Document:

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                                                                   EXHIBIT 10.26

                           PURCHASE AND SALE AGREEMENT

                                  by and among

          CANDLEWOOD HOTEL COMPANY, INC. AND CERTAIN OF ITS AFFILIATES,
                                   as Sellers,

                                       and

                          HOSPITALITY PROPERTIES TRUST,
                                  as Purchaser

                           ---------------------------

                                 August 10, 2001

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                                TABLE OF CONTENTS

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SECTION 1.  DEFINITIONS......................................................................2

        1.1   "Agreement"....................................................................2
        1.2   "Agreement to Lease"...........................................................3
        1.3   "Allocable Purchase Price".....................................................3
        1.4   "Assets".......................................................................3
        1.5   "Business Day".................................................................3
        1.6   "Candlewood"...................................................................3
        1.7   "Candlewood Parties"...........................................................3
        1.8   "Closing"......................................................................3
        1.9   "Closing Date".................................................................3
        1.10  "Contracts"....................................................................3
        1.11  "Defective Property"...........................................................3
        1.12  "Documents"....................................................................4
        1.13  "FF&E".........................................................................4
        1.14  "Hotel"........................................................................4
        1.15  "Improvements".................................................................4
        1.16  "Intangible Property"..........................................................4
        1.17  "Lease"........................................................................4
        1.18  "Opening Date".................................................................4
        1.19  "Permitted Encumbrances".......................................................4
        1.20  "Plans and Specifications".....................................................5
        1.21  "Properties"...................................................................5
        1.22  "Purchase Price"...............................................................5
        1.23  "Purchaser"....................................................................5
        1.24  "Real Property"................................................................5
        1.25  "Retained Funds"...............................................................5
        1.26  "Sellers"......................................................................5
        1.27  "Substantial Completion".......................................................5
        1.28  "Surveys"......................................................................6
        1.29  "Tenant".......................................................................6
        1.30  "Tenant Leases"................................................................6
        1.31  "Title Commitments"............................................................6
        1.32  "Title Company"................................................................6

SECTION 2.  PURCHASE AND SALE; DILIGENCE.....................................................6

        2.1  Purchase and Sale...............................................................6
        2.2  Diligence Inspections...........................................................6
        2.3  Defective Properties............................................................7
        2.4  Title Matters...................................................................8
        2.5  Survey Matters..................................................................9

SECTION 3.  PURCHASE AND SALE...............................................................10
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                                TABLE OF CONTENTS

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        3.1   Closing.......................................................................10
        3.2   Purchase Price................................................................11

SECTION 4.  CONDITIONS TO PURCHASER'S OBLIGATION TO CLOSE...................................11

        4.1   Closing Documents.............................................................11
        4.2   Condition of Properties.......................................................12
        4.3   Title Policies and Surveys....................................................13
        4.4   Opinions of Counsel...........................................................13

SECTION 5.  CONDITIONS TO CANDLEWOOD PARTIES' OBLIGATION TO
              CLOSE.........................................................................13

        5.1   Purchase Price................................................................14
        5.2   Closing Documents.............................................................14
        5.3   Opinion of Counsel............................................................14

SECTION 6.  REPRESENTATIONS AND WARRANTIES OF CANDLEWOOD PARTIES............................14

        6.1   Status and Authority of the Candlewood Parties................................14
        6.2   Action of the Candlewood Parties..............................................14
        6.3   No Violations of Agreements...................................................15
        6.4   Litigation....................................................................15
        6.5   Existing Leases, Agreements, Etc..............................................15
        6.6   Disclosure....................................................................15
        6.7   Utilities, Etc................................................................15
        6.8   Compliance With Law...........................................................16
        6.9   Taxes.........................................................................16
        6.10  Not A Foreign Person..........................................................16
        6.11  Hazardous Substances..........................................................16
        6.12  Insurance.....................................................................17
        6.13  Ownership of Sellers..........................................................17
        6.14  Substantial Completion........................................................17
        6.15  Condition of Properties.......................................................17

SECTION 7.  REPRESENTATIONS AND WARRANTIES OF PURCHASER.....................................18

        7.1   Status and Authority of the Purchaser.........................................18
        7.2   Action of the Purchaser.......................................................19
        7.3   No Violations of Agreements...................................................19
        7.4   Litigation....................................................................19

SECTION 8.  COVENANTS OF THE CANDLEWOOD PARTIES.............................................20
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                                TABLE OF CONTENTS

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        8.1   Compliance with Laws, Etc......................................................20
        8.2   Approval of Agreements.........................................................20
        8.3   Notice of Material Changes or Untrue Representations...........................20
        8.4   Substantial Completion.........................................................20
        8.5   Financial Information..........................................................20

SECTION 9.  APPORTIONMENTS...................................................................21

        9.1   Real Property Apportionments...................................................21
        9.2   Closing Costs..................................................................21

SECTION 10.  DEFAULT.........................................................................21

        10.1   Default by the Candlewood Parties.............................................21
        10.2   Default by the Purchaser......................................................22

SECTION 11.  MISCELLANEOUS...................................................................22

        11.1   Agreement to Indemnify........................................................22
        11.2   Brokerage Commissions.........................................................23
        11.3   Publicity.....................................................................24
        11.4   Notices.......................................................................24
        11.5   Waivers, Etc..................................................................25
        11.6   Assignment; Successors and Assigns............................................26
        11.7   Severability..................................................................26
        11.8   Counterparts, Etc.............................................................27
        11.9   Governing Law.................................................................27
        11.10  Performance on Business Days..................................................27
        11.11  Attorneys' Fees...............................................................27
        11.12  Section and Other Headings....................................................28
        11.13  Nonliability of Trustees......................................................28

Schedule A      -  The Properties; Allocable Purchase Prices
Schedule B-1-2  -  Legal Descriptions
Schedule C      -  Form of Surveyor's Certificate
Schedule D      -  Form of Seller's Certificate
Schedule E      -  Form of Architect's Certificate
Schedule F      -  List of Plans and Specifications
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                           PURCHASE AND SALE AGREEMENT

        THIS PURCHASE AND SALE AGREEMENT is made as of the 10th day of August,
2001, by and among (i) CANDLEWOOD HOTEL COMPANY, INC. ("Candlewood"), a Delaware
corporation, (ii) the two entities listed as "sellers" on the signature pages of
this Agreement (each, individually, a "Seller" and collectively, the "Sellers")
and (iii) HOSPITALITY PROPERTIES TRUST, a Maryland real estate investment trust
("Purchaser").

                                   WITNESSETH:

        WHEREAS, the Sellers are the owners of all the Properties (all
capitalized terms used and not otherwise defined herein having the meanings
ascribed to such terms in Section 1); and

        WHEREAS, the Purchaser desires to purchase the Properties, as more fully
set forth below; and

        WHEREAS, the Sellers are willing to sell all of the Properties to the
Purchaser, subject to and upon the terms and conditions hereinafter set forth;
and

        WHEREAS, Candlewood owns, directly or indirectly, all of the outstanding
capital stock of the Sellers and the transactions contemplated by this Agreement
are of direct and material benefit to Candlewood;

        NOW, THEREFORE, in consideration of the mutual covenants herein
contained and other good and valuable consideration, the mutual receipt and
legal sufficiency of which are hereby acknowledged, the Candlewood Parties and
the Purchaser hereby agree as follows:

SECTION 1.     DEFINITIONS

        Capitalized terms used in this Agreement shall have the meanings set
forth below or in the Section of this Agreement referred to below:

        1.1 "AGREEMENT" shall mean this Purchase and Sale Agreement, together
with Schedules A through F attached hereto, as it and they may be amended from
time to time as herein provided.

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        1.2 "AGREEMENT TO LEASE" shall mean that certain Agreement to Lease,
dated as of November 19, 1997, by and between the Purchaser and Candlewood, as
it may be amended, restated, supplemented or otherwise modified from time to
time.

        1.3 "ALLOCABLE PURCHASE PRICE" shall mean, with respect to each
Property, the amount set forth in Schedule A opposite the name of such Property,
it being understood and agreed that the aggregate amount of the Allocable
Purchase Prices of the Properties shall be Twenty-Eight Million Eight Hundred
Fifty Thousand Dollars ($28,850,000).

        1.4 "ASSETS" shall mean, with respect to any Hotel, collectively, all of
the Real Property, the FF&E, the Contracts, the Documents, the Improvements, the
Intangible Property and the Tenant Leases owned by any of the Sellers in
connection with or relating to such Hotel.

        1.5 "BUSINESS DAY" shall mean any day other than a Saturday, Sunday or
any other day on which banking institutions in The Commonwealth of Massachusetts
or the State of New York are authorized by law or executive action to close.

        1.6 "CANDLEWOOD" shall have the meaning given such term in the first
paragraph of this Agreement.

        1.7 "CANDLEWOOD PARTIES" shall mean, collectively, Candlewood and the
Sellers.

        1.8 "CLOSING" shall have the meaning given such term in Section 3.1.

        1.9 "CLOSING DATE" shall have the meaning given such term in Section
3.1.

        1.10 "CONTRACTS" shall mean, with respect to any Property, all hotel
licensing agreements and other service contracts, equipment leases, booking
agreements and other arrangements or agreements to which any of the Sellers is a
party affecting the ownership, repair, maintenance, management, leasing or
operation of such Property, to the extent the Sellers' interest therein is
assignable or transferable.

        1.11 "DEFECTIVE PROPERTY" shall have the meaning given such term in
Section 2.3(a).

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        1.12 "DOCUMENTS" shall mean, with respect to any Property, all books,
records and files relating to the leasing, maintenance, management or operation
of such Property.

        1.13 "FF&E" shall mean, with respect to any Property, all appliances,
machinery, devices, fixtures, appurtenances, equipment, furniture, furnishings
and articles of tangible personal property of every kind and nature whatsoever
(other than motor vehicles) owned by any of the Sellers and located in or at, or
used in connection with the ownership, operation or maintenance of such
Property.

        1.14 "HOTEL" shall mean each hotel located at the properties identified
on Schedule A, the legal descriptions of which are set forth on Schedules B-1
through B-2.

        1.15 "IMPROVEMENTS" shall mean, with respect to any Property, all
buildings, fixtures, walls, fences, landscaping and other structures and
improvements situated on, affixed or appurtenant to the Real Property with
respect to such Property.

        1.16 "INTANGIBLE PROPERTY" shall mean, with respect to any Property, all
transferable or assignable permits, certificates of occupancy, operating
permits, sign permits, development rights and approvals, certificates, licenses,
warranties and guarantees, the Contracts, telephone exchange numbers identified
with such Property held by any of the Sellers and all other transferable
intangible property, miscellaneous rights, benefits and privileges of any kind
or character with respect to such Property held by any of the Sellers.

        1.17 "LEASE" shall mean the lease to be entered into between the
Purchaser or its subsidiary, as landlord, and the Tenant, as tenant, with
respect to the Properties pursuant to the Agreement to Lease, as amended,
modified or supplemented from time to time.

        1.18 "OPENING DATE" shall mean, with respect to any Property, the date
as of which all Improvements located at such Property, including, without
limitation, all guest rooms and/or suites, shall be open for business to the
public as a Candlewood hotel, in accordance with applicable brand standards.

        1.19 "PERMITTED ENCUMBRANCES" shall mean, with respect to any Property,
(a) liens for taxes, assessments and governmental charges with respect to such
Property not yet due and payable or due and payable but not yet delinquent; (b)
applicable zoning

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regulations and ordinances provided the same do not prohibit or impair in any
material respect use of such Property as an extended stay hotel as currently
operated and constructed; (c) such other nonmonetary encumbrances as do not, in
the Purchaser's reasonable opinion, impair marketability and do not materially
interfere with the use of such Property as a fully functioning Candlewood hotel;
(d) UCC Financing Statements which would be permitted pursuant to the terms of
Section 21.9 of the Lease; and (e) such other nonmonetary encumbrances with
respect to such Property which are not objected to by the Purchaser in
accordance with Sections 2.4 and 2.5.

        1.20 "PLANS AND SPECIFICATIONS" shall mean, with respect to each
Property, the plans and specifications identified on Schedule F with respect to
such Property.

        1.21 "PROPERTIES" shall mean, collectively, all of the Assets relating
to the properties identified on Schedule A, the legal descriptions of which are
set forth in Schedules B-1--B-2.

        1.22 "PURCHASE PRICE" shall mean the sum of the Allocable Purchase
Prices, but in no event more than Twenty-Eight Million Eight Hundred Fifty
Thousand Dollars ($28,850,000).

        1.23 "PURCHASER" shall have the meaning given such term in the first
paragraph of this Agreement.

        1.24 "REAL PROPERTY" shall mean, with respect to any Property, the real
property described in the applicable Schedule B-1 through B-2, together with all
easements, rights of way, privileges, licenses and appurtenances which the
Sellers may own with respect thereto.

        1.25 "RETAINED FUNDS" shall mean the sum of Six Hundred Fifty Thousand
Dollars ($650,000).1.26 "REVIEW PERIOD" shall mean the period commencing on the
date of this Agreement and expiring on the first to occur of the date thirty
(30) days after the date of this Agreement and the Closing Date.

        1.26 "SELLERS" shall have the meaning given such term in the first
paragraph of this Agreement.

        1.27 "SUBSTANTIAL COMPLETION" shall mean, with respect to any Property,
physical completion of the Improvements on such Property, including, without
limitation, physical completion of a hotel of the brand and consisting of the
number of rooms set forth on Schedule A, consistent with the Plans and

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Specifications therefor (other than so-called "punch-list" items as do not
individually or in the aggregate impair use of such Property for its intended
use), free of all liens and encumbrances (other than Permitted Encumbrances)
such that the Opening Date shall have occurred and the Improvements may be used
for their intended use.

        1.28 "SURVEYS" shall have the meaning given such term in Section 2.5.

        1.29 "TENANT" shall have the meaning given such term in the Agreement to
Lease.

        1.30 "TENANT LEASES" shall mean, with respect to any Property, all
leases, rental agreements or other agreements (other than agreements for letting
of rooms or other facilities to hotel guests) (including all amendments or
modifications thereto) which entitle any person to have rights with respect to
the use or occupancy of any portion of such Property.

        1.31 "TITLE COMMITMENTS" shall have the meaning given such term in
Section 2.4.

        1.32 "TITLE COMPANY" shall mean First American Title Insurance Company,
or such other title insurance company as shall have been selected by the
Purchaser and approved by the Sellers, which approval shall not be unreasonably
withheld, delayed or conditioned.

SECTION 2.     PURCHASE AND SALE; DILIGENCE

        2.1 PURCHASE AND SALE. In consideration of the mutual covenants herein
contained, the Purchaser hereby agrees to purchase from the Sellers and
Candlewood hereby agrees to cause the Sellers to sell and the Sellers hereby
agree to sell to the Purchaser, all of the Sellers' right, title and interest in
and to the Properties for the Purchase Price, subject to and in accordance with
the terms and conditions of this Agreement.

        2.2 DILIGENCE INSPECTIONS. For the Review Period and, thereafter, until
Closing, the Sellers shall permit the Purchaser and its representatives to
inspect the Properties and the Improvements (including, without limitation, all
roofs, electric, mechanical and structural elements, and HVAC systems therein),
to perform due diligence, soil analysis and environmental investigations, to
examine the books of account and records of the Sellers with respect to the
Properties,

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including, without limitation, all leases and agreements affecting the
Properties, and make copies thereof, at such reasonable times as the Purchaser
or its representatives may request by notice to the Sellers (which notice may be
oral). To the extent that, in connection with such investigations, the
Purchaser, its agents, representatives or contractors, damages or disturbs any
of the Real Property, the Improvements or FF&E located thereon, the Purchaser
shall, at its expense, return the same to substantially the same condition which
existed immediately prior to such damage or disturbance. Neither the Purchaser
nor any of its agents, representatives or contractors shall have any right
whatsoever to alter the condition of any Property, or portion thereof, without
the prior written consent of the Sellers, which consent shall not be
unreasonably withheld, delayed or conditioned. The Purchaser shall indemnify,
defend and hold harmless the Sellers from and against any and all expense, loss
or damage which the Sellers may incur as a result of any act or omission of the
Purchaser or its representatives, agents or contractors in connection with such
examinations and inspections, other than to the extent that any expense, loss or
damage arises from any negligence or misconduct of the Sellers. The provisions
of this Section 2.2 shall survive the termination of this Agreement and the
Closing.

        2.3 DEFECTIVE PROPERTIES. (a) In the event that (i) the Purchaser
reasonably determines that a Property has structural, environmental or other
structural defects or conditions such that (x) expenditures equal to or greater
than three percent (3%) of the Allocable Purchase Price of such Property are
required in order to bring such Property into a reasonably satisfactory
condition in accordance with prevailing standards, as the case may be, for like
hotels, or (y), with respect to Properties as to which the Opening Date has
already occurred, the calculation with respect to such Property of net operating
income varies by three percent (3%) or more of that set forth in the financial
data provided by the Candlewood Parties to the Purchaser prior to the date
hereof (any such Property being hereinafter referred to as a "Defective
Property"), and (ii) the Purchaser gives written notice thereof to the
Candlewood Parties no later than the expiration of the Review Period (time being
of the essence with respect to the giving of such notice), identifying the
Defective Property or Defective Properties and the specific defects with respect
thereto, the Candlewood Parties shall, subject to paragraph (c) below, be
required to permit the Purchaser to acquire all of the Properties other than
such Defective Property or Defective Properties.

