Holder
will purchase and the Optionor will sell shares of common stock that in the
aggregate equal $5,000,000, so that the fully diluted (taking into account all
outstanding warrants, options and convertible securities) equity ownership of
the Option Holder would represent 45% of the common shares of the Optionor.  The
Option Holder will have the option, in its sole discretion, to purchase
additional new common shares of the Optionor at the same per share purchase
price so that the fully diluted (taking into account all outstanding warrants,
options and convertible securities) equity ownership of the Option Holder would
represent up to 51% of the common shares of the Optionor.  The final percentage
of ownership within the 45% and 51% range will be within the sole discretion of
the Option Holder and will be set forth in the Purchase Agreement;

     WHEREAS, concurrent herewith, the Option Holder is loaning (the "Loan"),
the Optionor $1,500,000 pursuant to that certain Secured Convertible Note (the
"Convertible Note");

     WHEREAS, as part of the total investment contemplated by the parties hereto
and as partial consideration for the Loan, the Optionor grants to the Option
Holder an option to purchase from the Optionor, subject to the terms and
conditions set forth herein, $1,000,000 of the shares of Common Stock, par value
$.0001 per share ("Common Stock") of the Optionor at a purchase price set forth
below;

     WHEREAS,  concurrent with the execution hereof, the Option Holder intends
to partially exercise the Call Option (as defined below) for approximately
$300,000 of the shares of Common Stock of the Optionor; and

     WHEREAS, as part of the total investment contemplated by the parties hereto
and as partial consideration for the Loan, the Optionor grants to the Option
Holder the Put Option (as defined below), subject to the terms and conditions
set forth herein, all of the shares of Common Stock of the Optionor owned by the
Option Holder as of the date of such exercise of the Put
<PAGE>

Option, whether acquired pursuant to the Call Option, upon conversion of the
Convertible Note or otherwise (the "Put Option Shares").

     ACCORDINGLY, THE PARTIES AGREE AS FOLLOWS:

     1.   Grant of Call Option; Grant of Put Option.
          -----------------------------------------

          1.1.  Grant of Call Option: Exercise Price.  Subject to the terms
                ------------------------------------
and conditions set forth herein, the Optionor grants to the Option Holder an
exclusive and irrevocable option (the "Call Option") to purchase from the
Optionor, in whole or in part, up to $1,000,000 of shares of Common Stock (the
"Call Option Shares"), at a purchase price per share (the "Call Exercise Price")
equal to $0.1972. The number of Call Option Shares shall be subject to
adjustment as provided in Section 2.

          1.2.  Duration of Call Option.  This Call Option may be exercised in
                -----------------------
whole or in part at any time or from time to time after the date hereof and on
or prior to December 17, 2001 (the "Call Option Termination Date").

          1.3.  Grant of Put Option.  Subject to the terms and conditions set
                -------------------
forth herein, the Optionor grants to the Option Holder an exclusive and
irrevocable option (the "Put Option," and together with the Call Option, the
"Options") to sell to the Optionor, in whole or in part, any and all of its Put
Option Shares at the same price that the Option Holder paid for such shares
(the "Put Exercise Price").

          1.4. Duration of Put Option.  This Put Option may be exercised in
               ----------------------
whole or in part at any time or from time to time after the date hereof and
prior to the earlier of (i) the closing of the transactions contemplated by the
Purchase Agreement and (ii) the Maturity Date (as defined in the Note) (the "Put
Option Termination Date"), in the sole and absolute discretion of the Option
Holder.

          1.5. Manner of Exercising the Options.
               --------------------------------
               (a) The Call Option or the Put Option, as the case may be, shall
be exercisable by the Option Holder or any permitted assigns by surrender of a
completed and fully executed Option Exercise Notice (in the form attached hereto
as Exhibit A hereto in the case of the Call Option or Exhibit B in the case of
   ---------                                          ---------
the Put Option, in either case, the "Option Exercise Notice") to the Optionor,
not less than one business day prior to the date specified in such Option
Exercise Notice for the closing of the purchase and sale of the Call Option
Shares or the Put Option Shares with respect to such Option Exercise Notice (the
"Option Closing Date") pursuant to either the Call Option or the Put Option, as
the case may be.

