EXHIBIT 10.45

5








                                                ONE MEMORIAL DRIVE
                                             CAMBRIDGE, MASSACHUSETTS




                                            AMENDED AND RESTATED LEASE


                                            dated as of January 1, 1998


                                                  By and Between


                                      ONE MEMORIAL DRIVE LIMITED PARTNERSHIP


                                                        and


                                      PUTNAM, HAYES & BARTLETT, INCORPORATED




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                                                 TABLE OF CONTENTS

                                                                            Page

ARTICLE I

             REFERENCE DATA ...................................................1
                           1.1 Subjects referred to............................1
                           1.2 Exhibits .......................................3

ARTICLE II

             PREMISES AND TERM ................................................3
                       2.1 Premises .........................................  3
                       2.2 Common Facilities ..................................4
                       2.3 Landlord's Reservations ............................4
                       2.4 Term ...............................................4
                       2.5 Additional Terms ...................................4
                       2.6 Determination of Fair Rental Value..................5

ARTICLE III

             CONSTRUCTION.......5
                       3.1 Intention Ily Deleted ..............................5
                    3.2 Tenant Changes and Additions ..........................5
                       3.3 Landlord's Construction Contribution ...............7
                       3.4 General Provisions Applicable to Construction ......8
                       3.5 Construction Representatives .......................8

ARTICLE IV

            RENT  .............................................................8

                       4.1 Fixed Rent .........................................8
                       4.2 Additional Rent ....................................9

ARTICLE V

             LANDLORD'S COVENANTS ...........................................15
                           5.1 Landlord's Covenants .........................15
                           5.2 Interruptions ................................15





ARTICLE VI

             TENANT'S COVENANTS ..............................................16
                           6.1 Tenant's Covenants ............................16
ARTICLE VII

             CASUALTY AND TAKING .............................................22
                           7.1 Casualty and Taking ...........................22
                           7.2 Reservation of Award ..........................24

ARTICLE VIII

             RIGHTS OF MORTGAGE ..............................................24

                       8.1 Superiority of Leas ...............................24
                       8.2 No Prepayment Payment ............................25
                       8.3 No Release or Termination ........................25
                       8.4 No Modification, et ..............................26
                       8.5 Continuing Offer .................................26
                       8.6 Subordination ....................................26
                       8.7 Implementation ...................................26

ARTICLE IX

             DEFAULTS........................................................27
                           9.1Events of Default .............................27
                           9.2 Remedies .....................................28

ARTICLE X

             MISCELLANEOUS ..................................................29
                           10.1 Intentionally Deleted .......................29
                           10.2 Titles ......................................29
                           10.3 Notice of Lease .............................30
                           10.4 Holding Over ................................30
                           10.5 Notice .....................................30
                           10.6 Bind and Inure ..............................30
                           10.7 No Surrender ................................31
                           10.8 No Waiver, Etc ..............................31
                           10.9 No Accord and Satisfaction ..................31
                           10.10 Cumulative Remedies ........................31
                           10.11 Partial Invalidity and Applicable Law ......32
                           10.12 Landlord's Right to Cure Tenant's Default ..32
                           10.13 Estoppel Certificates ......................32
                           10.14 Waiver of Subrogation ............          33
                           10.15 Brokerage ...........................       33
                           10.16 Force Majeure .......................       33
                           10.17 Authority ...........................       34
                           10.18 Parking .............................       34
                           10.19 Building Directory ..................       34
                           10.20 Tenant's Right to Cure ..............       35
                           10.21 Certain Other Matters ...............       35
                           10.22 Prior Lease .........................       36





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                                                ONE MEMORIAL DRIVE
                                             CAMBRIDGE, MASSACHUSETTS

                                            AMENDED AND RESTATED LEASE

                                            dated as of January 1, 1998


                                                     ARTICLE I

                                                  REFERENCE DATA

         1.1......Subjects referred to:

         Each reference in this Amended and Restated Lease (this "Lease") to any
of the following  subjects shall be construed to incorporate the data stated for
that subject in this Section 1. 1:

          Landlord:.........   One  Memorial   Drive  Limited   Partnership,   a
          Massachusetts limited partnership

Original Address
of Landlord:......                  One Memorial Drive
         .........                  Cambridge, Massachusetts 02142

Landlord's
Construction
Representative:...         Karen A. Stitt

Tenant:  .........         Putnam, Hayes & Bartlett, Incorporated

Original Address of
Tenant:  .........         One Memorial Drive
         .........                  Cambridge, Massachusetts 02142

Tenant's
Construction
Representative:...         Barbara J. Levine

          Tenant's Space: 55,763 rentable square feet ("p.s.f.") of the building
          (the "Building")  located on the land more  particularly  described in
          Exhibit A attached  hereto  consisting of 21,422  p.s.f.  on Floor 15;
          20,986 p.s.f.  on Floor 16; and 13,355 p.s.f.  on Floor 17. As used in
          this Lease,  all p.s.f.  figures include  proportionate  shares of all
          common areas of the  Building.  A plan showing the Tenant's  Space the
          "Premises") is attached hereto as Exhibit B.
Total Rentable
Floor Area of the
Building:.........                  351,680 p.s.f.

Term:    .........                  Eleven (11) years, eleven (11) months.

Term Commencement
Date:    .........                  January 1, 1998.

Rent Commencement
Date:    .........                  January 1, 1998.

Term Expiration Date:      November 30, 2009.

Annual Fixed Rent: See chart below:

Rental Period.....         Annual Base Rent Monthly Base Rent P/S/F

1/1/98 - 11/30/99    $2,230,520.00             $185,876.77                $40.00

12/1/99 - 11/30/04   $2,174,757.00             $181,229.75                $39.00

12/1/04 - 11/30/09   $2,453,572.00             $204,464.33                $44.00


          Extension  Options:  Tenant may elect to extend the Term hereof for up
          to two (2)  Additional  Terms of five (5) years  each,  subject to the
          provisions of Section 2.5.

Tenant's Included
Share of Real
Estate Taxes:                       
(i) For the period commencing on January 1, 1998 and continuing
through November 30, 1999, $3.00 per p.s.f. of the Premises.

          (ii) For the period  commencing  on  December  1, 1999 and  continuing
          through November 30, 2009, $5.50 per p.s.f. of the Premises.

Tenant's Included
Share of Operating
          Expenses:  (i) For the  period  commencing  on  January  1,  1998  and
          continuing through November 30, 1999, $4.50 p.s.f. of the Premises.


                                    (ii) For the period  commencing  on December
                                    1, 1999 and continuing  through November 30,
                                    2009, $5.60 per p.s.f. of the Premises.

Permitted Uses:            General business office use.

          Parking  Spaces:  As provided in Section  10.18,  up to fifty-six (56)
          spaces in the garage  serving the  Building.  The monthly fee for each
          such  parking  space  shall be at such  rates as shall be set forth in
          Section 10. 18.

         1.2      Exhibits.

         The Exhibits listed below in this section are incorporated in the Lease
by reference and are to be construed as part of this Lease:

Exhibit A         -        Legal Description of the Land.
Exhibit B         -        Plan Showing Tenant's Space.
Exhibit C         -        Determination of Fair Rental Value
Exhibit D         -        Intentionally Deleted.
Exhibit E         -        Intentionally Deleted.
Exhibit F         -        Intentionally Deleted.
Exhibit G         -        Landlord's Services.
Exhibit H         -        Rules and Regulations.



                                                    ARTICLE II

                                                 PREMISES AND TERM

         2.1      Premises.

         Landlord  hereby  leases  to  Tenant,  and  Tenant  hereby  hires  from
Landlord,  for the Term,  subject to and with the benefit of the  provisions  of
this Lease,  Tenant's Space in the building (the "Building") located on the land
described in Exhibit A attached  hereto,  excluding  exterior  faces of exterior
walls,  the common  stairways,  stairwells,  elevators and elevator  wells,  and
pipes, ducts, conduits,  wire and appurtenant fixtures serving exclusively or in
common other parts of the Building, and if Tenant's Space includes less than the
entire  rentable  area of any floor,  excluding  the  central  core area of such
floor.  Tenant's Space, with said exclusions,  is hereinafter sometimes referred
to as the "Premises".