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        (a) If, prior to the applicable Closing, (i) any Property suffers a
casualty or condemnation which would cause such Property or Properties to become
a Defective Property, (ii) such Property is not, prior to the Closing, restored
to a condition substantially the same as the condition thereof immediately prior
to such casualty or condemnation, and (iii) the Purchaser provides written
notice of same to the Candlewood Parties no later than the applicable Closing
Date, time being of the essence, the Candlewood Parties shall, subject to
paragraph (c) below, be required to permit the Purchaser to acquire all of the
Properties other than such Defective Property or Properties. Promptly upon
learning of the same, the Candlewood Parties covenant and agree to provide the
Purchaser with prompt written notice of any casualty or condemnation affecting
any Property.

        (b) If the Purchaser timely identifies any Defective Property and the
Purchaser and the Candlewood Parties shall, acting reasonably and in good faith
be unable or unwilling to agree that (x) the Candlewood Parties shall, at their
sole cost, remedy the applicable defect prior to the applicable Closing (in
which event the Candlewood Parties shall have the right to adjourn the
applicable Closing Date for up to ninety (90) days for such purpose), (y) the
Purchaser shall, notwithstanding such defect, acquire the Defective Property
subject to a reduction in the Allocable Purchase Price of the Defective Property
sufficient to compensate the Purchaser for such defect (in which event the
applicable Seller shall retain all available insurance or condemnation proceeds)
or (z) on the substitution of another property owned by the Candlewood Parties
for such Defective Property, this Agreement shall, at the Purchaser's option,
terminate with respect to such Defective Property and the Purchase Price shall
be reduced by the Allocable Purchase Price of such Defective Property.

        2.4 TITLE MATTERS. Promptly upon execution of this Agreement, the
Candlewood Parties shall order from the Title Company and direct the Title
Company promptly to deliver to the Purchaser a preliminary title commitment, for
an ALTA extended owner's policy of title insurance with respect to each of the
Properties, together with complete and legible copies of all instruments and
documents referred to as exceptions to title (collectively, the "Title
Commitments").

        Prior to the expiration of the Review Period, the Purchaser shall give
the Candlewood Parties notice of any title exceptions (other than Permitted
Encumbrances) which adversely affect any Property in any material respect and as
to which the Purchaser

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reasonably objects. If, for any reason, the Candlewood Parties are unable or
unwilling to take such actions as may be required to cause such exceptions to be
removed from the Title Commitments, the Candlewood Parties shall give the
Purchaser notice thereof; it being understood and agreed that the failure of the
Candlewood Parties to give such notice within ten (10) Business Days after the
Purchaser's notice of objection shall be deemed an election by the Candlewood
Parties not to remedy such matters. If the Candlewood Parties shall be unable or
unwilling to remove any title defects to which the Purchaser has reasonably
objected, the Purchaser may elect (i) to terminate this Agreement with respect
to the affected Property, in which event, the Purchase Price shall be reduced by
the Allocable Purchase Price of the affected Properties and this Agreement shall
be of no further force and effect with respect to the affected Properties or
(ii) to consummate the transactions contemplated hereby, notwithstanding such
title defect, without any abatement or reduction in the Purchase Price on
account thereof. The Purchaser shall make any such election by written notice to
the Candlewood Parties given on or prior to the fifth Business Day after the
Candlewood Parties' notice of their unwillingness or inability to cure such
defect. Failure of the Purchaser to give such notice shall be deemed an election
by the Purchaser to proceed in accordance with clause (ii) above and such
exception shall be deemed a Permitted Encumbrance.

        2.5 SURVEY MATTERS. Upon execution of this Agreement, the Candlewood
Parties shall arrange for the preparation of an ALTA survey with respect to each
of the Properties (the "Surveys") by a licensed surveyor in the jurisdiction in
which each such Property is located, which (i) contains an accurate legal
description of the applicable Property, (ii) shows the exact location, dimension
and description (including applicable recording information) of all utilities,
easements, encroachments and other physical matters affecting such Property, the
number of striped parking spaces located thereon and all applicable building
set-back lines, (iii) states whether the applicable Property is located within a
100-year flood plain and (iv) includes a certification in the form set forth in
Schedule C, or such other form as may be acceptable to the Purchaser, addressed
to the Purchaser, the Title Company and any other persons requested by the
Purchaser or designated by the Candlewood Parties.

        Within ten (10) Business Days after receipt of the Surveys, the
Purchaser shall give the Candlewood Parties notice of any matters shown thereon
(other than Permitted Encumbrances) which

                                      -9-
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adversely affect any such Property in any material respect and as to which the
Purchaser reasonably objects. If, for any reason, the Candlewood Parties are
unwilling or unable to take such actions as may be required to remedy the
objectionable matters, the Candlewood Parties shall give the Purchaser prompt
notice thereof; it being understood and agreed that the failure of the
Candlewood Parties to give such notice within ten (10) Business Days after the
Purchaser's notice of objection shall be deemed an election by the Candlewood
Parties not to remedy such matters. If the Candlewood Parties shall be unwilling
or unable to remove any survey defect to which the Purchaser has reasonably
objected, the Purchaser may elect (i) to terminate this Agreement with respect
to the affected Property, in which event, the Purchase Price shall be reduced by
the Allocable Purchase Price of the affected Properties and this Agreement shall
terminate and be of no further force or effect with respect to the affected
Properties or (ii) to consummate the transactions contemplated hereby,
notwithstanding such defect, without any abatement or reduction in the Purchase
Price on account thereof. The Purchaser shall make any such election by written
notice to the Candlewood Parties given on or prior to the fifth Business Day
after the Candlewood Parties' notice of their inability to cure such defect and
time shall be of the essence with respect to the giving of such notice. Failure
of the Purchaser to give such notice shall be deemed an election by the
Purchaser to proceed in accordance with clause (ii) above and such matter shall
be deemed a Permitted Encumbrance.

SECTION 3.     PURCHASE AND SALE

        3.1 CLOSING. The purchase and sale of the Properties shall be
consummated at one or more closings (each, a "Closing") to be held at the
offices of Sullivan & Worcester LLP, One Post Office Square, Boston,
Massachusetts, or at such other location as the Sellers and the Purchaser may
agree, at 10:00 a.m. local time, the Closing with respect to any Property to
occur on a date (each, a "Closing Date") designated in writing by the Sellers,
which date shall not be less than ten (10) Business Days nor more than thirty
(30) Business Days after notice from the Sellers to the Purchaser that
Substantial Completion and the Opening Date have occurred with respect to such
Property (and which notice shall identify the proposed Closing Date) or, if
later, the date as of which all conditions precedent to the Closing herein set
forth with respect to the applicable Property have either been satisfied or
waived by the party in whose favor such conditions run. In the event that
Closings with respect to all of the Properties shall not have occurred on or
before

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August 30, 2001, provided that no action for specific performance shall have
been commenced by the Purchaser to enforce this Agreement, any party shall,
provided such party shall not be in default hereunder, have the right, by the
giving of written notice, to terminate this Agreement with respect to all of the
Properties as to which a Closing has not yet occurred as of the date of
termination.

        3.2 PURCHASE PRICE. The Allocable Purchase Prices shall be payable as
follows:

        (a) At each Closing, the Allocable Purchase Price of each Property being
purchased, less the amount of the Retained Funds with respect thereto, shall be
payable by wire transfer of immediately available funds on the applicable
Closing Date to an account or accounts to be designated by the Sellers prior to
such Closing; and

        (b) Except as otherwise provided in the Lease, the Retained Funds with
respect to each Property shall be payable by wire transfer of immediately
available funds upon the expiration or sooner termination of the Lease, in
accordance with the terms of the Lease, to an account or accounts to be
designated by the Sellers prior to such date.

SECTION 4.     CONDITIONS TO PURCHASER'S OBLIGATION TO CLOSE

        The obligation of the Purchaser to acquire each of the Properties on the
applicable Closing Date shall be subject to the satisfaction of the following
conditions precedent on and as of such Closing Date:

        4.1 CLOSING DOCUMENTS. The applicable Candlewood Parties shall have
delivered to the Purchaser with respect to the applicable Property:

        (a) A good and sufficient warranty deed with covenants against grantor's
acts, or its local equivalent, in proper statutory form for recording, duly
executed and acknowledged by the Sellers, conveying good and marketable title to
the applicable Fee Properties, free from all liens and encumbrances other than
the Permitted Encumbrances;

        (b) A bill of sale and assignment agreement, in form and substance
reasonably satisfactory to the Sellers and the Purchaser, duly executed and
acknowledged by the Sellers, with respect to all of the Sellers' right, title
and interest in, to

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and under the FF&E, the Contracts, the Documents, the Intangible Property and
the Tenant Leases with respect to the Properties and the Sellers' rights under
all builder's warranties with respect to the applicable Property;

        (c) A copy of the final duly issued certificate of occupancy for each of
the applicable Properties;

        (d) A Sellers' closing certificate in the form attached hereto as
Schedule D;

        (e) An architect's certificate in the form attached hereto as Schedule
E;

        (f) A duly executed copy of the Lease, or applicable amendment thereto,
all of the Incidental Documents (as such term is defined in the Lease) and all
other documents and sums required to be delivered by the Candlewood Parties
and/or the Tenant pursuant to the Agreement to Lease;

        (g) Certified copies of all charter documents, applicable corporate
resolutions and certificates of incumbency with respect to the applicable
Candlewood Parties and the Tenant; and

        (h) Such other conveyance documents, certificates, deeds, affidavits and
other instruments as the Purchaser or the Title Company may reasonably require
to effectuate the transactions contemplated by this Agreement.

4.2     CONDITION OF PROPERTIES.

        (a) No material default or event which with the giving of notice and/or
lapse of time could constitute a material default shall have occurred and be
continuing under any material agreement benefiting or affecting the applicable
Properties in any respect;

        (b) No action shall be pending or threatened for the condemnation or
taking by power of eminent domain of all or any material portion of the
applicable Properties which would render any Property a Defective Property;

        (c) All material licenses, permits and other authorizations necessary
for the current use, occupancy and operation of the applicable Properties shall
be in full force and effect;

                                      -12-
<PAGE>

        (d) The Purchaser shall have received an engineer's report, in form and
substance reasonably satisfactory to the Purchaser, confirming that Substantial
Completion has occurred; and

        (e) No Default or Event of Default (as defined therein) shall have
occurred and be continuing under the Lease.

        4.3 TITLE POLICIES AND SURVEYS. (a) The Title Company shall be prepared,
subject only to payment of the applicable premium and endorsement fees and
delivery of all conveyance documents in recordable form, to issue title
insurance policies to the Purchaser with respect to the applicable Properties,
in form and substance reasonably satisfactory to the Purchaser in accordance
with Section 2.4, together with such affirmative coverages as the Purchaser may
reasonably require and shall have been determined by the Title Company as
available prior to the expiration of the Review Period.

        (a) The Purchaser shall have received an as-built survey with respect to
the applicable Properties, such survey to be consistent with the requirements of
Section 2.5.

        4.4 OPINIONS OF COUNSEL. (a) The Purchaser shall have received a written
opinion from counsel to the Candlewood Parties, which counsel shall be
reasonably acceptable to the Purchaser, in form and substance reasonably
satisfactory to the Purchaser, regarding the organization and authority of the
Candlewood Parties and the Tenant, the enforceability of this Agreement, the
Lease or amendment thereto, as the case may be, and the Incidental Documents (as
defined in the Lease) and such other matters with respect to the transactions
contemplated by this Agreement as the Purchaser may reasonably require.

        (a) The Purchaser shall have received a zoning diligence memorandum from
local counsel to the Purchaser, in form and substance reasonably satisfactory to
the Purchaser, regarding the compliance of the Properties with respect to
zoning, licensing and such other matters as the Purchaser may reasonably
require.

SECTION 5.     CONDITIONS TO CANDLEWOOD PARTIES' OBLIGATION TO CLOSE

        The obligation of the Candlewood Parties to convey the Properties on the
applicable Closing Date to the Purchaser is

                                      -13-
<PAGE>

subject to the satisfaction of the following conditions precedent on and as of
such Closing Date:

        5.1 PURCHASE PRICE. The Purchaser shall deliver to the Candlewood
Parties the Allocable Purchase Prices of the applicable Properties as provided
in Section 3.2.

        5.2 CLOSING DOCUMENTS. The Purchaser shall have delivered to the
Sellers:

        (a) Duly executed and acknowledged counterparts of the documents
described in Section 4.1, where applicable; and

        (b) Certified copies of all charter documents, applicable resolutions
and certificates of incumbency with respect to the Purchaser.

        5.3 OPINION OF COUNSEL. The Candlewood Parties shall have received a
written opinion from Sullivan & Worcester LLP, counsel to the Purchaser, in form
and substance reasonably satisfactory to the Candlewood Parties, regarding the
organization and authority of the Purchaser and such other matters with respect
to the transactions contemplated by this Agreement as the Candlewood Parties may
reasonably require.

SECTION 6.     REPRESENTATIONS AND WARRANTIES OF CANDLEWOOD PARTIES

        To induce the Purchaser to enter into this Agreement, each of
Candlewood, with respect to all Properties, and, each Seller, with respect to
its Property, represent and warrant to the Purchaser as follows:

        6.1 STATUS AND AUTHORITY OF THE CANDLEWOOD PARTIES. It is a corporation
or limited liability company duly organized, validly existing and in good
standing under the laws of its state of incorporation or formation, and has all
requisite power and authority under the laws of such state and its respective
charter documents to enter into and perform its obligations under this Agreement
and to consummate the transactions contemplated hereby. It has duly qualified to
transact business in each jurisdiction in which the nature of the business
conducted by it requires such qualification, except where failure to do so could
not reasonably be expected to have a material adverse effect.

        6.2 ACTION OF THE CANDLEWOOD PARTIES. It has taken all necessary action
to authorize the execution, delivery and

                                      -14-
<PAGE>

performance of this Agreement, and upon the execution and delivery of any
document to be delivered by it on or prior to the Closing Date, such document
shall constitute its valid and binding obligation and agreement, enforceable
against such Candlewood Party in accordance with its terms, except as
enforceability may be limited by bankruptcy, insolvency, reorganization,
moratorium or similar laws of general application affecting the rights and
remedies of creditors.

        6.3 NO VIOLATIONS OF AGREEMENTS. Neither the execution, delivery or
performance of this Agreement, nor compliance with the terms and provisions
hereof, will result in any breach of the terms, conditions or provisions of, or
conflict with or constitute a default under, or result in the creation of any
lien, charge or encumbrance upon its Property pursuant to the terms of any
indenture, mortgage, deed of trust, note, evidence of indebtedness or any other
agreement or instrument by which it is bound.

        6.4 LITIGATION. It has received no written notice of and, to its
knowledge, no action or proceeding is pending or threatened and no investigation
looking toward such an action or proceeding has begun, which (a) questions the
validity of this Agreement or any action taken or to be taken pursuant hereto,
(b) will result in any material adverse change in the business, operation,
affairs or condition of its Property, (c) will result in or subject its Property
to a material liability, or (d) involves condemnation or eminent domain
proceedings against any material part of its Property.

        6.5 EXISTING LEASES, AGREEMENTS, ETC. Other than any agreements provided
to the Purchaser not less than ten (10) days prior to the expiration of the
Review Period, there are no other material agreements affecting its Property
which will be binding on the Purchaser subsequent to the Closing Date which the
Purchaser cannot terminate on thirty (30) days notice without payment of premium
or penalty.

        6.6 DISCLOSURE. To its knowledge, there is no fact or condition which
materially and adversely affects the business or condition of its Property which
has not been set forth in this Agreement or in the other documents, certificates
or statements furnished to the Purchaser in connection with the transactions
contemplated hereby.

        6.7 UTILITIES, ETC. To its knowledge, all utilities and services
necessary for the use and operation of its Property

                                      -15-
<PAGE>

(including, without limitation, road access, gas, water, electricity and
telephone) are available thereto and are of sufficient capacity to meet
adequately all needs and requirements necessary for the current use and
operation of its Property. To its knowledge, no fact, condition or proceeding
exists which would result in the termination or material impairment of the
furnishing of such utilities to its Property.