               (b) In the case of the exercise of the Call Option, on the Option
Closing Date, the Option Holder shall deliver to the Optionor by wire transfer
of immediately available funds, the aggregate Call Exercise Price for the Call
Option Shares so acquired, against delivery by the Optionor to the Option Holder
of a stock certificate in proper form to transfer to the Option Holder the Call
Option Shares so acquired.

                                      -2-
<PAGE>

               (c) In the case of the exercise of the Put Option, on the Option
Closing Date, the original principal balance of the Convertible Note shall
automatically and without any needed action on the part of the Optionor or the
Option Holder increase by an amount equal to the aggregate Put Exercise Price
for the Put Option Shares so reacquired, against delivery by the Option Holder
to the Optionor of a duly executed assignment in proper form to transfer the Put
Option Shares back to the Optionor.

     2.   Adjustment of Call Option Shares; Substitute Shares.
          ---------------------------------------------------

          2.1. Changes in Capital Structure.  The number and type of Call
               ----------------------------
Option Shares transferable by the Optionor upon exercise of the Call Option by
the Option Holder shall be equitably adjusted in the event of any stock split,
combination, stock dividend payable in shares of stock or recapitalization, or
conversion or exchange for other securities or property as a result of a merger,
sale, liquidation or reorganization of the Optionor or the issue of any
Distribution or Distribution Securities (as defined in Section 2.2), or other
similar change in capital structure of the Optionor or as a result of any other
disposition or conversion of the Call Option Shares or the proceeds therefrom
(including, without limitation, any Distribution or Distribution Securities).

          2.2. Distribution Securities.  If any Distribution (as hereinafter
               -----------------------
defined) of securities or other property issued in connection with a transaction
contemplated by Section 2.1 ("Distribution Securities") with respect to the Call
Option Shares is due, the cash, certificates or other instruments evidencing
title to such Distribution or Distribution Securities, together with appropriate
instruments of transfer shall be delivered to the Option Holder upon exercise of
the Call Option. Any Distribution or Distribution Securities shall become a part
of the Call Option Shares to which it relates, and upon the exercise of the Call
Option shall be transferred to the Option Holder without extra cost. A
"Distribution" means any property receivable by the Optionor as owner of any
Call Option Shares, or as owner of any Distribution or Distribution Securities,
and shall include, without limitation, non-cash dividends, cash, securities or
other property arising from a reorganization, recapitalization, stock split,
liquidation, sale or merger of the Optionor or the issuer of any security which
is a Distribution or Distribution Security, or otherwise.

          2.3. Below Call Exercise Price Issuances.  If at any time while all
               -----------------------------------
or any portion of the Call Option remains outstanding, all or any portion of the
Call Option shall be exercised subsequent to (a) any sale of shares of Common
Stock at a price per share less than the Call Option Exercise Price then
applicable, or (b) any issuance of any security convertible into shares of
Common Stock with a conversion price per share less than the Call Option
Exercise Price then applicable, then in any and every such event, the Call
Option Exercise Price shall be reduced and shall be equal to such lower sales or
conversion price.

          2.4. Purchase Price Adjustment.  In the event that the purchase
               -------------------------
price of the shares of the Optionor Common Stock to be agreed upon in the
Purchase Agreement (the "Purchase Price") is lower than the Call Exercise Price
set forth herein, the number of Call Option Shares shall be increased
proportionally such that the Call Exercise Price would have equaled such
Purchase Price as of the Option Closing Date. The Optionor shall immediately
issue such additional shares of Common Stock to the Option Holder.