         2.2      Common Facilities.

         Tenant shall have, as appurtenant to the Premises,  the right to use in
common with others entitled thereto,  subject to rules of general  applicability
to tenants of the Building from time to time made by Landlord of which Tenant is
given notice:  (a) the common facilities in the Building or on the land on which
it is located (the  "Land"),  including  common  walkways,  driveways,  lobbies,
hallways,  ramps,  stairways,  elevators and loading  platforms;  (b) the common
pipes, ducts,  conduits,  wires and appurtenant  equipment serving the Premises;
and (c) if the Premises include less than the entire rentable area of any floor,
the common toilets and other common facilities.

         2.3      Landlord's Reservations.

Upon reasonable  prior notice (except in the event of emergency  constituting an
imminent threat to persons or property),  Landlord  reserves the right from time
to time,  without  unreasonable  interference  with Tenant's  Permitted Uses, to
install, repair, replace, use, maintain and relocate for service to the Premises
and  to  other  parts  of  the  Building,  pipes,  ducts,  conduits,  wires  and
appurtenant fixtures wherever located in the Building,  and to alter or relocate
any other common facility,  provided that the  substitutions  are  substantially
equivalent or better. Installations, replacements and relocations referred to in
this  Section  2.3 shall be located in the  central  core  area,  above  ceiling
surfaces,  below floor surfaces or within the perimeter walls of the Premises to
the extent  practicable,  and in all events shall not materially reduce rentable
area or floor to ceiling  height.  Except to the extent required by emergencies,
Landlord will use reasonable  efforts to perform all such work at such times and
in such  manner as will  minimize  any  disruption  of the  conduct of  Tenant's
business.

         2.4      Term.

         To have  and to hold the  Premises  for a  period  commencing  with the
Commencement  Date,  and  continuing  for the Term unless  sooner  terminated as
provided elsewhere in this Lease.

         2.5      Additional Terms.

         Provided that Tenant is not then in default after any applicable  grace
periods (a) in the payment of the Annual Fixed Rent, or Additional  Rent, or (b)
of any other obligation of Tenant under this Lease,  pursuant to any outstanding
notice  thereof  referred  to in  Section 9. 1,  Tenant  shall have the right to
extend the Term  hereof for up to two (2)  successive  periods of five (5) years
each,  such  options to extend to be exercised by the giving of notice by Tenant
to Landlord at least  twelve (12)  months  prior to the  expiration  of the then
current  term.  Upon the  giving of each such  notice,  this  Lease and the Term
hereof shall be extended,  for an additional term of five (5) years, without the
necessity for the execution of any additional documents.  Time is of the essence
in the giving of such notice.  In no event shall the Term hereof be extended for
more than ten (10) years after the  expiration  of the Initial  Term,  nor shall
Tenant have the right to exercise  succeeding  extension  options  unless it has
duly and validly  exercised  the extension  option next  preceding the extension
option being currently exercised by Tenant. The Extension Term shall be upon all
the terms,  conditions and provisions of this Lease except that the Annual Fixed
Rent during each of the Extension  Terms shall be ninety-five  percent (95 %) of
the Fair  Rental  Value (as  agreed  between  the  parties or as  determined  by
appraisal  of the Premises for such  Extension  Term,  but in no event less than
$44.00 p.s.f.  for all floors,  which, if not agreed upon by Landlord and Tenant
within three (3) months of the date on which the applicable Extension Term is to
commence,  shall  be  determined  by  appraisal  as  provided  in  Section  2.7.
Notwithstanding  the foregoing,  Tenant may advance said three (3) months period
to a fifteen  (15) month  period upon  written  notice to Landlord  prior to the
commencement  of such fifteen (15) month period to the end that any rental to be
determined  by  appraisal  shall have been  determined  and made known to Tenant
prior to the  last  date on which  Tenant  is  required  to give  notice  of its
intention to exercise its next arising extension option. For purposes of Section
2.7,  the day  following  expiration  of the  Original  Term  or an  immediately
preceding Extension Term shall be deemed the relevant Available Date.