        6.8 COMPLIANCE WITH LAW. To its knowledge, except as disclosed to the
Purchaser in writing not less than ten (10) days' prior to the expiration of the
Review Period, including in any engineering report, (i) its Property and the
current use and operation thereof do not violate any material federal, state,
municipal and other governmental statutes, ordinances, by-laws, rules,
regulations or any other legal requirements, including, without limitation,
those relating to construction, occupancy, zoning, adequacy of parking,
environmental protection, occupational health and safety and fire safety
applicable thereto; and (ii) at the time of the applicable Closing there will be
in effect all material licenses, permits and other authorizations necessary for
the current use, occupancy and operation thereof. Except as disclosed to the
Purchaser in writing not less than ten (10) days' prior to the expiration of the
Review Period, none of the Candlewood Parties has received written notice of any
threatened request, application, proceeding, plan, study or effort which would
materially adversely affect the present use or zoning of its Property or which
would modify or realign any adjacent street or highway in a material and adverse
way.

        6.9 TAXES. To its knowledge, other than the amounts disclosed by tax
bills, no taxes or special assessments of any kind (special, bond or otherwise)
are or have been levied with respect to its Property, or any portion thereof,
which are outstanding or unpaid, other than amounts not yet due and payable or,
if due and payable, not yet delinquent.

        6.10 NOT A FOREIGN PERSON. It is not a "foreign person" within the
meaning of Section 1445 of the United States Internal Revenue Code of 1986, as
amended, and the treasury regulations promulgated thereunder.

        6.11 HAZARDOUS SUBSTANCES. Except as disclosed to the Purchaser or as
described in any environmental report delivered to the Purchaser prior to the
expiration of the Review Period, to its knowledge, neither it nor any tenant or
other occupant or user of any of its Property, or any portion thereof, has
stored

                                      -16-
<PAGE>

or disposed of (or engaged in the business of storing or disposing of) or has
released or caused the release of any hazardous waste, contaminants, oil,
radioactive or other material on its Property, or any portion thereof, the
removal of which is required or the maintenance of which is prohibited or
penalized by any applicable Federal, state or local statutes, laws, ordinances,
rules or regulations, and, to each of the Candlewood Party's knowledge, except
as disclosed to the Purchaser or as described in any environmental report
delivered to the Purchaser prior to the expiration of the Review Period, its
Property is free from any such hazardous waste, contaminants, oil, radioactive
and other materials, except any such materials maintained in accordance with
applicable law.

        6.12 INSURANCE. It has not received written notice from any insurance
carrier of defects or inadequacies in its Property which, if uncorrected, would
result in a termination of insurance coverage or a material increase in the
premiums charged therefor.

        6.13 OWNERSHIP OF SELLERS. Candlewood is the sole owner, directly or
indirectly, of all of the issued and outstanding beneficial interests in the
Sellers and the transactions contemplated by this Agreement are of direct
material benefit to Candlewood.

        6.14 SUBSTANTIAL COMPLETION. As of the date hereof, Substantial
Completion of all of the Properties has occurred.

        6.15 CONDITION OF PROPERTIES. To its knowledge, its Property is, or on
the applicable Closing Date will be, in good working order and repair,
mechanically and structurally sound, free from material defects in materials and
workmanship.

        The representations and warranties made in this Agreement by the
Candlewood Parties are made as of the date hereof and shall be deemed remade by
the Candlewood Parties as of the applicable Closing Date for the Property or
Properties then being conveyed by the Sellers, with the same force and effect as
if made on, and as of, such date; provided, however, that, the Candlewood
Parties shall have the right, from time to time prior to the applicable Closing
Date, with respect to any Property as to which a Closing has not yet occurred,
to modify the representations and warranties by notice to the Purchaser and, in
such event, the Purchaser shall have the rights provided in Section 2.3. All
representations and warranties made in this

                                      -17-
<PAGE>

Agreement by the Candlewood Parties shall survive the applicable Closing for a
period of one year thereafter.

        Except as otherwise expressly provided in this Agreement or any
documents to be delivered to the Purchaser at the Closing, the Candlewood
Parties disclaim the making of any representations or warranties, express or
implied, regarding the Properties or matters affecting the Properties, whether
made by the Candlewood Parties, on the Candlewood Parties' behalf or otherwise,
including, without limitation, the physical condition of the Properties, title
to or the boundaries of the Real Property, pest control matters, soil
conditions, the presence, existence or absence of hazardous wastes, toxic
substances or other environmental matters, compliance with building, health,
safety, land use and zoning laws, regulations and orders, structural and other
engineering characteristics, traffic patterns, market data, economic conditions
or projections, and any other information pertaining to the Properties or the
market and physical environments in which they are located. The Purchaser
acknowledges (i) that the Purchaser has entered into this Agreement with the
intention of making and relying upon its own investigation or that of third
parties with respect to the physical, environmental, economic and legal
condition of each Property and (ii) that the Purchaser is not relying upon any
statements, representations or warranties of any kind, other than those
specifically set forth in this Agreement or in any document to be delivered to
the Purchaser at any Closing, made by the Candlewood Parties or anyone acting on
the Candlewood Parties' behalf. The Purchaser further acknowledges that it has
not received from or on behalf of the Candlewood Parties any accounting, tax,
legal, architectural, engineering, property management or other advice with
respect to this transaction and is relying solely upon the advice of third party
accounting, tax, legal, architectural, engineering, property management and
other advisors. Subject to the provisions of this Agreement, the Purchaser shall
purchase the Properties in their "as is" condition on each Closing Date.

SECTION 7.     REPRESENTATIONS AND WARRANTIES OF PURCHASER

        To induce the Candlewood Parties to enter in this Agreement, the
Purchaser represents and warrants to the Candlewood Parties as follows:

        7.1 STATUS AND AUTHORITY OF THE PURCHASER. The Purchaser is a Maryland
real estate investment trust duly organized, validly existing and in trust good
standing under the laws of

                                      -18-
<PAGE>

the State of Maryland, and has all requisite power and authority under the laws
of such state and under its charter documents to enter into and perform its
obligations under this Agreement and to consummate the transactions contemplated
hereby. The Purchaser has duly qualified and is in good standing as a trust or
unincorporated business association in each jurisdiction in which the nature of
the business conducted by it requires such qualification, except where the
failure to do so could not reasonably be expected to have a material adverse
effect.

        7.2 ACTION OF THE PURCHASER. The Purchaser has taken all necessary
action to authorize the execution, delivery and performance of this Agreement,
and upon the execution and delivery of any document to be delivered by the
Purchaser on or prior to the Closing Date such document shall constitute the
valid and binding obligation and agreement of the Purchaser, enforceable against
the Purchaser in accordance with its terms, except as enforceability may be
limited by bankruptcy, insolvency, reorganization, moratorium or similar laws of
general application affecting the rights and remedies of creditors.

        7.3 NO VIOLATIONS OF AGREEMENTS. Neither the execution, delivery or
performance of this Agreement by the Purchaser, nor compliance with the terms
and provisions hereof, will result in any breach of the terms, conditions or
provisions of, or conflict with or constitute a default under, or result in the
creation of any lien, charge or encumbrance upon any property or assets of the
Purchaser pursuant to the terms of any indenture, mortgage, deed of trust, note,
evidence of indebtedness or any other agreement or instrument by which the
Purchaser is bound.

        7.4 LITIGATION. No investigation, action or proceeding is pending and,
to the Purchaser's knowledge, no action or proceeding is threatened and no
investigation looking toward such an action or proceeding has begun, which
questions the validity of this Agreement or any action taken or to be taken
pursuant hereto.

        The representations and warranties made in this Agreement by the
Purchaser shall be continuing and shall be deemed remade by the Purchaser as of
the applicable Closing Date with the same force and effect as if made on, and as
of, such date. The Purchaser's liability with respect to all representations and
warranties made in this Agreement by the Purchaser shall survive the applicable
Closing for a period of one (1) year thereafter.

                                      -19-
<PAGE>

SECTION 8.     COVENANTS OF THE CANDLEWOOD PARTIES

        Candlewood, with respect to all Properties, and each Seller, with
respect to its Property, hereby covenant with the Purchaser between the date of
this Agreement and the Closing Date as follows:

        8.1 COMPLIANCE WITH LAWS, ETC. To comply or to cause compliance with in
all material respects with (i) all applicable laws, regulations and other
requirements from time to time of every governmental body having jurisdiction of
its Property or the use or occupancy of the Improvements located on the Real
Property and (ii) all terms, covenants and conditions of all instruments of
record and other agreements affecting its Property.

        8.2 APPROVAL OF AGREEMENTS. Except as otherwise authorized by this
Agreement or in the ordinary course of business, not to enter into, modify,
amend or terminate any other agreement with respect to its Property which would
encumber or be binding upon its Property from and after the applicable Closing
Date without in each instance obtaining the prior written consent of the
Purchaser, which consent shall not be unreasonably withheld, delayed or
conditioned.

        8.3 NOTICE OF MATERIAL CHANGES OR UNTRUE REPRESENTATIONS. Upon learning
of any material change in any condition with respect to its Property or of any
event or circumstance which makes any representation or warranty of the
Candlewood Parties to the Purchaser under this Agreement untrue or misleading in
any material respect, promptly to notify the Purchaser thereof (the Purchaser
agreeing, on learning of any such fact or condition, promptly to notify the
Candlewood Parties thereof).

        8.4 SUBSTANTIAL COMPLETION. Intentionally deleted.

        8.5 FINANCIAL INFORMATION. To provide to the Purchaser, promptly upon
request at the Candlewood Parties' sole cost and expense, such audited and
unaudited financial and other information and certifications of the Candlewood
Parties with respect to the Candlewood Parties and the Properties as the
Purchaser may from time to time reasonably request in order to comply with any
applicable securities laws and/or any rules, regulations or requirements of the
Securities and Exchange Commission and, if required or requested, to permit the
Purchaser to incorporate by reference any information included in filings made
by Candlewood with the Securities and Exchange

                                      -20-
<PAGE>

Commission. Notwithstanding the foregoing, the Candlewood Parties shall not be
required to provide, pursuant to this Agreement, audited financial information
with respect to individual Properties, unless the Purchaser shall pay for the
cost thereof.

SECTION 9.     APPORTIONMENTS

        9.1 REAL PROPERTY APPORTIONMENTS. Representatives of the Purchaser and
the Candlewood Parties shall perform any and all of the adjustments and
apportionments which are appropriate and usual for a transaction of this nature
and taking into account the simultaneous execution of the Lease. The adjustments
hereunder shall be calculated or paid in an amount based upon a fair and
reasonable estimated accounting performed and agreed to by representatives of
the Candlewood Parties and the Purchaser at or prior to the Closing. Subsequent
final adjustments and payments shall be made in cash or other immediately
available funds as soon as practicable after the Closing Date and in any event
within ninety (90) days after such Closing Date, based upon an agreed accounting
performed by representatives of the Candlewood Parties and the Purchaser. In the
event the parties have not agreed with respect to the adjustments required to be
made pursuant to this Section 9.1 within such ninety-day period, upon
application by either party, Ernst & Young, LLP or other certified public
accountants reasonably acceptable to the Purchaser and the Candlewood Parties
shall determine any such adjustments which have not theretofore been agreed to
between the Candlewood Parties and the Purchaser. The charges of such accountant
shall be borne by the Candlewood Parties.

        9.2 CLOSING COSTS. The Candlewood Parties shall pay all costs and
expenses associated with the transactions contemplated hereby, including,
without limitation, recording costs, title insurance premiums, the costs and
expenses of preparing engineering and environmental reports, market studies and
appraisals and the reasonable costs and expenses of legal counsel retained by
the Purchaser.

        The obligations of the parties under this Section 9 shall survive the
Closing.

SECTION 10.    DEFAULT

        10.1 DEFAULT BY THE CANDLEWOOD PARTIES. If the Candlewood Parties shall
have made any representation or warranty herein which shall be untrue or
misleading in any material respect, or

                                      -21-
<PAGE>

if the Candlewood Parties shall fail to perform any of the material covenants
and agreements contained herein to be performed by the Candlewood Parties and
such failure continues for a period of ten (10) days after notice thereof from
the Purchaser or if the Tenant shall default in its obligations under the
Agreement to Lease and such default shall continue beyond the expiration of any
applicable cure period, the Purchaser may terminate this Agreement and/or the
Purchaser may pursue any and all remedies available to it at law or in equity,
including, but not limited to, a suit for specific performance or other
equitable relief.

        10.2 DEFAULT BY THE PURCHASER. If the Purchaser shall have made any
representation or warranty herein which shall be untrue or misleading in any
material respect, or if the Purchaser shall fail to perform any of the covenants
and agreements contained herein to be performed by it and such failure shall
continue for a period of ten (10) days after notice thereof from the Candlewood
Parties or if the Purchaser shall default in its obligations under the Agreement
to Lease and such default shall continue beyond the expiration of any applicable
cure period, the Candlewood Parties may, as its sole and exclusive remedy at law
and in equity, terminate this Agreement. In the event that the Candlewood
Parties shall so terminate this Agreement, the Purchaser shall thereupon pay to
the Candlewood Parties, as liquidated damages and not as a penalty, the sum of
Two Hundred Fifty Thousand Dollars ($250,000) plus all expenses incurred by the
Candlewood Parties in connection with the transactions contemplated hereby,
whereupon, the Purchaser shall have no further monetary or, except as expressly
provided herein, nonmonetary obligations hereunder.

SECTION 11.    MISCELLANEOUS

        11.1 AGREEMENT TO INDEMNIFY. (a) Subject to any express provisions of
this Agreement to the contrary, (i) the Candlewood Parties shall indemnify and
hold harmless the Purchaser from and against any and all obligations, claims,
losses, damages, liabilities, and expenses (including, without limitation,
reasonable attorneys' and accountants' fees and disbursements) arising out of
(x) events, contractual obligations, acts or omissions of the Candlewood Parties
that occurred in connection with the ownership or operation of any Property
prior to the Closing or (y) any damage to property of others or injury to or
death of any person or any claims for any debts or obligations occurring on or
about or in connection with any Property or any portion thereof at any time or
times prior to the Closing, and

                                      -22-
<PAGE>

(ii) the Purchaser shall indemnify and hold harmless the Candlewood Parties from
and against any and all obligations, claims, losses, damages, liabilities and
expenses (including, without limitation, reasonable attorneys' and accountants'
fees and disbursements) arising out of (x) events, contractual obligations, acts
or omissions of Purchaser that occur in connection with the ownership or
operation of any Property on or after the Closing, or (y) any damage to property
of others or injury to or death of any person or any claims for any debts or
obligations occurring on or about any Property or any portion thereof at any
time or times after the Closing.

        (b) Whenever it is provided in this Agreement that an obligation of the
Candlewood Parties will be assumed by the Purchaser on or after the Closing, the
Purchaser shall be deemed to have also agreed to indemnify and hold harmless the
Candlewood Parties and their respective successors and assigns from and against
all claims, losses, damages, liabilities, costs, and expenses (including,
without limitation, reasonable attorneys' and accountants' fees and expenses)
arising from any failure of the Purchaser to perform the obligation so assumed
on or after the Closing.

        (c) Whenever either party shall learn through the filing of a claim or
the commencement of a proceeding or otherwise of the existence of any liability
for which the other party is or may be responsible under this Agreement, the
party learning of such liability shall notify the other party promptly and
furnish such copies of documents (and make originals thereof available) and such
other information as such party may have that may be used or useful in the
defense of such claims and shall afford said other party full opportunity to
defend the same in the name of such party and shall generally cooperate with
said other party in the defense of any such claim.

        (d) The provisions of this Section 11.1 shall survive the Closing and
the termination of this Agreement.

        11.2 BROKERAGE COMMISSIONS. Each of the parties hereto represents to the
other parties that it dealt with no broker, finder or like agent in connection
with this Agreement or the transactions contemplated hereby. The Candlewood
Parties shall be solely responsible for and shall indemnify and hold harmless
the Purchaser and its respective legal representatives, heirs, successors and
assigns from and against any loss, liability or expense, including, reasonable
attorneys' fees, arising out of any claim or claims for commissions or other
compensation for

                                      -23-
<PAGE>

bringing about this Agreement or the transactions contemplated hereby made by
any broker, finder or like agent other than such loss, liability or expense
arising from the Purchaser's breach of its representation made in this Section
11.2. The provisions of this Section 11.2 shall survive the Closing and any
termination of this Agreement.

        11.3 PUBLICITY. The parties agree that no party shall, with respect to
this Agreement and the transactions contemplated hereby, contact or conduct
negotiations with public officials, make any public pronouncements, issue press
releases or otherwise furnish information regarding this Agreement or the
transactions contemplated to any third party without the consent of the other
parties, which consent shall not be unreasonably withheld, delayed or
conditioned, except as required by law or unless such action is taken based on
advice of counsel given in good faith. No party, or its employees shall trade in
the securities of any parent or affiliate of the Sellers or of the Purchaser
until a public announcement of the transactions contemplated by this Agreement
has been made. No party shall record this Agreement or any notice thereof,
except as required by law or unless such action is taken based on advice of
counsel given in good faith.

        11.4 NOTICES. (a) Any and all notices, demands, consents, approvals,
offers, elections and other communications required or permitted under this
Agreement shall be deemed adequately given if in writing and the same shall be
delivered either in hand, by telecopier with written acknowledgment of receipt,
or by mail or Federal Express or similar expedited commercial carrier, addressed
to the recipient of the notice, postpaid and registered or certified with return
receipt requested (if by mail), or with all freight charges prepaid (if by
Federal Express or similar carrier).