                                      -3-
<PAGE>

     3.   Representations, Warranties and Covenants of the Optionor.
          ---------------------------------------------------------

          3.1. Organization and Powers.  The Optionor and each of its material
               -----------------------
subsidiaries are corporations duly incorporated, validly existing and in good
standing under the laws of their states of incorporation, with all requisite
corporate power and authority to carry on the business in which they are engaged
and to own the properties they own, and the Optionor has all requisite power and
authority to execute and deliver this Option Agreement and to consummate the
transactions contemplated hereby.  The Optionor and each of its material
subsidiaries are duly qualified and licensed to do business and are in good
standing in all jurisdictions where the nature of their business makes such
qualification necessary, except where the failure to be qualified or licensed
would not have a material adverse effect on the business of the Optionor and its
material subsidiaries, taken as a whole.

          3.2. Litigation.  There are no legal actions or administrative or
               ----------
arbitration proceedings or investigations instituted, or to the best knowledge
of the Optionor threatened, against the Optionor, that could reasonably be
expected to have a material adverse effect on the business of the Optionor and
its subsidiaries taken as a whole, or which concerns the transactions
contemplated by this Option Agreement.

          3.3. SEC Documents.  The Optionor's audited consolidated financial
               -------------
statements as of December 31, 2000, contained in its Annual Report on Form 10-K
for the year ended December 31, 2000 (the "Form 10-K"), including the notes
contained therein, fairly present the consolidated financial position of the
Optionor at the respective dates thereof and the results of its consolidated
operations for the periods purported to be covered thereby. Such financial
statements have been prepared in conformity with generally accepted accounting
principles consistently applied with prior periods subject to any comments and
notes contained therein. All liabilities, contingent and other, of the Optionor
and its subsidiaries, are set forth in the financial statements as of September
30, 2001 contained in its Quarterly Report on Form 10-Q for the nine months
ended September 30, 2001 (the "Form 10-Q"), excepting only liabilities incurred
in the ordinary course of business subsequent to December 31, 2000, and
liabilities of the type not required under generally accepted accounting
principles to be reflected in such financial statements. Since September 30,
2001, there has been no material adverse change in the financial condition of
the Optionor from the financial condition stated in such financial statements.
Prior to the issuance of shares contemplated by this Option Agreement, the
Optionor has 26,641,580 shares of Common Stock outstanding and 30,988,342 shares
of Common Stock outstanding on a fully diluted basis (taking into account all
outstanding warrants, options and convertible securities). All of such
outstanding shares of capital stock have been, or upon issuance will be, validly
issued, fully paid and non-assessable. No shares of capital stock of the
Optionor are subject to preemptive rights or any other similar rights of the
stockholders of the Optionor. Except as disclosed in the Form 10-K or Form 10-Q,
(i) the Optionor has no indebtedness for borrowed money and no agreement
providing for indebtedness for borrowed money, (ii) the Optionor has no share
purchase agreements, rights plans or agreements containing similar provisions
and no agreements containing anti-dilution provisions, and (iii) no anti-
dilution provisions which have, individually or in the aggregate, any dilutive
effect on the Option Holder's investment are triggered as a result of any of the
transactions contemplated hereby.

                                      -4-
<PAGE>

          3.4. No Brokers. The Optionor has not employed any broker, agent,
               ----------
finder or investment banker in connection with any transaction contemplated by
this Option Agreement.

          3.5. Authorization.  The Optionor, by appropriate and required
               -------------
corporate action, has (i) duly authorized the execution of this Option Agreement
and the issuance and delivery of the Call Option Shares and (ii) reserved for
issuance sufficient shares of Common Stock as may be necessary from time to time
to be issued upon exercise of the Call Option. The Call Option Shares are not
subject to preemptive or other rights of any stockholders of the Optionor and
when issued in accordance with the terms of this Option Agreement and the
Certificate of Incorporation of the Optionor, the Call Option Shares will be
validly issued, fully paid and nonassessable and free and clear of all pledges,
liens and encumbrances.