         2.6      Determination of Fair Rental Value.

         In the  event  the  Fair  Rental  Value  of  the  Premises  during  any
Additional  Term must be  determined  by appraisal,  the  determination  of Fair
Rental Value shall be made as provided in Exhibit C hereto.


                                                    ARTICLE III

                                                   CONSTRUCTION

         3.1      Intentionally Deleted.

3.2      Tenant Changes and Additions.

Tenant may, from time to time after  commencement  of the Term, make changes and
additions to the Premises in accordance with plans and  specifications  therefor
first approved by Landlord.  Non-structural  changes within the Premises costing
$25,000.00 or less in any one instance and aggregating no more than  $200,000.00
during  the  entire  term  hereof  may be made by  Tenant  without  the need for
Landlord's  approval;  however,  in any such instance  Tenant shall give written
notice  thereof to Landlord  prior to  commencing  any such change and otherwise
shall be bound by the remaining  provisions hereof.  Tenant shall have the right
to make  structural  changes to the  Premises  with the  written  consent of the
Landlord  which shall ,not be  unreasonably  withheld or delayed.  No structural
change of any nature may be made, however, if the same affects the appearance of
the Building aesthetically; is visible from outside the Building; materially and
adversely  affects the  operation of the Building or the rights of other tenants
thereof;  adversely  affects any structural  member of the Building;  and unless
notice  of such  intended  change  together  with a  complete  set of plans  and
specifications  therefor  is  delivered  to the  Landlord at least 30 days prior
commencement of the installation of such change.  Tenant may make non-structural
changes in excess of the above amounts upon receiving  Landlord's  prior written
consent,  which consent shall not be unreasonably  withheld or delayed.  Without
limiting  Landlord's  rights  to  disapprove  any such  changes  and  additions,
Landlord need not approve such plans and  specifications if the proposed changes
and additions will require significant expense to readapt the Premises to normal
office use on lease  termination  (unless Tenant pays such increased  costs), or
will  increase the cost of  insurance or taxes on the Building or of  Landlord's
services  called for by Section 5.1 or will violate any other  provision of this
Lease.   All  fixtures  and  all   paneling,   partitions,   railings  and  like
installations,  installed  in the  Premises at any time,  either by Tenant or by
Landlord  o n  Tenant's  behalf,  shall,  subject  to  Tenant's  right  to  make
alterations,  become the  property  of  Landlord  and shall  remain  upon and be
surrendered  with the Premises,  unless  Landlord  grants its  permission to the
removal of same,  within  twenty (20) days after the  receipt of written  notice
from  Tenant  requesting  such  permission.  Nothing  in this  Section  shall be
construed to prevent Tenant's removal of trade fixtures, but upon removal of any
such trade fixtures from the Premises or upon removal of other  installations as
may be required by Landlord, Tenant shall immediately and at its expense, repair
and restore the Premises to the condition  existing  prior to  installation  and
repair any damage to the  Premises  or the  Building  due to such  removal.  All
property  permitted  or  required to be removed by Tenant at the end of the term