        (b) All notices required or permitted to be sent hereunder shall be
deemed to have been given for all purposes of this Agreement upon the date of
acknowledged receipt, in the case of a notice by telecopier, and, in all other
cases, upon the date of receipt or refusal, except that whenever under this
Agreement a notice is either received on a day which is not a Business Day or is
required to be delivered on or before a specific day which is not a Business
Day, the day of receipt or required delivery shall automatically be extended to
the next Business Day.

        (c) All such notices shall be addressed,

                                      -24-
<PAGE>

        if to the Candlewood Parties to:

               Candlewood Hotel Company, Inc.
               8621 E. 21st Street North, Suite 200
               Wichita, Kansas  67206
               Attn:  Mr. Tim Johnson
               [Telecopier No. (316) 631-1382]

         with a copy to:

               Latham & Watkins
               233 South Wacker Drive, Suite 5800
               Chicago, Illinois  60606
               Attn:  Kenneth Crews, Esq.
               [Telecopier No. (312) 993-9767]

        If to the Purchaser, to:

               Hospitality Properties Trust
               400 Centre Street
               Newton, Massachusetts  02458
               Attn:  Mr. John G. Murray
               [Telecopier No. (617) 969-5730]

        with a copy to:

               Sullivan & Worcester LLP
               One Post Office Square
               Boston, Massachusetts  02109
               Attn:  Nancy S. Grodberg, Esq.
               [Telecopier No. (617) 338-2880]

        (d) By notice given as herein provided, the parties hereto and their
respective successors and assigns shall have the right from time to time and at
any time during the term of this Agreement to change their respective addresses
effective upon receipt by the other parties of such notice and each shall have
the right to specify as its address any other address within the United States
of America.

        11.5 WAIVERS, ETC. Any waiver of any term or condition of this
Agreement, or of the breach of any covenant, representation or warranty
contained herein, in any one instance, shall not operate as or be deemed to be
or construed as a further or continuing waiver of any other breach of such term,
condition, covenant, representation or warranty or any other term, condition,
covenant, representation or warranty, nor shall any failure at any time or times
to enforce or require performance

                                      -25-
<PAGE>

of any provision hereof operate as a waiver of or affect in any manner such
party's right at a later time to enforce or require performance of such
provision or any other provision hereof. This Agreement may not be amended, nor
shall any waiver, change, modification, consent or discharge be effected, except
by an instrument in writing executed by or on behalf of the party against whom
enforcement of any amendment, waiver, change, modification, consent or discharge
is sought.

        11.6 ASSIGNMENT; SUCCESSORS AND ASSIGNS. This Agreement and all rights
and obligations hereunder shall not be assignable by any party without the
written consent of the other parties, except that (x) Purchaser may assign this
Agreement to any entity wholly owned, directly or indirectly, by the Purchaser
(provided, however, that, in the event this Agreement shall be assigned to any
entity wholly owned, directly or indirectly, by the Purchaser, Hospitality
Properties Trust shall remain liable for the obligation of the "Purchaser"
hereunder) and (y) after the Closing, the Sellers may assign its surviving
rights, if any, under this Agreement to the Tenant. This Agreement shall be
binding upon and shall inure to the benefit of the parties hereto and their
respective legal representatives, successors and permitted assigns. This
Agreement is not intended and shall not be construed to create any rights in or
to be enforceable in any part by any other persons.

        11.7 SEVERABILITY. If any provision of this Agreement shall be held or
deemed to be, or shall in fact be, invalid, inoperative or unenforceable as
applied to any particular case in any jurisdiction or jurisdictions, or in all
jurisdictions or in all cases, because of the conflict of any provision with any
constitution or statute or rule of public policy or for any other reason, such
circumstance shall not have the effect of rendering the provision or provisions
in question invalid, inoperative or unenforceable in any other jurisdiction or
in any other case or circumstance or of rendering any other provision or
provisions herein contained invalid, inoperative or unenforceable to the extent
that such other provisions are not themselves actually in conflict with such
constitution, statute or rule of public policy, but this Agreement shall be
reformed and construed in any such jurisdiction or case as if such invalid,
inoperative or unenforceable provision had never been contained herein and such
provision reformed so that it would be valid, operative and enforceable to the
maximum extent permitted in such jurisdiction or in such case.

                                      -26-
<PAGE>

        11.8 COUNTERPARTS, ETC. This 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. This Agreement
constitutes the entire agreement of the parties hereto with respect to the
subject matter hereof and shall supersede and take the place of any other
instruments purporting to be an agreement of the parties hereto relating to the
subject matter hereof.

        11.9 GOVERNING LAW. This Agreement shall be interpreted, construed,
applied and enforced in accordance with the laws of The Commonwealth of
Massachusetts applicable to contracts between residents of Massachusetts which
are to be performed entirely within Massachusetts, regardless of (i) where this
Agreement is executed or delivered; or (ii) where any payment or other
performance required by this Agreement is made or required to be made; or (iii)
where any breach of any provision of this Agreement occurs, or any cause of
action otherwise accrues; or (iv) where any action or other proceeding is
instituted or pending; or (v) the nationality, citizenship, domicile, principal
place of business, or jurisdiction of organization or domestication of any
party; or (vi) whether the laws of the forum jurisdiction otherwise would apply
the laws of a jurisdiction other than The Commonwealth of Massachusetts; or
(vii) any combination of the foregoing.

        To the maximum extent permitted by applicable law, any action to
enforce, arising out of, or relating in any way to, any of the provisions of
this Agreement may be brought and prosecuted in such court or courts located in
The Commonwealth of Massachusetts as is provided by law; and the parties consent
to the jurisdiction of said court or courts located in The Commonwealth of
Massachusetts and to service of process by registered mail, return receipt
requested, or by any other manner provided by law.

        11.10 PERFORMANCE ON BUSINESS DAYS. In the event the date on which
performance or payment of any obligation of a party required hereunder is other
than a Business Day, the time for payment or performance shall automatically be
extended to the first Business Day following such date.

        11.11 ATTORNEYS' FEES. If any lawsuit or arbitration or other legal
proceeding arises in connection with the interpretation or enforcement of this
Agreement, the prevailing party therein shall be entitled to receive from the
other party the prevailing party's costs and expenses, including reasonable

                                      -27-
<PAGE>

attorneys' fees incurred in connection therewith, in preparation therefor and on
appeal therefrom, which amounts shall be included in any judgment therein.

        11.12 SECTION AND OTHER HEADINGS. The headings contained in this
Agreement are for reference purposes only and shall not in any way affect the
meaning or interpretation of this Agreement.

        11.13 NONLIABILITY OF TRUSTEES. THE DECLARATION OF TRUST ESTABLISHING
THE PURCHASER, A COPY OF WHICH, TOGETHER WITH ALL AMENDMENTS THERETO (THE
"DECLARATION"), IS DULY FILED WITH THE DEPARTMENT OF ASSESSMENTS AND TAXATION OF
THE STATE OF MARYLAND, PROVIDES THAT THE NAME "HOSPITALITY PROPERTIES TRUST"
REFERS TO THE TRUSTEES UNDER THE DECLARATION COLLECTIVELY AS TRUSTEES, BUT NOT
INDIVIDUALLY OR PERSONALLY, AND THAT NO TRUSTEE, OFFICER, SHAREHOLDER, EMPLOYEE
OR AGENT OF THE PURCHASER SHALL BE HELD TO ANY PERSONAL LIABILITY, JOINTLY OR
SEVERALLY, FOR ANY OBLIGATION OF, OR CLAIM AGAINST, THE PURCHASER. ALL PERSONS
DEALING WITH THE PURCHASER, IN ANY WAY, SHALL LOOK ONLY TO THE ASSETS OF THE
PURCHASER FOR THE PAYMENT OF ANY SUM OR THE PERFORMANCE OF ANY OBLIGATION.

                                      -28-
<PAGE>

        IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed as a sealed instrument as of the date first above written.

                               CANDLEWOOD PARTIES:

                               CANDLEWOOD HOTEL COMPANY, INC.

                               By:___________________________________________
                                    Its (Vice) President

                               CANDLEWOOD PHILADELPHIA-MT. LAUREL, NJ, LLC
                               CANDLEWOOD LAS VEGAS, NV, LLC

                               BY:  CANDLEWOOD HOTEL COMPANY, INC., SOLE MEMBER

                                    By:______________________________________
                                       Name:
                                       Its:

                               PURCHASER:

                                 HOSPITALITY PROPERTIES TRUST

                                 By:_________________________________________
                                             Its (Vice) President

<PAGE>

                                   SCHEDULE A

                                 THE PROPERTIES

<TABLE>
<CAPTION>
LOCATION                                           ALLOCABLE PURCHASE PRICE
<S>                                                <C>
Las Vegas, NV                                            $ 22,000,000
Mt. Laurel, NJ                                              6,850,000
                                                         ------------
                                                         $ 28,850,000
                                                         ============
</TABLE>

<PAGE>

                            SCHEDULE B-1 THROUGH B-2

                        LEGAL DESCRIPTIONS OF PROPERTIES

                             [See attached copies.]

<PAGE>

                                   SCHEDULE C

                         FORM OF SURVEYOR'S CERTIFICATE

                             SURVEYOR'S CERTIFICATE

TO:     Hospitality Properties Trust
        and its assignees or nominees
        400 Centre Street
        Newton, MA  02458

RE:     Survey Entitled "_______________________________________"
        dated _________ ___, 2001, prepared by

        The undersigned hereby certifies that the above-referenced survey was
prepared from an actual on-the-ground instrument survey of the subject premises;
that the same accurately shows the location of the boundaries of the subject
premises and the location of all streets, highways, alleys and public ways
crossing or abutting said premises; that the dimensions of the improvements and
the locations thereof with respect to the boundaries are accurately shown as the
same were situated on ___________ ___, 2001; that there are no encroachments by
improvements appurtenant to adjoining premises upon the subject premises, nor
from the subject premises, unless shown thereon; that all buildings and
structures, if any, lie wholly within all applicable building restriction lines,
if any, and do not violate any restriction or other recorded agreements set
forth in the title insurance commitment for the subject premises dated
__________ __, 2001, issued to you by _________ Title Insurance Company,
Commitment No. _______ (the "Title Policy"); that all easements and rights of
way which are appurtenant to or burden the subject premises and (i) are referred
to in the Title Commitment or (ii) are apparent from a visual inspection are
delineated thereon, and are located other than through the existing building
shown hereon; that all parking spaces, if any, are delineated thereon; and that,
except as otherwise shown thereon, the subject premises are not located (x)
within any flood hazard or flood way area or district as designed by Federal,
state or municipal authority or (y) within any area subject to regulation by
Federal, state or municipal authority as inland or coastal wetlands, beach,
estuary or the like.

<PAGE>

        Access to and egress from the subject premises and the improvements and
structures thereon to ________ Street, a public way, are provided by the means
indicated thereon. Municipal water, storm sewer facilities and telephone, gas
and electric services of public utilities are available in the locations
indicated thereon.

        The undersigned hereby certifies that the square footage of each parcel
delineated on the above-referenced survey is as set forth thereon, that all such
parcels are contiguous without any strips, gaps or gores existing between any of
said parcels, and that said parcels, when combined, form and create one complete
and uninterrupted parcel without any strips, gaps or gores.

        This survey is made in accordance with the "Minimum Standard Detail
Requirements for Land Title Surveys" jointly established and adopted by ALTA and
ACSM in 1999.

Dated: _________ ___, 2001              ________________________________________
                                                  Registered Land Surveyor

                                        __________#_______________

[Surveyor's Seal]

<PAGE>

                                   SCHEDULE D

                          FORM OF SELLERS' CERTIFICATE

                               CLOSING CERTIFICATE

        Reference is made to the Purchase and Sale Agreement, dated __________
(the "Purchase Agreement"). Capitalized terms used and not otherwise defined
herein shall have the meanings ascribed to such terms in the Purchase Agreement.

        In connection with the consummation of the transactions contemplated by
the Purchase and Sale Agreement with respect to the properties described on
Exhibit A, the undersigned hereby certifies as follows:

        1. That Substantial Completion has occurred with respect to the
Properties listed on Exhibit A;

        2. That the Improvements on the Properties listed on Exhibit A include
the number of rooms as set forth in Exhibit A;

        3. That the Opening Date with respect to each of the Properties listed
on Exhibit A is the date therein set forth; and

        4. That the Properties are being operated as a ____________ hotel as set
forth in Exhibit A.

        Executed under seal as of this ____ day of __________, 2001.

                                            ____________________________________

                                            By:_________________________________
                                                     Its (Vice) President

<PAGE>

                                    EXHIBIT A

                                     NO. OF
PROPERTY              BRAND          ROOMS          OPENING DATE

<PAGE>

                                   SCHEDULE E

                         FORM OF ARCHITECT'S CERTIFICATE

                                                             __________ __, 2001

        Reference is made to the Purchase and Sale Agreement, dated __________
(the "Purchase Agreement"), by and between ___________________________, as
sellers, and Hospitality Properties Trust, as purchaser (together with its
successors and assigns ("HPT").

        As an inducement to HPT to acquire the properties identified on Exhibit
A to this letter (the "Properties"), we do hereby:

               1. Certify to HPT that we are professional architects, duly
        registered under the laws and applicable regulations of the State of
        ______________;

               2. Certify to HPT that, to our knowledge, the Plans and
        Specifications identified on Exhibit B (the "Plans") comply with all
        applicable requirements of all governmental authorities having
        jurisdiction over the improvements located on the Properties, including,
        without limitation, all applicable zoning laws, ordinances, rules,
        regulations and restrictions (but excluding any such ordinances, rules,
        regulations and restrictions relating to environmental matters); and

               3. Certify to HPT that the improvements have been substantially
        completed in accordance with the Plans.

                                            Very truly yours,

                                            ____________________________________

                                            By:_________________________________
                                                   Its:

<PAGE>

                                    EXHIBIT A

                                 THE PROPERTIES

                             [See attached copies.]

<PAGE>

                                    EXHIBIT B

                            PLANS AND SPECIFICATIONS

                             [See attached copies.]

<PAGE>

                                   SCHEDULE F

                        LIST OF PLANS AND SPECIFICATIONS

                             [See attached copies.]<PAGE>
                                                                     Exhibit 4.1
--------------------------------------------------------------------------------

                             BECKMAN COULTER, INC.,

                                    AS ISSUER

                 COULTER CORPORATION AND HYBRITECH INCORPORATED,

                                  AS GUARANTORS

                                       AND

                                 CITIBANK, N.A.

                                   AS TRUSTEE

                      ------------------------------------

                          FIRST SUPPLEMENTAL INDENTURE

                         Dated as of November ___, 2001

                     --------------------------------------

           Supplemental to Senior Indenture dated as of April 25, 2001

--------------------------------------------------------------------------------

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                      PAGE

                           ARTICLE I

<S>                   <C>                                                                            <C>
DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

Section 101.          Definitions.......................................................................1

Section 102.          Conflicts with Base Indenture.....................................................7

                          ARTICLE II
                         FORM OF NOTES

Section 201.          Form of Notes.....................................................................8

                          ARTICLE III
                           THE NOTES

Section 301.          Amount; Series; Terms.............................................................8

Section 302.          Denominations.....................................................................8

Section 303.          Execution, Authentication, Delivery and Dating....................................9

Section 304.          Book-Entry Provisions for Global Securities.......................................9

Section 305.          Add On Notes.....................................................................10

Section 306.          Use of Proceeds..................................................................11

                          ARTICLE IV
                   REDEMPTION OF SECURITIES

Section 401.          Optional Redemption..............................................................11

                           ARTICLE V
                    COVENANTS AND REMEDIES

Section 501.          Limitation on Liens..............................................................11

Section 502.          Limitation on Sale and Leaseback Transactions....................................12

Section 503.          Future Note Guarantors...........................................................13

Section 504.          Events of Default................................................................13

Section 505.          Limitations on Consolidation, Etc................................................15

</TABLE>

                                       i
<PAGE>

                       TABLE OF CONTENTS
                          (CONTINUED)
<TABLE>
<CAPTION>
                                                                                                      PAGE
                          ARTICLE VI
                      THE NOTE GUARANTEES

<S>                 <C>                                                                              <C>
Section 601.          Unconditional Guarantee..........................................................16

Section 602.          Additional Note Guarantors.......................................................17

Section 603.          Release of a Note Guarantee......................................................18

Section 604.          Waiver of Subrogation............................................................18

Section 605.          Reliance on Judicial Order or Certificate of Liquidating Agent
                      Regarding Dissolution............................................................19

Section 606.          Article VI Applicable to Paying Agents...........................................19

Section 607.          No Suspension of Remedies........................................................19

                          ARTICLE VII

Section 701.          Supplemental Indentures with Consent of Holders..................................19

                         ARTICLE VIII
                         MISCELLANEOUS

Section 801.          Sinking Funds....................................................................19

Section 802.          Confirmation of Indenture........................................................20

Section 803.          Counterparts.....................................................................20

Section 804.          Governing Law....................................................................20

EXHIBIT A             Form of Note.....................................................................A-1
EXHIBIT B             Form of Supplemental Indenture in Respect of Note Guarantee......................B-1

</TABLE>

                                       ii
<PAGE>

                  FIRST SUPPLEMENTAL INDENTURE, dated as of November ___, 2001
(this "Supplemental Indenture"), among Beckman Coulter, Inc., a corporation duly
organized and existing under the laws of the State of Delaware (the "Company"),
Coulter Corporation, a corporation duly organized and existing under the laws of
the State of Delaware, Hybritech Incorporated, a corporation duly organized and
existing under the laws of the State of California (the "Guarantors"), and
Citibank, N.A., a national banking association duly organized and existing under
the laws of the United States of America, as Trustee (the "Trustee") under the
Senior Indenture dated as of April 25, 2001 between the Company and the Trustee
(the "Base Indenture").