          3.6. No Conflicts.  Performance of this Option Agreement and
               ------------
compliance with the provisions hereof will not violate any provision of any
applicable law or of the Certificate of Incorporation or Bylaws of the Optionor,
or of any of its subsidiaries, and, will not conflict with or result in any
breach of any of the terms, conditions or provisions of, or constitute a default
under, or result in the creation or imposition of any lien, charge or
encumbrance upon, any of the properties or assets of the Optionor, or of any of
its subsidiaries, pursuant to the terms of any indenture, mortgage, deed of
trust or other agreement or instrument binding upon the Optionor, or any of its
subsidiaries, other than such breaches, defaults or liens which would not have a
material adverse effect on the Optionor and its subsidiaries taken as a whole.

          3.7. Full Disclosure.  The Form 10-K, the Form 10-Q and the other
               ---------------
documents (the "Disclosure Documents"), filed by the Optionor subsequent to
December 31, 2000, with the Securities and Exchange Commission (the "SEC")
pursuant to the Securities Exchange Act of 1934, as amended (the "Exchange
Act"), taken together, do not contain any untrue statement of a material fact or
omit to state a material fact required to be stated therein to make the
statements contained therein not misleading. No representation or warranty made,
nor any document, statement, or financial statement prepared or furnished by the
Optionor in connection herewith, taken together, contains any untrue statement
of material fact, or omits to state a material fact necessary to make the
statements or facts contained herein or therein not misleading.

          3.8. Validity and Binding Nature.  This Option Agreement, has been
               ---------------------------
duly executed and delivered by the Optionor and constitutes a legal, valid and
binding obligation of the Optionor, enforceable against the Optionor in
accordance with its terms.

          3.9.  Consents.  No registration, authorization, approval,
                --------
qualification or consent of any court or governmental authority or agency is
necessary in connection with the execution and delivery and performance of this
Option Agreement or the offering, issuance or sale of the Call Option Shares
under this Option Agreement.

          3.10. Timely Filings.  The Optionor has timely filed with the SEC all
                --------------
documents required to be filed by the Optionor under the Exchange Act.

          3.11. Investment Company.  The Optionor is not now, and after the
                ------------------
sale of the Call Option Shares under this Option Agreement and the application
of the net proceeds from the

                                      -5-
<PAGE>

sale of the Call Option Shares will not be, an "investment company" within the
meaning of the Investment Company Act of 1940, as amended.

          3.12. No Registration.  Subject to the accuracy of the Option Holder's
                ---------------
representations and warranties in Section 4 of this Agreement, the offer, sale,
and issuance of the Call Option Shares in conformity with the terms of this
Option Agreement constitute transactions exempt from the registration
requirements of Section 5 of the Securities Act and from the registration or
qualification requirements of the laws of any applicable state or United States
jurisdiction.

          3.13. No Offers.  Neither the Optionor, nor any of its affiliates,
                ---------
nor any person acting on its or their behalf, has directly or indirectly made
any offers or sales in any security or solicited any offers to buy any security
under circumstances that would require registration under the Securities Act of
the issuance of the Call Option Shares to the Option Holder. The issuance of the
Call Option Shares to the Option Holder will not be integrated with any other
issuance of the Optionor's securities (past, current or future) for purposes of
the Securities Act or any applicable rules of the American Stock Exchange. The
Optionor will not make any offers or sales of any security (other than the Call
Option Shares) that would cause the offering of the Call Option Shares to be
integrated with any other offering of securities by the Optionor for purposes of
any registration requirement under the Securities Act or any applicable rules of
the American Stock Exchange.

          3.14. Compliance with Laws.  The business and operations of the
                --------------------
Optionor and its subsidiaries have been and are being conducted in compliance
with all applicable state and local laws, ordinances, rules, regulations and
orders except those laws, ordinances, rules, regulations and orders the failure
with which to comply would not, in the aggregate, have a material adverse
effect.