remaining in the Premises after Tenant's  removal shall be deemed  abandoned and
may, at the election of Landlord,  either be retained as Landlord's  property or
may be removed  from the  Premises  by  Landlord  at  Tenant's  expense.  All of
Tenant's  changes  and  additions  shall be  coordinated  with  any  work  being
performed  by  Landlord  and in such  manner  as to  maintain  harmonious  labor
relations  and not to damage the  Building or Land or  interfere  with  Building
operation,  and  shall be  performed  by  Landlord's  general  contractor  or by
contractors  or workmen first  approved by Landlord  which approval shall not be
unreasonably  withheld or delayed.  Except  with  respect to work by  Landlord's
general  contractor,  Tenant,  before  its work is  started,  shall:  secure all
licenses and permits necessary therefor;  deliver to Landlord a statement of the
names of all its  contractors and  subcontractors  and the estimated cost of all
labor and  material to be  furnished  by them;  cause each  contractor  to carry
workmen's  compensation  insurance  in  statutory  amounts  covering  all of the
contractor's  and  subcontractor's   employees,   commercial  general  liability
insurance,  including broad form property damage and contractual  liability with
the following minimum limits:  general aggregate $2,000,000,  Products/completed
operations  aggregate  $2,000,000,   each  occurrence  $1,000,000,   personal  &
advertising  injury  $1,000,000  and  medical  payments  $5,000 per  person.  In
addition  Tenant  shall  cause  each  contractor  and   subcontractor  to  carry
employer's liability insurance covering bodily injury by disease with such limit
not less than  $1,000,000 for each person and a 1,000,000  policy limit,  bodily
injury by accident with limits of not less than $1,000,000; automobile liability
insurance with a combined single limit of not less than  $1,000,000  which shall
cover all owned, non-owned and hired motor vehicles which are operated on behalf
of the contractor and/or subcontractor,  and an umbrella/excess liability policy
with  minimum   limits  of  $5,000,000  in  the  aggregate  and  $5,000,000  per
occurrence.  All policies shall be written by companies  rated not less than A -
VIII by Best's  Insurance  Reports (all such insurance to name Landlord,  Tenant
and any mortgagee o f Landlord as additional  insureds) and contain a minimum of
thirty (30) days notice of  cancellation.  Tenant  shall  deliver or cause to be
delivered  to  Landlord   certificates  of  all  such  insurance  prior  to  the
commencement  of any work on the  Premises  and shall  provide  upon  Landlord's
request  certified  copies  of the  insurance  policies.  Tenant  agrees  to pay
promptly  when due the entire  cost of any work done on the  Premises  by, or on
behalf of Tenant,  and not to cause or permit  any liens for labor or  materials
performed or furnished in connection  therewith to attach to the  Premises,  the
Building or any interest of Landlord therein. Tenant agrees promptly upon notice
or  knowledge  thereof to  discharge  or bond over any such  liens  which may so
attach in  accordance  with  Section  6.1.13  hereof,  and  agrees to  indemnify
Landlord for, from and against any and all loss, cost or expense (including, but
not limited to, reasonable attorneys'. fees and costs) incurred by Landlord as a
result of Tenant's work. The payment by Landlord of Landlord's  Contribution (as
defined in Section 3.3 below) shall not be construed as a "cost or expense" from
which Tenant must indemnify Landlord pursuant to the preceding sentence.