                  WHEREAS, Section 901 (7) of the Base Indenture provides that
the Company and Trustee, at any time and from time to time, may enter into one
or more indentures supplemental to the Base Indenture to establish the form or
terms of Securities of any series as permitted by Sections 201 and 301 thereof;

                  WHEREAS, the Base Indenture also provides for the issuance
from time to time of unsecured senior debentures, notes or other evidences of
indebtedness (the "Securities");

                  WHEREAS, the Company has duly authorized the creation of a
series of its Securities denominated as the "o% Senior Notes Due 2011" (the
"Notes");

                  WHEREAS, the Guarantors are executing this Supplemental
Indenture pursuant to which the Guarantors will guarantee the Company's
obligations under the Notes on the terms and conditions set forth herein;

                  WHEREAS, the entry into this Supplemental Indenture by the
parties hereto is in all respects authorized by the provisions of the Base
Indenture; and

                  WHEREAS, the Company has duly authorized the execution and
delivery of this Supplemental Indenture, to establish the Notes as provided for
in this Supplemental Indenture, and to make this Supplemental Indenture a valid
agreement of the Company, in accordance with their and its terms:

                  NOW, THEREFORE, for and in consideration of the premises and
purchase of the Notes issued on or after the date of this Supplemental Indenture
by the Holders thereof, it is mutually covenanted and agreed, for the equal and
proportionate benefit of all Holders of the Notes, as follows:

                                    Article I

                       DEFINITIONS AND OTHER PROVISIONS OF
                               GENERAL APPLICATION

Section 101.  Definitions.

                  Capitalized terms used herein and not otherwise defined herein
have the meanings assigned to them in the Base Indenture. The words "herein",
"hereof" and "hereby" and other

<PAGE>

words of similar import used in this Supplemental Indenture refer to this
Supplemental Indenture as a whole and not to any particular section hereof.

                As used herein, the following terms have the specified meanings:

                  "Add On Notes" has the meaning specified in Section 305 of
this Supplemental Indenture.

                  "Attributable Value," when used with respect to any sale and
leaseback transaction means, as of the time of determination, the total
obligation (discounted to present value at the interest rate assumed in making
calculations in accordance with FAS 13) of the lessee for rental payments (other
than amounts required to be paid on account of property taxes as well as
maintenance, repairs, insurance, water rates and other items which do not
constitute payments for property rights) during the remaining portion of the
base term of the lease included in such sale and leaseback transaction.

                  "Bank Indebtedness" means any and all Indebtedness or other
amounts payable under or in respect of the Credit Facility or any refinancing in
respect thereof, and any Refinancing Indebtedness in respect thereof, including
in each case (without limitation) principal, premium (if any), interest
(including interest accruing on or after the filing of any petition in
bankruptcy or for reorganization relating to the Company or any Restricted
Subsidiary whether or not a claim for post-filing interest is allowed in such
proceedings), fees, charges, expenses, reimbursement obligations, Guarantees,
other monetary obligations of any nature and all other amounts payable under or
in respect of any of the foregoing.

                  "Base Indenture" has the meaning specified in the recitals of
this Supplemental Indenture.

                  "Business Day" means each Monday, Tuesday, Wednesday, Thursday
and Friday which is not a day on which banking institutions in New York, New
York are authorized or obligated by law or executive order to close.

                  "Capital Lease Obligation" of any Person means, at the time
any determination thereof is to be made, the amount of the liability in respect
of a capital lease for property leased by such Person that would at such time be
required to be capitalized on the balance sheet of such Person in accordance
with GAAP.

                  "Capital Stock" of any Person means (1) in the case of a
corporation, corporate stock; (2) in the case of an association, limited
liability company or business entity, any and all Equity Interests; (3) in the
case of a partnership, partnership interests (whether general or limited); and
(4) any other interest or participation that confers on a Person the right to
receive a share of the profits and losses of, or distributions of assets of, the
issuing Person, including any Preferred Stock.

                  "Commodity Price Protection Agreement" means any forward
contract, commodity swap, commodity option or other similar financial agreement
or arrangement relating to, or the value of which is dependent upon,
fluctuations in commodity prices, but shall not

                                       2
<PAGE>

include contracts for the purchase of raw materials by the Company or any
Restricted Subsidiary for its own use at fixed prices in the ordinary course of
business.

                  "Company" has the meaning specified in the recitals of this
Supplemental Indenture.

                  "Comparable Treasury Issue" means the United States Treasury
security selected by the Reference Treasury Dealer as having a maturity
comparable to the remaining term of the Notes to be redeemed that would be
utilized, at the time of selection and in accordance with customary financial
practice, in pricing new issues of corporate debt securities of comparable
maturity to the remaining term of the Notes.

                  "Comparable Treasury Price" means, with respect to any
redemption date, (A) the average of the Reference Treasury Dealer Quotations for
such redemption date, after excluding the highest and lowest such Reference
Treasury Dealer Quotations, or (B) if the trustee obtains fewer than three such
Reference Treasury Dealer Quotations, the average of all such Quotations, or (C)
if only one Reference Treasury Dealer Quotation is received, such Quotation.

                  "Consolidated Net Tangible Assets" means the aggregate amount
of assets (less applicable reserves and other properly deductible items) after
deducting therefrom (1) all current liabilities (excluding any indebtedness for
money borrowed having a maturity of less than 12 months from the date of the
most recent consolidated balance sheet of the Company but which by its terms is
renewable or extendable beyond 12 months from such date at the option of the
borrower); and (2) all goodwill, trade names, patents, unamortized debt discount
and expense and any other like intangibles, all as set forth on the most recent
consolidated balance sheet of the Company and computed in accordance with GAAP.

                  "Credit Agreement" means the credit agreement dated as of
October 31, 1997, among the Company, the banks and other financial institutions
party thereto from time to time, the initial issuing bank named therein,
Citicorp USA, Inc., as agent and Citicorp Securities, Inc., as arranger, as such
agreement may be amended, supplemented, waived or otherwise modified from time
to time, or refunded, refinanced, restructured, replaced, renewed, repaid,
increased or extended from time to time (whether in whole or in part, whether
with the original agents and lenders or other agents and lenders or otherwise,
and whether provided under the original Credit Agreement or otherwise).

                  "Credit Facility" means the collective reference to the Credit
Agreement, any notes and letters of credit issued pursuant thereto and any
guarantees, security agreements, pledges, mortgages, letter of credit
applications and other collateral documents, and other instruments and
documents, executed and delivered pursuant to or in connection with any of the
foregoing, in each case as the same may be amended, supplemented, waived or
otherwise modified from time to time, or refunded, refinanced, restructured,
replaced, renewed, repaid, increased or extended from time to time (whether in
whole or in part, whether with the original agents and lenders or other agents
and lenders or otherwise, and whether provided under the original Credit
Agreement or otherwise).

                                       3
<PAGE>

                  "Currency Hedging Arrangements" means one or more of the
following agreements which shall be entered into by one or more financial
institutions: foreign exchange contracts, currency swap agreements or other
similar agreements or arrangements designed to protect against the fluctuations
in currency values.

                  "Default" means any event that is, or after the giving of
notice or passage of time or both would be, an Event of Default.

                  "Depositary" means The Depositary Trust Company.

                  "Disqualified Stock" means:

                  (1) any Preferred Stock of any Restricted Subsidiary; and

                  (2) any Capital Stock that, by its terms (or by the terms of
                      any security into which such Capital Stock is convertible
                      or for which such Capital Stock is exchangeable), or upon
                      the happening of any event, matures or is mandatorily
                      redeemable, pursuant to a sinking fund obligation or
                      otherwise, or is redeemable at the option of the holder
                      thereof (other than upon a change of control of the
                      Company in circumstances where the holders of the Notes
                      would have similar rights), in whole or in part on or
                      prior to the Stated Maturity of the Notes.

                  "Dollar" means a dollar or other equivalent unit in such coin
or currency of the United States as at the time shall be legal tender for the
payment of public and private debt.

                  "Equipment Held for Resale" means instrument systems and
related accessories and components manufactured or assembled by the Company that
are owned and held for placement in facilities of the Company's customers.

                  "Equity Interest" in any Person means any and all shares,
interests, rights to purchase, warrants, options, participations or other
equivalents of or interests in (however designated) corporate stock or other
equity participations, including limited liability company interests, in such
Person.

                  "Fair Market Value" means, with respect to any asset or
property, the sale value that would be obtained in an arm's-length transaction
between an informed and willing seller under no compulsion to sell and an
informed and willing buyer under no compulsion to buy.

                  "GAAP" means generally accepted accounting principles in the
United States of America as in effect on the date hereof, including those set
forth in the opinions and pronouncements of the Accounting Principles Board of
the American Institute of Certified Public Accountants and statements and
pronouncements of the Financial Accounting Standards Board or in such other
statement by such other entity as approved by a significant segment of the
United States accounting profession.

                  "Guarantee" means any obligation, contingent or otherwise, of
any Person directly or indirectly guaranteeing any Indebtedness or other
obligation of any other Person, and

                                       4
<PAGE>

any obligation, direct or indirect, contingent or otherwise, of such Person (1)
to purchase or pay (or advance or supply funds for the purchase or payment of)
such Indebtedness or other obligation of such Person (whether arising by virtue
of partnership arrangements, or by agreement to keep well, to purchase assets,
goods, securities or services, to take-or-pay, or to maintain financial
statement conditions or otherwise); or (2) entered into for purposes of assuring
in any other manner the obligee of such Indebtedness or other obligation of the
payment thereof or to protect such obligee against loss in respect thereof (in
whole or in part), provided, however, that the term "Guarantee" shall not
include endorsements for collection or deposit in the ordinary course of
business. The term "Guarantee" used as a verb has a corresponding meaning.

                  "Guarantors" means each of Coulter Corporation, Hybritech
Incorporated and any Restricted Subsidiary that has issued a Note Guarantee.

                  "Indebtedness" means, with respect to any Person, without
duplication, and whether or not contingent (1) all indebtedness of such Person
for borrowed money or which is evidenced by a note, bond, debenture or similar
instrument; (2) all obligations of such Person to pay the deferred or unpaid
purchase price of property or services, which purchase price is due more than
one year after the date of placing such property in service or taking delivery
and title thereto or the completion of such service; (3) all Capital Lease
Obligations of such Person; (4) all obligations of such Person in respect of
letters of credit or bankers' acceptances issued or created for the account of
such Person; (5) to the extent not otherwise included in this definition, all
net obligations of such Person under all Interest Rate Agreements, Currency
Hedging Arrangements or Commodity Price Protection Agreements of such Person;
(6) all liabilities of others of the kind described in the preceding clause (1),
(2) or (3) secured by any Lien on any property owned by such Person even if such
Person has not assumed or otherwise become liable for the payment thereof, to
the extent of the value of the property subject to such Lien; (7) all
Disqualified Stock issued by such Person; and (8) to the extent not otherwise
included, any Guarantee by such Person of any other Person's indebtedness or
other obligations described in clauses (1) through (7) above. "Indebtedness" of
the Company and its Restricted Subsidiaries shall not include (1) current trade
payables incurred in the ordinary course of business and payable in accordance
with customary practices; and (2) non-interest bearing installment obligations
and accrued liabilities incurred in the ordinary course of business which are
not more than 90 days past due.

                  "Indenture" means the Base Indenture as originally executed,
as supplemented by this Supplemental Indenture and as it may from time to time
be supplemented or amended by one or more indentures supplemental thereto
entered into pursuant to the applicable provisions thereof, including, for all
purposes of that instrument and any such supplemental indenture, the provisions
of the Trust Indenture Act that are deemed to be a part of and govern that
instrument and any such supplemental indenture, respectively.

                  "Indenture Obligations" means the obligations of the Company
and any other obligor under this Supplemental Indenture or under the Notes, to
pay principal of, premium, if any, and interest on the Notes when due and
payable, whether at maturity, by acceleration, call for redemption or repurchase
or otherwise, and all other amounts due or to become due under or in connection
with this Supplemental Indenture, the Notes or the Note Guarantees and the
performance of all other obligations to the Trustee (including, but not limited
to, payment of all

                                       5
<PAGE>

amounts due the Trustee under Section 607 of the Base Indenture) and the Holders
of the Notes under this Indenture, the Notes and the Note Guarantees, according
to the terms thereof.

                  "Interest Rate Agreements" means one or more of the following
agreements which shall be entered into by one or more financial institutions:
interest rate protection agreements (including, without limitation, interest
rate swaps, caps, floors, collars and similar agreements) and/or other types of
interest rate hedging agreements from time to time.

                  "Lien" means, with respect to any property or assets, any
mortgage or deed of trust, pledge, hypothecation, assignment, security interest,
lien, encumbrance, or other security arrangement of any kind or nature
whatsoever on or with respect to such property or assets (including any
conditional sale or other title retention agreement having substantially the
same economic effect as any of the foregoing).

                  "Note Guarantee" means each guarantee of the Notes by the
Guarantors hereunder and any guarantee of the Notes that may from time to time
be executed and delivered pursuant to the terms of this Supplemental Indenture.

                  "Notes" has the meaning specified in the recitals of this
Supplemental Indenture.

                  "Officer" means the Chairman of the Board, the Chief Executive
Officer, the Chief Financial Officer, the President, any Vice President, the
Treasurer or the Secretary of the Company.

                  "Person" means any individual, corporation, partnership, joint
venture, association, joint-stock company, limited liability company, trust,
unincorporated organization or government or any agency or political subdivision
thereof.

                  "Preferred Stock" as applied to the Capital Stock of any
Person, means Capital Stock of any class or classes (however designated) which
is preferred as to the payment of dividends or distributions, or as to the
distribution of assets upon any voluntary or involuntary liquidation or
dissolution of such Person, over Capital Stock of any other class of such
Person.

                  "Principal Property" means any real property of the Company or
any of its Subsidiaries, and any equipment located at or comprising a part of
any such property, having a net book value, as of the date of determination, in
excess of the greater of $50 million and 10% of Consolidated Net Tangible Assets
of the Company; provided, however, that Principal Property shall not include
Equipment Held for Resale.

                  "Redemption Date," when used with respect to any Note, means
the date specified for redemption by the Company.

                  "Reference Treasury Dealer" means (A) Salomon Smith Barney
Inc. or Morgan Stanley & Co. Incorporated (or their respective affiliates which
are Primary Treasury Dealers), and their respective successors; provided,
however, that if any of the foregoing shall cease to be a primary U.S.
Government securities dealer in New York City (a "Primary Treasury Dealer"), the
Company will substitute therefor another Primary Treasury Dealer; and (B) any
other Primary Treasury Dealer(s) selected by the Company.

                                       6
<PAGE>

                  "Reference Treasury Dealer Quotation" means, with respect to
each Reference Treasury Dealer and any Redemption Date, the average, as
determined by the Trustee, of the bid and asked prices for the Comparable
Treasury Issue (expressed in each case as a percentage of its principal amount)
quoted in writing to the Trustee by such Reference Treasury Dealer at 5:00 p.m.
(New York City time) on the third Business Day preceding such Redemption Date.

                  "Refinancing Indebtedness" means any Indebtedness incurred in
connection with or given in exchange for the renewal, extension, substitution,
refunding, defeasance, refinancing, repayment or replacement (a "refinancing")
of any Indebtedness.

                  "Restricted Subsidiary" means any Subsidiary of the Company
which owns or leases a Principal Property.

                  "Securities" has the meaning specified in the recitals of this
Supplemental Indenture.

                  "Securities Custodian" means the custodian with respect to a
Global Note (as appointed by the Depositary) or any successor thereto, who shall
initially be the Trustee.

                  "Significant Subsidiary" means each Subsidiary that is a
"significant subsidiary" for purposes of Rule 1-02 of Regulation S-X under the
Securities Act.

                  "Stated Maturity" means, when used with respect to any
security, the date specified in such security as the fixed date on which the
payment of principal of such security is due and payable, including pursuant to
any mandatory redemption provision (but excluding any provision providing for
the purchase of such security at the option of the holder thereof upon the
happening of any contingency beyond the control of the issuer unless such
contingency has occurred).