          3.15. Tax Returns and Audits. The Optionor and its subsidiaries
                ----------------------
have duly filed all income, franchise and other federal, state and local tax
returns, notices and reports which they individually or collectively have been
or are required to file except where the failure to file such returns would not
have a material adverse effect. The provisions for federal, state and local
taxes reflected in the financial statements included in the Disclosure
Documents, as they relate to the Optionor, are adequate to cover the liabilities
of the Optionor for such taxes with respect to the periods then ended and for
all prior periods.

          3.16. Employee Benefit Plans.
                ----------------------

                (a)  All Employee Plans and their related trusts have been and
are maintained in material compliance with applicable requirements of the
Employee Retirement Income Security Act of 1974, as amended ("ERISA"), the
Internal Revenue Code of 1986, as amended (the "Code") and all other federal and
state statutes and regulations relating to employee benefit plans. "Employee
Plans" shall be defined to include all employee welfare benefit plans (as
defined in Section 3(1) of ERISA), employee pension benefit plans (as defined in
Section 3(2) of ERISA) and all bonus, stock option, stock purchase, benefit,
profit sharing, savings, vacation, retirement, disability, insurance, incentive,
deferred compensation and other similar fringe or employee benefit plans,
programs or arrangements for the benefit of, or relating

                                      -6-
<PAGE>

to, any employee of the Optionor or its subsidiaries which the Optionor or its
subsidiaries contribute to or maintain.

                (b)  Except as provided in the Disclosure Documents, neither
the Optionor nor any of its subsidiaries has any material liability with respect
to any "employee benefit plan," as defined in Section 3(3) of ERISA, currently
or formerly maintained by the Company.

          3.17. Further Assurances.  Upon the reasonable request of the Option
                ------------------
Holder, the Optionor will prepare, execute and deliver any further instruments
and do any further acts that may be necessary to carry out more effectively the
purpose of this Option Agreement.

     4.   Representations and Covenants of the Option Holder.
          --------------------------------------------------

          4.1.  Investment Representations.
                --------------------------

                (a) The Call Option Shares are being acquired (i) for the Option
Holder's own account, not for the account of any other person and (ii) for
investment and not with a view to distribution or resale except in compliance
with applicable laws regulating securities;

                (b) The Option Holder is capable of evaluating the merits and
risks of its investment in the securities;

                (c) The Option Holder understands and acknowledges that an
investment in the Optionor as represented by the Call Option Shares is
speculative in nature and is subject to a risk of loss in whole or in part; and

                (d) The Option Holder understands and acknowledges that it must
bear the economic risk of investment for an indefinite period of time because
the transfer to the Option Holder of the Call Option Shares and the Distribution
and Distribution Securities has not been registered under the Securities Act,
and the Call Option Shares and the Distributions and Distribution Securities
cannot be transferred by the Option Holder unless such transfer is registered
under the Securities Act or registration is not required in connection with such
transfer.

     5.   Miscellaneous.
          -------------

          5.1.  Amendment.  This Agreement may only be amended by a writing
                ---------
signed by the Optionor and the Option Holder.

          5.2.  Assignment.
                ----------
                (a)  The Optionor may not assign this Option Agreement or any
of the Call Option Shares, Distributions or Distribution Securities without the
prior written consent of the Option Holder. Any attempt to assign this Option
Agreement, any interest therein or any such Call Option Shares, Distributions or
Distribution Securities and any levy of execution, attachment, or similar
process on such securities or property shall be null and void. Subject to the

                                      -7-
<PAGE>

foregoing, this Option Agreement shall be binding on and inure to the benefit of
the successors and assigns of the Optionor.