                  "Subsidiary" of a Person means a Person more than 50% of the
outstanding voting stock or other Equity Interests of which is owned, directly
or indirectly, by the Company or by one or more other Subsidiaries, or by the
Company and one or more other Subsidiaries. For the purposes of this definition,
"voting" stock or other Equity Interests means stock or other Equity Interests
which ordinarily have voting power for the election of directors, trustees or
similar managers, whether at all times or only so long as no senior class of
stock or other Equity Interests has such voting power by reason of any
contingency.

                  "Supplemental Indenture" has the meaning specified in the
recitals of this Supplemental Indenture.

                  "Treasury Rate" means, with respect to any Redemption Date,
the rate per annum equal to the semiannual equivalent yield to maturity of the
Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue
(expressed as a percentage of its principal amount) equal to the Comparable
Treasury Price for such Redemption Date.

                                       7
<PAGE>

Section 102.  Conflicts with Base Indenture.

                  In the event that any provision of this Supplemental Indenture
limits, qualifies or conflicts with a provision of the Base Indenture, such
provision of this Supplemental Indenture shall control.

                                   Article II

                                  FORM OF NOTES

Section 201.  Form of Notes.

                  The Notes shall be substantially in the form of Exhibit A
hereto which is hereby incorporated in and expressly made a part of this
Indenture.

                                   Article III

                                    THE NOTES

Section 301.  Amount; Series; Terms.

                  The title of the Notes shall be "o% Senior Notes Due 2011."
The aggregate principal amount of Notes that may be authenticated and delivered
under this Supplemental Indenture shall be initially limited to $o, subject to
increase as set forth in Section 305.

                  The final Stated Maturity of the Notes shall be November o,
2011. The Notes shall bear interest at the rate of o% per annum, from o or from
the most recent Interest Payment Date to which interest has been paid or duly
provided for, as further provided in the form of Note annexed hereto as Exhibit
A. The Interest Payment Dates on which such interest shall be payable shall be
May o and November o of each year, and the Regular Record Dates for any interest
payable on each such Interest Payment Date shall be the immediately preceding o
and o, respectively.

                  The principal of, and premium, if any, and interest on the
Notes shall be payable at the office or agency of the Company maintained for
that purpose in the Borough of Manhattan, The City of New York, provided,
however, that at the option of the Company payment of interest on any Notes may
be made by check mailed to the address of the Person entitled thereto as such
address shall appear in the Security Register.

                  The Notes will be redeemable at the option of the Company as
provided in Article IV hereof. The Notes will not be entitled to the benefit of
a sinking fund.

                  The Notes will be issued in the form of one or more Global
Securities, deposited with the Trustee as custodian for the Depositary or its
nominee, duly executed by the Company and authenticated by the Trustee as
provided in Section 303 and the Base Indenture.

                                       8
<PAGE>

Section 302.  Denominations.

                  The Notes of each series shall be issuable only in registered
form without coupons and only in denominations of $1,000 and any integral
multiple thereof.

Section 303.  Execution, Authentication, Delivery and Dating.

                  The Notes shall be executed on behalf of the Company by its
Chairman of the Board, its Vice Chairman of the Board, its Chief Executive
Officer, its President, its Chief Financial Officer or one of its Vice
Presidents, and attested by its Secretary or one of its Assistant Secretaries.
The signature of any of these officers on the Notes may be manual or facsimile.

                  Notes bearing the manual or facsimile signatures of
individuals who were at any time the proper officers of the Company shall bind
the Company, notwithstanding that such individuals or any of them have ceased to
hold such offices prior to the authentication and delivery of such Notes or did
not hold such offices at the date of such Notes.

                  On Company Order, the Trustee shall authenticate for original
issue Notes in an aggregate principal amount specified in the Company Order. The
Trustee shall be entitled to receive an Officers' Certificate and an Opinion of
Counsel of the Company that it may reasonably request in connection with such
authentication of Notes. Such Company Order shall specify the amount of Notes to
be authenticated and the date on which the original issue of Notes is to be
authenticated.

                  Each Note shall be dated the date of its authentication.

                  No Note shall be entitled to any benefit under this Indenture
or be valid or obligatory for any purpose unless there appears on such Note a
certificate of authentication substantially in the form provided for in the Base
Indenture executed by the Trustee by manual signature, and such certificate upon
any Note shall be conclusive evidence, and the only evidence, that such Note has
been duly authenticated and delivered hereunder.

Section 304.  Book-Entry Provisions for Global Securities.

                  (a) Each Global Security initially shall (i) be registered in
the name of the Depositary for such Global Securities or the nominee of such
Depositary, (ii) be delivered to the Trustee as custodian for such Depositary
and (iii) bear legends as set forth in Section 204 of the Base Indenture.

                  Members of, or participants in, the Depositary ("Agent
Members") shall have no rights under this Indenture with respect to any Global
Security, and the Depositary may be treated by the Company, the Note Guarantors,
the Trustee and any agent of the Company, the Note Guarantors or the Trustee as
the absolute owner of such Global Security for all purposes whatsoever.
Notwithstanding the foregoing, nothing herein shall prevent the Company, the
Note Guarantors, the Trustee or any agent of the Company, the Note Guarantors or
the Trustee from giving effect to any written certification, proxy or other
authorization furnished by the Depositary or impair, as between the Depositary
and its Agent Members, the operation of

                                       9
<PAGE>

customary practices governing the
exercise of the rights of a beneficial owner of any Security. The registered
holder of a Global Security may grant proxies and otherwise authorize any
person, including Agent Members and persons that may hold interests through
Agent Members, to take any action which a Holder is entitled to take under this
Indenture or the Global Securities.

                  (b) Transfers of a Global Security shall be limited to
transfers of such Global Security in whole, but not in part, to the Depositary,
its successors or their respective Nominees. Interests of beneficial owners in a
Global Security may be transferred or exchanged for physical Notes in accordance
with the applicable rules and procedures of the Depositary and the provisions of
Sections 305 of the Base Indenture.

                  (c) In connection with any transfer or exchange of a portion
of the beneficial interest in any Global Security to beneficial owners for
physical Notes pursuant to paragraph (b), the Security Registrar shall record on
its books and records the date and a decrease in the principal amount of such
Global Security in an amount equal to the beneficial interest in the Global
Security being transferred, and the Company shall execute, and the Trustee shall
authenticate and deliver, one or more physical Notes of like tenor and principal
amount of authorized denominations.

                  (d) In connection with a transfer of an entire Global Security
to beneficial owners pursuant to paragraph (b), the applicable Global Security
shall be deemed to be surrendered to the Trustee for cancellation, and the
Company shall execute, and the Trustee shall authenticate and deliver, to each
beneficial owner identified by the Depositary in exchange for its beneficial
interest in the applicable Global Security, an equal aggregate principal amount
at maturity of physical Notes of authorized denominations.

                  (e) Any beneficial interest in one of the Global Securities
that is transferred to a Person who takes delivery in the form of an interest in
the other Global Security will, upon transfer, cease to be an interest in such
Global Security and become an interest in the other Global Security and,
accordingly, will thereafter be subject to all transfer restrictions, if any,
and other procedures applicable to beneficial interests in such other Global
Security for as long as it remains such an interest.

Section 305.  Add On Notes.

                  The Company may, from time to time, subject to compliance with
any other applicable provisions of this Indenture, without the consent of the
Holders, create and issue pursuant to this Indenture additional notes ("Add On
Notes") having terms and conditions set forth in Exhibit A identical to those of
the other Notes, except that Add On Notes:

                  (i)  may have a different issue date from other Outstanding
         Notes;

                  (ii) may have a different amount of interest payable on the
         first Interest Payment Date after issuance than is payable on other
         Outstanding Notes;

                  (iii) may have terms specified in the Add On Note Board
         Resolution or Add On Note Supplemental Indenture for such Add On Notes
         making appropriate adjustments to this Article III and Exhibit A (and
         related definitions) applicable to such Add On Notes

                                       10
<PAGE>

         in order to conform to and ensure compliance with the Securities Act
         (or other applicable securities laws).

Section 306.  Use of Proceeds.

                  The Company intends to apply the proceeds from the sale of the
Notes solely, directly or indirectly, in the Company's U.S. operations. In
applying the proceeds from the sale of the Notes, the Company represents that,
in no event, will any portion of the proceeds from the sale of the Notes be used
to repay the portion of any indebtedness, the proceeds of which were used to
previously fund any foreign investment or the working capital needs of any
foreign Subsidiary, foreign affiliate or other foreign entity. The Company
further represents that, in no event, will any portion of the proceeds of the
sale of the Notes be used to fund any foreign investment or the working capital
needs of any foreign Subsidiary, foreign affiliate or other foreign entity.

                                   Article IV

                            REDEMPTION OF SECURITIES

Section 401.  Optional Redemption.

                  The Notes will be redeemable, in whole or in part, at the
option of the Company at any time at a redemption price equal to the greater of
(i) 100% of the principal amount of such Notes or (ii) the sum of the present
values of the remaining scheduled payments of principal and interest on the
Notes being redeemed on that Redemption Date (not including any portion of any
payments of interest accrued to the Redemption Date) discounted to the
Redemption Date on a semi-annual basis at the Treasury Rate, as determined by
the Reference Treasury Dealer, plus 10 basis points; plus, in each case, accrued
and unpaid interest on the Notes to the Redemption Date. Procedures for any such
redemption shall be as set forth in Article XI of the Base Indenture.

                                    Article V

                             COVENANTS AND REMEDIES

Section 501.  Limitation on Liens.

                  The Company will not, and will not permit any Restricted
Subsidiary to, create, incur, issue, assume or guarantee any Indebtedness of the
Company or any Subsidiary secured by a Lien upon any Principal Property, or upon
shares of Capital Stock or evidences of indebtedness issued by any Restricted
Subsidiary and owned by the Company or any Restricted Subsidiary, now owned or
hereafter owned by the Company, without making effective provision to secure all
of the Notes then outstanding by such Lien, equally and ratably with any and all
other Indebtedness thereby secured, so long as such Indebtedness shall be so
secured.

                  The foregoing restrictions shall not apply, however, to (1)
Liens on any property existing at the time of the acquisition thereof; (2) Liens
on property of a corporation existing at the time such corporation is merged
into or consolidated with the Company or a Restricted

                                       11
<PAGE>

Subsidiary or at the time of a sale, lease or other disposition of the
properties of such corporation (or a division thereof) as an entirety or
substantially as an entirety to the Company or a Restricted Subsidiary, provided
that such Lien as a result of such merger, consolidation, sale, lease or other
disposition is not extended to property owned by the Company or such Restricted
Subsidiary immediately prior thereto; (3) Liens on property of a corporation
existing at the time such corporation becomes a Restricted Subsidiary; (4) Liens
securing indebtedness of a Restricted Subsidiary to the Company or to another
Restricted Subsidiary; (5) Liens to secure all or part of the cost of
acquisition, construction, development or improvement of the underlying
property, or to secure indebtedness incurred to provide funds for any such
purpose, provided that the commitment of the creditor to extend the credit
secured by any such Lien shall have been obtained not later than twenty-four
months after the later of (a) the completion of the acquisition, construction,
development or improvement of such property or (b) the placing in operation of
such property or of such property as so constructed, developed or improved; (6)
Liens on any property created, assumed or otherwise brought into existence in
contemplation of the sale or other disposition of the underlying property,
whether directly or indirectly, by way of share disposition or otherwise;
provided that the Company must have disposed of such property within 180 days
from the creation of such Liens and any indebtedness secured by such Liens shall
be without recourse to the Company or any Subsidiary; (7) Liens in favor of the
United States of America or any State thereof, or any department, agency or
instrumentality or political subdivision thereof, to secure partial, progress,
advance or other payments; (8) Liens to secure indebtedness of joint ventures in
which the Company or a Restricted Subsidiary has an interest, to the extent such
Liens are on property or assets of, or equity interests in, such joint ventures;
(9) Liens on Equipment Held for Resale; and (10) any indebtedness secured by
Liens existing on the date of this Supplemental Indenture or any extension,
renewal or replacement or refunding of any Lien existing on the date of this
Supplemental Indenture or referred to in clauses (1) to (3) or (5); provided,
however, that the aggregate principal amount of indebtedness secured thereby and
not otherwise authorized by clauses (1) to (3) or (5), shall not exceed the
aggregate principal amount of indebtedness, plus any premium or fee payable in
connection with any such extension, renewal, replacement, or refunding, so
secured at the time of such extension, renewal, replacement or refunding.

                  Notwithstanding the restrictions described above, the Company
and its Restricted Subsidiaries may incur, issue, assume or guarantee
Indebtedness secured by Liens without equally and ratably securing the Notes
then outstanding, provided, that at the time of such incurrence, issuance,
assumption or guarantee, after giving effect thereto and to the retirement of
any Indebtedness which is concurrently being retired, the aggregate amount of
all outstanding Indebtedness secured by Liens so incurred, other than any
Indebtedness secured by Liens permitted as described in clauses (1) through (10)
above, and together with all outstanding Attributable Value of all sale and
leaseback transactions permitted as described in Section 502 of this
Supplemental Indenture does not exceed 15% of the Consolidated Net Tangible
Assets of the Company.

Section 502.  Limitation on Sale and Leaseback Transactions.

                  The Company will not, and will not permit any Restricted
Subsidiary to, engage in any sale and leaseback transaction involving any
Principal Property unless either (1) the Company or its Restricted Subsidiaries
would be entitled pursuant to the provisions described in

                                       12
<PAGE>

clauses (1) through (10) of the second paragraph of Section 501 of this
Supplemental Indenture to incur, issue, assume or guarantee indebtedness secured
by a Lien on such Principal Property without equally and ratably securing the
Notes then outstanding or (2) the Company or such Restricted Subsidiary shall
apply, or cause to be applied to the retirement of its secured debt within 120
days after the effective date of the sale and leaseback transaction, an amount
not less than the greater of (i) the net proceeds (net of all legal, title and
recording tax expenses, commissions and other fees and expenses incurred and all
federal, state, provincial, foreign and local taxes required to be paid or
accrued as a liability under GAAP, as a consequence of such sale) of the sale of
the Principal Property leased pursuant to such arrangement or (ii) the Fair
Market Value of the Principal Property so leased. This restriction will not
apply to a sale and leaseback transaction between the Company and a Restricted
Subsidiary or between Restricted Subsidiaries or involving the taking back of a
lease for a period of less than three years.

                  Notwithstanding the restrictions described above, the Company
or any Restricted Subsidiary may enter into a sale and leaseback transaction
provided, that at the time of such transaction, after giving effect thereto, the
Attributable Value thereof, together with all indebtedness secured by Liens
permitted pursuant to Section 501 of this Supplemental Indenture other than all
indebtedness secured by Liens permitted as described in clauses (1) through (10)
of the second paragraph of Section 501 of this Supplemental Indenture and other
than the Attributable Value of such sale and leaseback transactions permitted by
the preceding paragraph, does not exceed 15% of Consolidated Net Tangible Assets
of the Company.

Section 503.  Future Note Guarantors.

                  The Company will cause each Restricted Subsidiary that
Guarantees any Bank Indebtedness promptly to execute and deliver to the Trustee
a supplemental indenture substantially in the form set forth in Exhibit B to
this Supplemental Indenture pursuant to which such Restricted Subsidiary will
guarantee the Company's obligations under the Indenture and the Notes, in
accordance with and as further provided in Article VI of this Supplemental
Indenture.

Section 504.  Events of Default.