                (b)  The Option Holder may not assign any of its right, title
and interest in this Option Agreement other than to an affiliate of the Option
Holder without the prior consent of the Optionor, which shall not be
unreasonably withheld. Following any permitted assignment, this Option Agreement
shall be binding upon and inure to the benefit of any successor and assign. Such
assignment shall be conditioned on compliance with any applicable state and
federal securities laws and, upon request by the Optionor, the Option Holder
shall furnish an opinion of counsel to such effect, reasonably satisfactory to
the Optionor.

          5.3.  Entire Agreement; Controlling Document.  This Option Agreement
                --------------------------------------
constitutes the entire agreement of the parties with respect to the subject
matter hereof and supersedes any and all prior negotiations, correspondence and
understandings between the parties with respect to the subject matter hereof,
whether oral or in writing.

          5.4.  Notices.  All notices and other communications under this
                -------
Option Agreement shall be in writing, shall be effective when received, and
shall in any event be deemed to have been received on the date of delivery if
delivered personally or by telecopier; on the second business day after the
business day of deposit with the U.S. Postal Service for delivery by first class
mail, registered or certified, postage prepaid; or on the first business day
after the business day of deposit with a courier for overnight delivery, freight
prepaid; in each such case, addressed as follows (until any such address is
changed by notice duly given):

     To Option Holder:  Third Security LLC
                        The Governor Tyler
                        1902 Downey Street
                        Radford, VA 24141
                        Telecopy:  (540) 633-7972
                        Attention: Marcus E. Smith, Esquire

     With a Copy to:    Hunton & Williams
                        Riverfront Plaza, East Tower
                        951 East Byrd Street
                        Richmond, Virginia 23219
                        Telecopy: (804) 344-7999
                        Attention: C. Porter Vaughan, Esq.

     To Optionor:       Laidlaw Global Corp.
                        100 Park Avenue
                        New York, New York 10017
                        Telecopy: (212) 949-5139
                        Attention: Mr. Roger Bendelac

     With a Copy to:    Beckman, Millman, Barandes & Douglas, LLP
                        1616 John Street, Suite 1313
                        New York, New York  10038

                                      -8-
<PAGE>

                        Telecopy: (212) 791-7990
                        Attention: Robert Barandes, Esq.

          5.5.  Counterparts.  This Option Agreement may be executed in two
                ------------
or more counterparts, each of which shall be deemed an original, but all of
which together shall constitute one and the same instrument.

          5.6. Severability.  If any provision of this Option Agreement shall be
               ------------
determined to be invalid or unenforceable, the remainder shall be valid and
enforceable to the maximum extent possible.

          5.7. Headings.  The section headings used in this Option Agreement
               --------
are intended principally for convenience and shall not by themselves determine
the rights and obligations of the parties to this Option Agreement.

          5.8. Delay and Waiver.  No delay on the part of any party in
               ----------------
exercising any right under this Option Agreement shall operate as a waiver of
such right. The waiver by any party of any other term or condition of this
Option Agreement shall not be construed as a waiver of a subsequent breach or
failure of the same term or condition or a waiver of any other term or condition
contained in this Option Agreement.

                                      -9-
<PAGE>

  IN WITNESS WHEREOF, the undersigned have executed this Agreement the day and
year first above written.

OPTIONOR:

LAIDLAW GLOBAL CORP.

By:  /s/ Roger Bendelac
     ------------------------------------
     Roger Bendelac
     Chairman and Chief Executive Officer

OPTION HOLDER:

THIRD SECURITY, LLC

By:  /s/ Randal J. Kirk
     ------------------------------------
     Randal J. Kirk
     Manager

                                      -10-
<PAGE>

                                   Exhibit A
                                   ---------

                          Call Option Exercise Notice

                               December __, 2001

Laidlaw Global Corp.
100 Park Avenue
New York, New York 10017

Attention:   Roger Bendelac
             Chairman and Chief Executive Officer

Dear Mr. Bendelac:

     1.  Exercise of Call Option.  Effective as of the above date, the
         -----------------------
undersigned hereby exercises its option to purchase _____ shares of Common Stock
of Laidlaw Global Corp., pursuant to the Call and Put Option Agreement (the
"Option Agreement"), dated December 4, 2001, by and between Laidlaw Global Corp.
(the "Optionor") and Third Security LLC (the "Option Holder").  The exercise
price per share is $_______ for an aggregate purchase price of $_______.
Capitalized terms used but not defined herein shall have their respective
meanings as set forth in the Option Agreement.

     2.   Delivery of Payment.  The undersigned has wire transferred the above
          -------------------
aggregate purchase price to the Optionor and attached is a confirmation of such
transfer.

     3.  Delivery of Shares.  You are instructed to deliver the share
         ------------------
certificates representing the Call Option Shares to the undersigned as required
by the Option Agreement.

Submitted by:

THIRD SECURITY, LLC

By:
     --------------------
     Randal J. Kirk
     Manager

                                      -11-
<PAGE>

                                   Exhibit B
                                   ---------

                           Put Option Exercise Notice

                               ____________, 200_
Laidlaw Global Corp.
100 Park Avenue
New York, New York 10017

Attention:   Roger Bendelac
             Chairman and Chief Executive Officer

Dear Mr. Bendelac:

     1.  Exercise of Put Option.  Effective as of the above date, the
         ----------------------
undersigned hereby exercises its option to sell _____ shares of Common Stock of
Laidlaw Global Corp., pursuant to the Call and Put Option Agreement (the "Option
Agreement"), dated December 4, 2001, by and between Laidlaw Global Corp.  (the
"Optionor") and Third Security LLC (the "Option Holder").  The exercise price
per share is $_______ for an aggregate sales price of $_______ (the "Aggregate
Put Exercise Price").  Capitalized terms used but not defined herein shall have
their respective meanings set forth in the Option Agreement.

     2.   Delivery of Payment.  You are instructed to issue and deliver written
          -------------------
evidence to the Option Holder that the original principal balance of the
Convertible Note shall be increased by an amount equal to the Aggregate Put
Exercise Price (the "Put Shares Convertible Note Increase") for the Put Option
Shares set forth herein.

     3.  Delivery of Shares.  Upon receipt of the evidence of the increase in
         ------------------
the Convertible Note by the Put Shares Convertible Note Increase, the
undersigned will deliver to your attention the share certificates representing
the Put Option Shares together with duly exercised assignments in proper form to
transfer the Put Option Shares as required by the Option Agreement.

Submitted by:

THIRD SECURITY, LLC

By:
     --------------------
     Randal J. Kirk
     Manager

                                      -12-<PAGE>

                                                                    EXHIBIT 10.5

                      ASSIGNMENT AND ASSUMPTION AGREEMENT

     This Assignment and Assumption Agreement (this  "Agreement") is made and
entered into as of December 3, 2001, by and among PACIFIC USA HOLDINGS CORP, a
Texas corporation ("PUSA" or "Assignor"); THIRD SECURITY, LLC, a Virginia
limited liability company ("TS" or "Assignee"); and LAIDLAW GLOBAL CORPORATION,
a Delaware corporation ("Laidlaw").

     WHEREAS, PUSA and Laidlaw executed an Option Agreement (the "Option
Agreement"), dated as of August 31, 2001, pursuant to which PUSA was granted
first rights of refusal to match 100% of any third party offer, on the same
price-per-share terms as any transaction approved by the Board of Directors of
Laidlaw from August 31, 2001 through August 31, 2002 (the "Refusal Rights"); and

     WHEREAS, Paragraph 7 of the Option Agreement provides that PUSA may assign
the Refusal Rights with the consent of Laidlaw, which consent may not be
unreasonably withheld; and

     WHEREAS, on November 29, the Board of Directors of Laidlaw approved a
letter of intent between Laidlaw and Technology Partners (Holdings)
LLC("Technology Partners"), pursuant to which Technology Partners intends to
acquire common stock of Laidlaw on terms as outlined in the letter of intent
(the "Technology Transaction"); and

     WHEREAS, PUSA desires to assign its Refusal Right with respect to the
Technology Transaction to TS and TS desires to assume such right.