                  In addition to the Events of Default set forth in clauses (1),
(2) and (4) of Section 501 of the Base Indenture, any one of the following
events shall constitute an "Event of Default" hereunder and thereunder whenever
used with respect to the Notes in this Indenture (whatever the reason for such
Event of Default and whether it shall be voluntary or involuntary or be effected
by operation of law or pursuant to any judgment, decree or order of any court or
any order, rule or regulation of any administrative or governmental body):

               (i) a default by the Company in the payment of the Redemption
          Price with respect to any Note when such amount becomes due and
          payable;

               (ii) a default in the performance, or breach, by the Company of
          its obligations under Section 801 of the Base Indenture or Section 505
          of this Supplemental Indenture;

               (iii) a default in the performance, or breach, by the Company of
          its obligations under Sections 501 and 502 of this Supplemental
          Indenture, and continuance of such default or breach for a period of
          30 days after there has been given, by registered or

                                       13
<PAGE>

          certified mail, to the Company by the Trustee or to the Company and
          the Trustee by the Holders of at least 25% in aggregate principal
          amount of the Notes a written notice specifying such default or breach
          and requiring it to be remedied and stating that such notice is a
          "Notice of Default" hereunder, unless the Trustee, or the Trustee and
          the Holders of a principal amount of Notes of such series not less
          than the principal amount of Notes the Holders of which gave such
          notice, as the case may be, shall agree in writing to an extension of
          such period prior to its expiration;

               (iv) a default in the performance, or breach, by the Company of
          its other obligations under the Notes or this Supplemental Indenture,
          and continuance of such default or breach for a period of 90 days
          after there has been given, by registered or certified mail, to the
          Company by the Trustee or to the Company and the Trustee by the
          Holders of at least 25% in aggregate principal amount of the Notes a
          written notice specifying such default or breach and requiring it to
          be remedied and stating that such notice is a "Notice of Default"
          hereunder, unless the Trustee, or the Trustee and the Holders of a
          principal amount of Notes of such series not less than the principal
          amount of Notes the Holders of which gave such notice, as the case may
          be, shall agree in writing to an extension of such period prior to its
          expiration;

               (v) a failure to pay when due (subject to any applicable grace
          period) the principal of, or acceleration of, any Indebtedness for
          money borrowed by the Company or by any Restricted Subsidiary having
          an aggregate principal amount outstanding of at least $50.0 million,
          if in the case of any such failure, such Indebtedness has not been
          discharged or, in the case of any such acceleration, such acceleration
          has not been rescinded or annulled, in each case within 10 days after
          there has been given, by registered or certified mail, to the Company
          by the Trustee or to the Company and the Trustee by the Holders of at
          least 25% in aggregate principal amount of the Notes a written notice
          specifying such default or breach and requiring it to be remedied and
          stating that such notice is a "Notice of Default" hereunder;

               (vi) any final and nonappealable judgment or decree for the
          payment of money in excess (net of any amount covered by insurance) of
          $50.0 million against the Company or any Significant Subsidiary if (A)
          an enforcement proceeding thereon is commenced by any creditor or (B)
          it is not discharged, waived or stayed and remains outstanding for a
          period of 60 days;

               (vii) the entry by a court having jurisdiction in the premises of
          (A) a decree or order for relief in respect of the Company or any
          Restricted Subsidiary in an involuntary case or proceeding under any
          applicable Federal or State bankruptcy, insolvency, reorganization or
          other similar law or (B) a decree or order adjudging the Company or
          any Restricted Subsidiary a bankrupt or insolvent, or approving as
          properly filed a petition seeking reorganization, arrangement,
          adjustment or composition of or in respect of the Company or any
          Restricted Subsidiary under any applicable Federal or State law, or
          appointing a custodian, receiver, liquidator, assignee, trustee,
          sequestrator or other similar official of the Company or any
          Restricted Subsidiary or of any substantial part of its respective
          property, or ordering the winding up or liquidation of its affairs,
          and the

                                       14
<PAGE>

          continuance of any such decree or order for relief or any such other
          decree or order unstayed and in effect for a period of 60 consecutive
          days;

               (viii) the commencement by the Company or any Restricted
          Subsidiary of a voluntary case or proceeding under any applicable
          Federal or State bankruptcy, insolvency, reorganization or other
          similar law or of any other case or proceeding to be adjudicated a
          bankrupt or insolvent, or the consent by it to the entry of a decree
          or order for relief in respect of the Company or any Restricted
          Subsidiary in an involuntary case or proceeding under any applicable
          Federal or State bankruptcy, insolvency, reorganization or other
          similar law or to the commencement of any bankruptcy or insolvency
          case or proceeding against it, or the filing by it of a petition or
          answer or consent seeking reorganization or relief under any
          applicable Federal or State law, or the consent by it to the filing of
          such petition or to the appointment of or taking possession by a
          custodian, receiver, liquidator, assignee, trustee, sequestrator other
          similar official of the Company or any Restricted Subsidiary or of any
          substantial part of its respective property, or the making by it of an
          assignment for the benefit of creditors, or the admission by it in
          writing of its inability to pay its debts generally as they become
          due, or the taking of corporate action by the Company or any
          Restricted Subsidiary in furtherance of any such action; or

               (ix) any Note Guarantee ceasing to be in full force and effect or
          any Guarantor denying in writing that it has any liability under its
          Note Guarantee (other than by reason of the termination of the
          Indenture or the release of any such Note Guarantee in accordance with
          this Indenture).

Section 505.  Limitations on Consolidation, Etc.

                  The Company shall not consolidate with or merge into any other
Person or convey, transfer or lease its properties and assets substantially as
an entirety to any Person, and no Person shall consolidate with or merge into
the Company or convey, transfer or lease its properties or assets substantially
as an entirety to the Company unless, in addition to the conditions of Section
801 of the Base Indenture being met: (1) the resulting, surviving or transferee
Person (if other than the Company) is organized and existing under the laws of
the United States, any state thereof or the District of Columbia and shall
expressly assume, by an indenture supplemental hereto, executed and delivered to
the Trustee, in form satisfactory to the Trustee, the due and punctual payment
of the principal of (and premium, if any) and interest on all the Notes and the
performance of every covenant of this Indenture on the part of the Company to be
performed or observed; (2) immediately after giving effect to such transaction,
no Event of Default, and no event which, after notice of lapse of time would
become an Event of Default, or both, shall have occurred and be continuing; (3)
the Company shall deliver to the Trustee an Officers' Certificate and an Opinion
of Counsel, each stating that such consolidation, merger, conveyance or transfer
and, if a supplemental indenture is required in connection with such
transaction, such supplemental indenture comply with this Section 505 and that
all conditions precedent herein provided for relating to such transaction have
been complied with; and the Trustee, subject to Section 601 of the Base
Indenture, may rely upon such Officers' Certificate and Opinion of Counsel as
conclusive evidence that such transaction complies with this Section 505; and
(4) if, as a result of any such consolidation or merger or such conveyance,

                                       15
<PAGE>

transfer or lease, properties or assets of the Company would become subject to a
mortgage, pledge, lien, security interest or other encumbrance which would not
be permitted by Section 501 of this Supplemental Indenture, the Company or such
successor Person, as the case may be, shall take such steps as shall be
necessary effectively to secure the Notes equally and ratably with (or prior to)
all indebtedness secured thereby.

                                   Article VI

                               THE NOTE GUARANTEES

Section 601.  Unconditional Guarantee.

                  The Guarantors hereby agrees to be bound by all applicable
provisions of this Supplemental Indenture as a Guarantor and to guarantee the
Company's obligations under the Indenture and the Notes on the terms and subject
to the conditions set forth below:

                  (a) Each Guarantor hereby jointly and severally and fully and
unconditionally guarantees to each Holder of a Note, authenticated and delivered
by the Trustee and its successors and assigns, that: (1) the principal of, and
interest on the Notes will be duly and punctually paid in full when due, whether
at maturity, redemption or otherwise, and interest on the overdue principal and
(to the extent permitted by law) interest, if any, on the Notes and all other
obligations of the Company or the Guarantors to the Holders or the Trustee
hereunder and thereunder (including fees, expenses or other) and all other
Indenture Obligations will be promptly paid in full or performed, all in
accordance with the terms hereof; and (2) in case of any extension of time of
payment or renewal of any Notes or any of such other Indenture Obligations with
respect to the Notes, the same will be promptly paid in full when due in
accordance with the terms of the extension or renewal, whether at Stated
Maturity, by acceleration or otherwise. Failing payment when due of any amount
so guaranteed, or failing performance of any other Indenture Obligation of the
Company to the Holders of Notes, for whatever reason, each Guarantor will be
obligated to pay or cause the payment of, or to perform or cause the performance
of, the same immediately. An Event of Default under the Indenture or the Notes
shall constitute an event of default under this Note Guarantee, and shall
entitle the Holders of the Notes to accelerate the obligations of the Guarantor
hereunder in the same manner and to the same extent as the obligations of the
Company.

                  Each Guarantor hereby agrees that its obligations hereunder
shall be unconditional, irrespective of the validity, regularity or
enforceability of the Indenture, the Notes or the obligations of the Company or
any other Guarantor to the Holders or the Trustee hereunder or thereunder, the
absence of any action to enforce the same, any waiver or consent by any Holder
of Notes with respect to any provisions hereof or thereof, any release of any
other Guarantor, the recovery of any judgment against the Company, any action to
enforce the same, whether or not a Note Guarantee is affixed to any particular
Note, or any other circumstance which might otherwise constitute a legal or
equitable discharge or defense of a guarantor.

                  Each Guarantor hereby waives the benefit of diligence,
presentment, demand of payment, filing of claims with a court in the event of
insolvency or bankruptcy of the Company, any right to require a proceeding first
against the Company, protest, notice and all demands

                                       16
<PAGE>

whatsoever and covenants that (except as otherwise provided in Section 603 of
this Supplemental Indenture) its Note Guarantee will not be discharged except by
complete performance of the obligations contained in the Notes, the Indenture
and this Note Guarantee. This Note Guarantee is a guarantee of payment and not
of collection. Each Guarantor further agrees that, as between it, on the one
hand, and the Holders of Notes and the Trustee, on the other hand (1) subject to
this Article VI, the maturity of the obligations guaranteed hereby may be
accelerated as and to the extent provided in the Indenture for the purposes of
this Note Guarantee, notwithstanding any stay, injunction or other prohibition
preventing such acceleration in respect of the obligations guaranteed hereby,
and (2) in the event of any acceleration of such obligations as provided in the
Indenture, such obligations (whether or not due and payable) shall forthwith
become due and payable by such Guarantor for the purpose of this Note Guarantee.
Neither the Trustee nor any other Person shall have any obligation to enforce or
exhaust any rights or remedies or to take any other steps under any security for
the Indenture Obligations or against the Company or any other Person or any
property of the Company or any other Person before the Trustee is entitled to
demand payment and performance by any or all Guarantors of their liabilities and
obligations under their respective Note Guarantees or under the Indenture.

                  Until terminated in accordance with Section 603 of this
Supplemental Indenture, this Note Guarantee shall remain in full force and
effect and continue to be effective should any petition be filed by or against
the Company for liquidation or reorganization, should the Company become
insolvent or make an assignment for the benefit of creditors or should a
receiver or trustee be appointed for all or any significant part of the
Company's assets, and shall, to the fullest extent permitted by law, continue to
be effective or be reinstated, as the case may be, if at any time payment and
performance of the Notes are, pursuant to applicable law, rescinded or reduced
in amount, or must otherwise be restored or returned by any obligee on such
Notes, whether as a "voidable preference," "fraudulent transfer" or otherwise,
all as though such payment or performance had not been made. In the event that
any payment, or any part thereof, is rescinded, reduced, restored or returned,
the Notes shall, to the fullest extent permitted by law, be reinstated and
deemed reduced only by such amount paid and not so rescinded, reduced, restored
or returned.

                  (b) Each Guarantor that makes a payment or distribution under
this Note Guarantee shall have the right to seek contribution from any
non-paying Guarantor so long as the exercise of such right does not impair the
rights of the Holders under this Note Guarantee.

                  (c) Notwithstanding any of the foregoing, each Guarantor's
liability under this Note Guarantee shall be limited to the maximum amount that
would not result in this Note Guarantee constituting a fraudulent conveyance or
fraudulent transfer under applicable law.

                  (d) Each Guarantor acknowledges that it will receive direct
and indirect benefits from the financing arrangements contemplated by the
Indenture and that its Note Guarantee, and the waiver set forth in Section 604
of this Supplemental Indenture, is knowingly made in contemplation of such
benefits.

Section 602.  Additional Note Guarantors.

                                       17
<PAGE>

                  Each Restricted Subsidiary that is required to become a Note
Guarantor pursuant to Section 503 of this Supplemental Indenture shall promptly
execute and deliver to the Trustee a supplemental indenture substantially in the
form set forth in Exhibit B to this Supplemental Indenture, evidencing its Note
Guarantee on substantially the terms set forth in this Article VI. Concurrently
therewith, the Company shall deliver to the Trustee an Opinion of Counsel in
form and substance reasonably satisfactory to the Trustee to the effect that
such supplemental indenture has been duly authorized, executed and delivered by
such Restricted Subsidiary and that, subject to the applicable bankruptcy,
insolvency, fraudulent transfer, fraudulent conveyance, reorganization,
moratorium and other laws now or hereafter in effect affecting creditors' rights
or remedies generally and the general principles of equity, such supplemental
indenture is a valid and binding agreement of such Restricted Subsidiary,
enforceable against such Restricted Subsidiary in accordance with its terms.

Section 603.  Release of a Note Guarantee.

                  (a) Any Guarantor shall be automatically and unconditionally
released and discharged from all of its obligations under its Note Guarantee,
and such Note Guarantee shall terminate, at any such time that such Guarantor is
released and discharged from all of its obligations under all of its Guarantees
in respect of Bank Indebtedness, unless such release results from payment under
such Guarantee. Upon the delivery by the Company to the Trustee of an Officers'
Certificate and, if requested by the Trustee, an Opinion of Counsel to the
effect that the transaction giving rise to such release of such Note Guarantee
was made by the Company in accordance with the provisions of the Indenture and
the Notes, the Trustee shall execute any documents reasonably required in order
to evidence such release and discharge of such Guarantor from its obligations
under and termination of its Note Guarantee.

                  (b) Upon the sale, exchange or transfer to any Person not an
Affiliate of the Company of all of the Capital Stock held by the Company and its
Subsidiaries in, or all or substantially all the assets of, a Guarantor (which
sale, exchange or transfer is not prohibited by the Indenture), such Guarantor
shall be automatically and unconditionally released and discharged from all its
obligations under its Note Guarantee, and such Note Guarantee shall terminate.
Upon such occurrence, the Trustee shall execute any documents reasonably
required in order to evidence such release, discharge and termination in respect
of such Note Guarantee.

                  (c) Upon the release of any Guarantor from its Note Guarantee
pursuant to the provisions of the Indenture, each other Guarantor not so
released shall remain liable for the full amount of principal of, and premium,
if any, and interest on, the Notes as and to the extent provided in this Article
VI.

                  (d) Each Note Guarantee shall terminate and cease to be of
further effect upon satisfaction and discharge of the Indenture in accordance
with Section 401 of the Base Indenture.

Section 604.  Waiver of Subrogation.

                  Each Guarantor hereby irrevocably waives any claim or other
rights which it may now or hereafter acquire against the Company that arise from
the existence, payment, performance or enforcement of the Company's obligations
under the Notes and the Indenture or

                                       18
<PAGE>

such Guarantor's obligations under its Note Guarantee and the Indenture,
including, without limitation, any right of subrogation, reimbursement,
exoneration, indemnification, and any right to participate in any claim or
remedy of any Holder of Notes against the Company, whether or not such claim,
remedy or right arises in equity, or under contract, statute or common law,
until the Indenture is discharged and all of the Notes are discharged and paid
in full. If any amount shall be paid to any Guarantor in violation of the
preceding sentence and the Notes shall not have been paid in full, such amount
shall have been deemed to have been paid to such Guarantor for the benefit of,
and held in trust for the benefit of, the Holders of the Notes of such series,
and shall forthwith be paid to the Trustee for the benefit of such Holders to be
credited and applied upon such Notes, whether matured or unmatured, in
accordance with the terms of the Indenture.

Section 605.  Reliance on Judicial Order or Certificate of Liquidating Agent
              Regarding Dissolution.

                  Upon any payment or distribution of assets of any Guarantor
referred to in this Article VI, the Trustee, subject to the provisions of
Section 601 of the Base Indenture, and the Holders of Notes shall be entitled to
rely upon any order or decree entered by any court of competent jurisdiction in
which such insolvency, bankruptcy, receivership, liquidation, reorganization,
dissolution, winding-up or similar case or proceeding is pending, or a
certificate of the trustee in bankruptcy, receiver, liquidating trustee,
custodian, assignee for the benefit of creditors, agent or other Person making
such payment or distribution, delivered to the Trustee or to such Holders, for
the purpose of ascertaining the Persons entitled to participate in such payment
or distribution, the holders of other Indebtedness of such Guarantor, the amount
thereof or payable thereon, the amount or amounts paid or distributed thereon
and all other facts pertinent thereto or to this Article VI.

Section 606.  Article VI Applicable to Paying Agents.

                  In case at any time any Paying Agent other than the Trustee
shall have been appointed by the Company and be then acting hereunder, the term
`Trustee' as used in this Article VI shall in such case (unless the context
otherwise requires) be construed as extending to and including such Paying Agent
within its meaning as fully for all intents and purposes as if such Paying Agent
were named in this Article VI in addition to or in place of the Trustee.

Section 607.  No Suspension of Remedies.

                  Nothing contained in this Article VI shall limit the right of
the Trustee or the Holders of Notes to take any action to accelerate the
maturity of such Notes pursuant to the Indenture or to pursue any rights or
remedies hereunder or under applicable law.

                                   Article VII

                             SUPPLEMENTAL INDENTURES

Section 701.  Supplemental Indentures with Consent of Holders.

                                       19
<PAGE>

                  The terms of this Supplemental Indenture may be modified as
set forth in Article IX of the Base Indenture, provided that no supplemental
indenture shall, without the consent of the Holder of each Outstanding Note
affected thereby reduce the Redemption Price of any Note.

                                  Article VIII

                                  MISCELLANEOUS

Section 801.  Sinking Funds.

                  Article XII of the Base Indenture shall have no application.
The Notes shall not have the benefit of a sinking fund.

Section 802.  Confirmation of Indenture.