     NOW, THEREFORE, in consideration of the mutual covenants herein contained,
the parties agree as follows:

1.   ASSIGNMENT.  PUSA hereby assigns to TS all of its Refusal Right, including
     without limitation with respect to the Technology Transaction.  PUSA hereby
     retains all other rights under the Option Agreement.  The Refusal Right
     shall revert back to PUSA in the event that TS does not close its equity
     investment in Laidlaw.

2.   ASSUMPTION.  TS hereby assumes such Refusal Right and agrees to be bound
     and abide by the terms and conditions of the Option Agreement with respect
     to the Refusal Right.

3.   CONSENT.  Laidlaw hereby acknowledges PUSA's rights under the Option
     Agreement and consents to assignment to TS of the Refusal Right with
     respect to the Technology Transaction.  PUSA hereby consents to, and waives
     any preemptive rights or rights of first refusal it may have, with respect
     to any investment in or loan to Laidlaw made by TS, whether such investment
     or loan is made pursuant to the Refusal Right or otherwise.

4.   EFFECTIVE DATE.  This Agreement shall be effective as of the date first
     above written.

<PAGE>

5.   NOTICES.  Paragraph 5 of the Option Agreement is hereby amended to include
     notice to TS in connection with exercise of the Refusal Right related to
     the Technology Transaction, as follows:

     If to Optionee (with respect to that certain letter of intent between
Optionor and Technology Partners Inc.):

                                    Third Security LLC
                                    Attn: Marcus Smith
                                    The Governor Tyler
                                    1902 Downey Street
                                    Radford, VA  24141

          With courtesy copy to:    Hunton & Williams
                                    Attn: C. Porter Vaughan, Esq.
                                    951 East Byrd Street
                                    Richmond, Virginia 23219

6.   GOVERNING LAW.  This Agreement shall be governed by, and construed and
     -------------
enforced in accordance with, the laws of the State of Texas.

7.   CONSTRUCTION.  The captions and headings contained herein are for
     ------------
convenient reference only and shall not in any way affect the meaning or
interpretation of this Agreement.  Notwithstanding any rule or maxim of
construction to the contrary, any ambiguity or uncertainty in this Agreement
shall not be construed against either party based upon authorship of any of the
provisions hereof.

8.   COUNTERPARTS; FACSIMILES.  This Agreement may be executed in two (2) or
     ------------------------
more counterparts, each of which shall be deemed an original, and all of which
together shall constitute one (1) and the same instrument.  Delivery of an
executed counterpart of a signature page to this agreement by facsimile shall be
effective as delivery of a manually executed counterpart of this agreement.

                            [SIGNATURE PAGE FOLLOWS]

<PAGE>

     IN WITNESS WHEREOF, the parties have executed this Agreement as of the date
first hereinabove written.

                                 ASSIGNOR:

                                 PACIFIC USA HOLDINGS CORP.,
                                 a Texas corporation

                                 By:   /s/ Michael McCraw
                                      ----------------------------------
                                      Name:  Michael McCraw
                                            ----------------------------
                                      Title:  COO/CEO
                                            ----------------------------

                                 ASSIGNEE:

                                 THIRD SECURITY, LLC,
                                 a Virginia limited liability company

                                 By: /s/ Randal J. Kirk
                                     -----------------------------------
                                     Randal J. Kirk
                                     Manager

                                 LAIDLAW:

                                 LAIDLAW GLOBAL CORPORATION,
                                 a Delaware corporation

                                 By:    /s/ Roger E. Bendelac
                                      ----------------------------------
                                      Name:  Roger E. Bendelac
                                            ----------------------------
                                      Title:  Chairman
                                            ----------------------------

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