                  The Base Indenture, as supplemented and amended by this
Supplemental Indenture and all other indentures supplemental thereto, is in all
respects ratified and confirmed, and the Base Indenture, this Supplemental
Indenture and all indentures supplemental thereto shall be read, taken and
construed as one and the same instrument.

Section 803.  Counterparts.

                  The parties hereto may sign one or more copies of this
Supplemental Indenture in counterparts, all of which together shall constitute
one and the same agreement.

Section 804.  Governing Law.

                  THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY AND CONSTRUED
IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK (WITHOUT GIVING EFFECT TO
THE CONFLICT OF LAWS PRINCIPLES THEREOF).

                                       20
<PAGE>

                  IN WITNESS WHEREOF, the parties hereto have caused this
Supplemental Indenture to be duly executed as of the day and year first written
above.

                                                BECKMAN COULTER, INC., as issuer

                                                By:
                                                   -----------------------------
                                                   Name:
                                                   Title:

Attest:
         -----------------------------------------
         Name:
         Title:

                                       21
<PAGE>

                                                      CITIBANK, N.A., as Trustee

                                                      By:
                                                         -----------------------
                                                         Name:
                                                         Title:

Attest:
         --------------------------------
         Name:
         Title:

                                       22
<PAGE>

                                               COULTER CORPORATION, as Guarantor

                                               By:
                                                  ------------------------------
                                                  Name:
                                                  Title:

Attest:
         --------------------------------
         Name:
         Title:

                                               HYBRITECH INCORPORATED, as
                                                 Guarantor

                                               By:
                                                  ------------------------------
                                                  Name:
                                                  Title:

Attest:
         --------------------------------
         Name:
         Title:

                                       23
<PAGE>

                                    EXHIBIT A
                                  FORM OF NOTE

                  THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE
INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY
OR A NOMINEE THEREOF. THIS SECURITY MAY NOT BE EXCHANGED IN WHOLE OR IN PART FOR
A SECURITY REGISTERED, AND NO TRANSFER OF THIS SECURITY IN WHOLE OR IN PART MAY
BE REGISTERED, IN THE NAME OF ANY PERSON OTHER THAN SUCH DEPOSITARY OR A NOMINEE
THEREOF, EXCEPT IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE.

                  UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY ("DTC"), A NEW YORK CORPORATION,
TO THE ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT,
AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH
OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY
PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN
AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR
VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL IN AS MUCH AS THE REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

                                       A-1
<PAGE>

                              BECKMAN COULTER, INC.
                             o% Senior Note Due 2011

CUSIP No. o                                       $___________ Principal Amount
No. ____
Issue Date: November ____, 2001

                  Beckman Coulter, Inc., a corporation duly organized and
existing under the laws of the State of Delaware (herein called the "Company,"
which term includes any successor Person under the Indenture hereinafter
referred to), for value received, hereby promises to pay to Cede & Co., or
registered assigns, the principal sum of __________ Dollars on
___________________ , and to pay interest thereon from        or from the most
recent Interest Payment Date to which interest has been paid or duly provided
for, semi-annually in arrears on May        and November        in each year,
commencing May       , 2002 at the rate of         % per annum, until the
principal hereof is paid or made available for payment. The interest so payable,
and punctually paid or duly provided for, on any Interest Payment Date will, as
provided in such Indenture, be paid to the Person in whose name this Note (or
one or more Predecessor Securities) is registered at the close of business on
the Regular Record Date for such interest, which shall be       or (whether or
not a Business Day), as the case may be, next preceding such Interest Payment
Date. Any such interest not so punctually paid or duly provided for will
forthwith cease to be payable to the Holder on such Regular Record Date and may
either be paid to the Person in whose name this Note (or one or more Predecessor
Securities) is registered at the close of business on a Special Record Date for
the payment of such Defaulted Interest to be fixed by the Trustee, notice
whereof shall be given to Holders of Notes of this series not less than 10 days
prior to such Special Record Date, or be paid at any time in any other lawful
manner not inconsistent with the requirements of any securities exchange on
which the Notes of this series may be listed, and upon such notice as may be
required by such exchange, all as more fully provided in said Indenture.

                  Payment of the principal of and interest on this Note will be
made at the office or agency of the Company maintained for that purpose in The
Borough of Manhattan, The City of New York, in such coin or currency of the
United States of America as at the time of payment is legal tender for payment
of public and private debts; provided, however, that at the option of the
Company payment of interest may be made by check mailed to the address of the
Person entitled thereto as such address shall appear in the Security Register.

                  Reference is hereby made to the further provisions of this
Note set forth on the reverse hereof, which further provisions shall for all
purposes have the same effect as if set forth at this place.

                  Unless the certificate of authentication hereon has been
executed by the Trustee referred to on the reverse hereof by manual signature,
this Note shall not be entitled to any benefit under the Indenture or be valid
or obligatory for any purpose.

                                       A-2
<PAGE>

                  IN WITNESS WHEREOF, the Company has caused this instrument to
be duly executed.

                  Dated as of Date of Authentication:

                                              BECKMAN COULTER, INC.

                                              By:
                                                 -------------------------------
                                                 Name:
                                                      --------------------------
                                                 Title:
                                                       -------------------------

Attest:
         ------------------------------------
         Name:
         Title:

CITIBANK, N.A., as Trustee, certifies that this is one of the Notes referred to
in the Indenture.

Dated:

By:
     ----------------------------------------
     Authorized Signatory

                                       A-3
<PAGE>

The undersigned Guarantors each hereby agree, jointly and severally with all
other Guarantors and fully and unconditionally, to guarantee the Company's
obligations under the Indenture and the Notes on the terms and subject to the
conditions set forth in Article VI of the Supplemental Indenture.

                                    COULTER CORPORATION, as Guarantor

                                    By:
                                        ----------------------------------------
                                        Name:
                                             -----------------------------------
                                        Title:
                                              ----------------------------------

Attest:
         -----------------------------------------
         Name:
         Title:

                                    HYBRITEC INCORPORATED, as Guarantor

                                    By:
                                        ----------------------------------------
                                        Name:
                                             -----------------------------------
                                        Title:
                                              ----------------------------------

Attest:
         -----------------------------------------
         Name:
         Title:

                                       A-4
<PAGE>

                  This Note is one of a duly authorized issue of o% Senior Notes
Due 2011 of the Company (herein called the "Notes"), issued under a Senior
Indenture, dated as of April 25, 2001 (herein called the "Base Indenture"), as
supplemented by the First Supplemental Indenture, dated as of November o, 2001
(herein called the "Supplemental Indenture" and, together with the Base
Indenture, the "Indenture"), among the Company, as issuer, the Guarantors, as
guarantors, and Citibank, N.A., as Trustee (herein called the "Trustee," which
term includes any successor trustee under the Indenture), and reference is
hereby made to the Indenture and for a statement of the respective rights,
limitations of rights, duties and immunities thereunder of the Company, the
Trustee and the Holders of the Notes and of the terms upon which the Notes are,
and are to be, authenticated and delivered. This Note is one of the series
designated on the face hereof, limited in aggregate principal amount to $      ,
subject to increase as provided in the Indenture.

                  This Note is entitled to the benefits of the certain senior
Note Guarantees of the Guarantors and may thereafter be entitled to certain
other senior Note Guarantees made for the benefit of the Holders. Reference is
made to Article VI of the Supplemental Indenture and to the Note Guarantees for
terms relating to such Note Guarantees.

                  The Notes will be redeemable, in whole or in part, at the
option of the Company at any time at a redemption price equal to the greater of
(i) 100% of the principal amount of such Notes or (ii) the sum of the present
values of the remaining scheduled payments of principal and interest on the
Notes being redeemed on that Redemption Date (not including any portion of any
payments of interest accrued to the Redemption Date) discounted to the
Redemption Date on a semiannual basis at the Treasury Rate, as determined by the
Reference Treasury Dealer, plus         basis points; plus, in each case,
accrued and unpaid interest on the Notes to the Redemption Date, all as provide
in the Indenture.

                  In the event of redemption of this Note in part only, a new
Note or Notes of this series and of like tenor for the unredeemed portion hereof
will be issued in the name of the Holder hereof upon the cancellation hereof.

                  The Notes will not be entitled to the benefit of a sinking
fund.

                  The Indenture contains provisions for defeasance at any time
of the entire indebtedness of this Note or certain restrictive covenants and
certain Events of Default with respect to this Note, in each case upon
compliance with certain conditions set forth in the Indenture.

                  If an Event of Default with respect to Notes of this series
shall occur and be continuing, the principal of the Notes of this series may be
declared due and payable in the manner and with the effect provided in the
Indenture.

                  The Indenture permits, with certain exceptions as therein
provided, the amendment thereof and the modification of the rights and
obligations of the Company and the rights of the Holders of the Notes of each
series to be affected under the Indenture at any time by the Company and the
Trustee with the consent of the Holders of at least a majority in principal
amount of the Notes at the time Outstanding of each series to be affected. The
Indenture also contains provisions permitting the Holders of specified
percentages in principal amount of the

                                      A-5
<PAGE>

Notes of each series at the time Outstanding, on behalf of the Holders of all
Notes of such series, to waive compliance by the Company with certain provisions
of the Indenture and certain past defaults under the Indenture and their
consequences. Any such consent or waiver by the Holder of this Note shall be
conclusive and binding upon such Holder and upon all future Holders of this Note
and of any Note issued upon the registration of transfer hereof or in exchange
herefor or in lieu hereof, whether or not notation of such consent or waiver is
made upon this Note.

                  As provided in and subject to the provisions of the Indenture,
the Holder of this Note shall not have the right to institute any proceeding
with respect to the Indenture or for the appointment of a receiver or trustee or
for any other remedy thereunder, unless such Holder shall have previously given
the Trustee written notice of a continuing Event of Default with respect to the
Notes of this series, the Holders of not less than 25% in principal amount of
the Notes of this series at the time Outstanding shall have made written request
to the Trustee to institute proceedings in respect of such Event of Default as
Trustee and offered the Trustee reasonable indemnity, and the Trustee shall not
have received from the Holders of a majority in principal amount of Notes of
this series at the time Outstanding a direction inconsistent with such request,
and shall have failed to institute any such proceeding, for 60 days after
receipt of such notice, request and offer of indemnity. The foregoing shall not
apply to any suit instituted by the Holder of this Note for the enforcement of
any payment of principal hereof or any premium or interest hereon on or after
the respective due dates expressed herein.

                  As provided in the Indenture and subject to certain
limitations therein set forth, the transfer of this Note is registrable in the
Security Register, upon surrender of this Note for registration of transfer at
the office or agency of the Company in any place where the principal of and
interest on this Note are payable, duly endorsed by, or accompanied by a written
instrument of transfer in form satisfactory to the Company and the Security
Registrar duly executed by, the Holder hereof or his attorney duly authorized in
writing, and thereupon one or more new Notes of this series and of like tenor,
of authorized denominations and for the same aggregate principal amount, will be
issued to the designated transferee or transferees.

                  The Notes are issuable only in registered form without coupons
in denominations of $1,000.00 and any integral multiple thereof. As provided in
the Indenture and subject to certain limitations therein set forth, Notes are
exchangeable for a like aggregate principal amount of Notes of like tenor of a
different authorized denomination, as requested by the Holder surrendering the
same.

                  No service charge shall be made for any such registration of
transfer or exchange, but the Company may require payment of a sum sufficient to
cover any tax or other governmental charge payable in connection therewith

                  Prior to due presentment of this Note for registration of
transfer, the Company, the Trustee and any agent of the Company or the Trustee
may treat the Person in whose name this Note is registered as the owner hereof
for all purposes, whether or not this Note be overdue, and neither the Company,
the Trustee nor any such agent shall be affected by notice to the contrary.

                                      A-6
<PAGE>

                  THIS NOTE SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE
WITH THE LAWS OF THE STATE OF NEW YORK (WITHOUT GIVING EFFECT TO THE CONFLICT OF
LAWS PRINCIPLES THEREOF.)

                  All terms used in this Note that are defined in the Indenture
shall have the meanings assigned to them in the Indenture.

                                      A-7
<PAGE>

                                    EXHIBIT B

           FORM OF SUPPLEMENTAL INDENTURE IN RESPECT OF NOTE GUARANTEE

                  This Supplemental Indenture, dated as of __________ (this
"Supplemental Indenture"), among [name of New Guarantor] (the "New Guarantor"),
Beckman Coulter, Inc. (the "Company"), each other now existing Guarantor under,
and as defined in, the Indenture referred to below, and Citibank, N.A., as
trustee under the Indenture referred to below (the "Trustee").

                              W I T N E S S E T H:

                  WHEREAS, the Company and the Trustee have heretofore become
parties to a Senior Indenture, dated as of April 25, 2001 (the "Base
Indenture"), as supplemented by the First Supplemental Indenture, dated as of
November ___, 2001 (the "First Supplemental Indenture" and, together with the
Base Indenture and as amended, supplemented, waived or otherwise modified, the
"Indenture"), among the Company, as issuer, the now existing Guarantors, as
guarantors, and Citibank, N.A., as Trustee (herein called the "Trustee," which
term includes any successor trustee under the Indenture), providing for the
issuance of $_____________ aggregate principal amount of the Company's        %
Senior Notes Due 2011 (the "Notes");

                  WHEREAS, Sections 503 and 602 of the First Supplemental
Indenture provide that under certain circumstances the Company is required to
cause the New Guarantor to execute and deliver to the Trustee a supplemental
indenture pursuant to which the New Guarantor shall guarantee the Company's
obligations under the Notes pursuant to a Note Guarantee on the terms and
conditions set forth herein and in Article VI of the First Supplemental
Indenture; and

                  WHEREAS, pursuant to Section 901 of the Base Indenture, the
parties hereto are authorized to execute and deliver this Supplemental Indenture
to amend the Indenture, without the consent of any Holder;

                  NOW, THEREFORE, in consideration of the foregoing and for
other good and valuable consideration, the receipt of which is hereby
acknowledged, the New Guarantor, the Company, the other Guarantors and the
Trustee mutually covenant and agree for the benefit of the Holders of the Notes
as follows:

                  1.  Defined Terms. As used in this Supplemental Indenture,
                      terms defined in the Indenture or in the preamble or
                      recital hereto are used herein as therein defined. The
                      words "herein," "hereof" and "hereby" and other words of
                      similar import used in this Supplemental Indenture refer
                      to this Supplemental Indenture as a whole and not to any
                      particular section hereof.

                  2.  Agreement to Guarantee. The New Guarantor hereby agrees,
                      jointly and severally with all other Guarantors and fully
                      and unconditionally, to guarantee the Company's
                      obligations under the Indenture and the Notes on the terms
                      and subject to the conditions set forth in Article VI of
                      the Supplemental Indenture and to be bound by all other
                      applicable provisions of the Indenture as a Guarantor.

                                      B-1
<PAGE>

                  3.  Termination, Release and Discharge. The New Guarantor's
                      Note Guarantee shall terminate and be of no further force
                      or effect, and the New Guarantor shall be released and
                      discharged from all obligations in respect of such Note
                      Guarantee, as and when provided in Section 603 of the
                      First Supplemental Indenture.

                  4.  Parties. Nothing in this Supplemental Indenture is
                      intended or shall be construed to give any Person, other
                      than the Holders and the Trustee, any legal or equitable
                      right, remedy or claim under or in respect of the New
                      Guarantor's Note Guarantee or any provision contained
                      herein or in Article Thirteen of the Indenture.

                  5.  Governing Law.  THIS SUPPLEMENTAL INDENTURE SHALL BE
                      GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF
                      THE STATE OF NEW YORK (WITHOUT GIVING EFFECT TO THE
                      CONFLICT OF LAWS PRINCIPLES THEREOF).

                  6.  Ratification of Indenture; Supplemental Indentures Part of
                      Indenture. Except as expressly amended hereby, the
                      Indenture is in all respects ratified and confirmed and
                      all the terms, conditions and provisions thereof shall
                      remain in full force and effect. This Supplemental
                      Indenture shall form a part of the Indenture for all
                      purposes, and every Holder of Notes heretofore or
                      hereafter authenticated and delivered shall be bound
                      hereby. The Trustee makes no representation or warranty as
                      to the validity or sufficiency of this Supplemental
                      Indenture.

                  7.  Counterparts.  The parties hereto may sign one or more
                      copies of this Supplemental Indenture in counterparts,
                      all of which together shall constitute one and the same
                      agreement.

                  8.  Headings.  The section headings herein are for
                      convenience of reference only and shall not be deemed to
                      alter or affect the meaning or interpretation of any
                      provisions hereof.

                                      B-2
<PAGE>

                  IN WITNESS WHEREOF, the parties hereto have caused this
Supplemental Indenture to be duly executed as of the date first above written.

                       [NAME OF NEW GUARANTOR],

                       By:
                           ----------------------------------------
                           Name:
                           Title:
                           Address:

                       BECKMAN COULTER INC.

                       By:
                          -----------------------------------------
                           Name:
                           Title:

                       [Add signature block for any other
                        existing Guarantor]

                       [TRUSTEE]

                       By:
                          -----------------------------------------
                           Name:
                           Title:

                                      B-3

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