         Each  contractor  and  subcontractor  must  agree in  their  respective
contracts  to  defend,   save,   indemnify  and  hold  harmless  Landlord,   its
subsidiaries,  officers,  agents and employees from any and all claims, demands,
damages, losses, costs, expenses,  judgements,  or liabilities arising out of or
resulting  from  the  relevant  contractor,   contractor's  employees,   agents,
performance  of its work in, on or about the Premises.  Such contracts must also
contain  a mutual  waiver  of  subrogation  to the  effect  that  the  Landlord,
contractors and subcontractors waive all rights against each other, any of their
agents and employees for damages caused by fire or any other perils covered by a
standard  special causes of loss form property  policy.  All property  insurance
policies shall contain a waiver of subrogation by endorsement or otherwise,  and
the aforesaid  contracts shall provide that Landlord agrees,  and the contractor
and its  subcontractors  will have agreed in their  contracts as aforesaid  that
property  insurance  represents the sole recourse for loss or damage to property
and each will have waived rights to recover for property damage from each other.

3.3 Landlord's Construction  Contribution.  Landlord agrees to pay up to the sum
of Six Hundred Thousand Dollars  ($600,000.00)  ("Landlord's  Contribution")  to
Tenant to reimburse  Tenant,  in part, for the cost of improvements  made to the
Premises  after the date  hereof,  including,  but not  limited  to,  soft costs
incurred such as architectural  design fees, other professional fees and cabling
costs.  Fifty  percent  (50%) (the  "First  Fifty  Percent")  of the  Landlord's
Contribution  shall be made  available to Tenant on or after January 1, 1998 and
must be  requisitioned by Tenant on or prior to December 31, 2000. The remaining
fifty percent (50%) (the "Second Fifty Percent") of the Landlord's  Contribution
shall be made  available  to  Tenant  on or after  December  1, 1999 and must be
requisitioned  by Tenant on or prior to December 31, 2003.  For the  overlapping
time period from  December 1, 1999 until  December 31, 2000,  Tenant shall first
requisition  contributions  available from the First Fifty  Percent,  but if the
First Fifty  Percent has been fully  requisitioned  by Tenant,  the Second Fifty
Percent shall be available to Tenant.  Each request for an advance of Landlord's
Contribution (a "Requisition")  submitted by Tenant to Landlord shall be made no
more frequently than once in any calendar month, shall bear the certification of
Tenant's  architect  as to the nature of the portion of the Tenant  Improvements
installed and the amount actually  disbursed by Tenant  thereagainst.  Each such
Requisition shall be accompanied by copies of partial lien waivers or final lien
waivers  (in  the  case of the  final  installment)  from  all  contractors  and
subcontractors,   shall  be  in  such   detail  and  contain   such   supporting
documentation  as  Landlord  reasonably  may require and shall be subject to the
approval of Landlord  and/or its  professional  consultants  acting  reasonably.
Within twenty-five (25) days of the receipt of each Requisition,  Landlord shall
disburse to Tenant a sum equal to ninety  percent  (90%) of the amount set forth
therein,  the remaining ten percent  (10%) of each  Requisition  to be disbursed
only upon full completion of the Tenant  Improvements with respect to which such
portions of Landlord's Contribution is being applied (including all "punch list"
items),  provided  that  Landlord  is  reasonably  satisfied  that  such  Tenant
Improvements  have been  constructed in accordance  with Tenant's Plans and upon
the  reasonable  satisfaction  of  Landlord  that no  mechanics  or other  liens
relating to such Tenant Improvements will thereafter arise against the Land, the
Building or the Premises. At Landlord's election, payments under any Requisition
may be made jointly to Tenant and  Tenant's  general  contractor  in such manner
(such as joint payees on a check),  as to require  acknowledgment  of receipt of
the amount of such payment by both parties.


         3.4      General Provisions Applicable to Construction.

         All construction  work required or permitted by this Lease,  whether by
Landlord  or by Tenant,  shall be done in a good and  workmanlike  manner and in
compliance with all applicable laws and all lawful  ordinances,  regulations and
orders of governmental  authority and insurance industry standards,  and meet or
exceed the building standard, as same may change from time to time.

         3.5      Construction Representatives.

         Each party authorizes the other to rely in connection with the original
design and  construction  upon a written  approval on the party's  behalf by any
Construction  Representative of the party named in Article I above or any person
hereafter designated in substitution or addition by notice to the party relying.


                                                    ARTICLE IV

                                                       RENT

         4.1      Fixed Rent.

         Tenant agrees to pay,  without any offset or deduction  whatever except
only,  to the  extent  applicable,  as  specifically  provided  pursuant  to the
provisions of Articles  III, V and VII hereof,  Annual Fixed Rent to Landlord at
the appropriate rate set forth in Section 1. 1 hereof, in equal  installments of
1/12th of the Annual  Fixed  Rent in  advance on the first day of each  calendar
month included in the Term, commencing on the Rent Commencement Date and for any
portion of a calendar  month at the  beginning or end of the Term,  at that rate
payable in advance for such portion.  Tenant shall pay all rent when due; and no
invoice  for rent due or to  become  due or  notice  of rent  past due  shall be
required.

         4.2      Additional Rent.

                  4.2.1    Taxes.

         Tenant shall pay to Landlord as additional rent a  proportionate  share
(as defined in Section  4.2.4) of all real  estate  taxes (as defined in Section
4.2.2)  imposed  against the  Building and the Land  attributable  to the period
commencing  twelve (12) months after the Term Commencement  Date,  prorated with
respect to any  portion of a fiscal year in which the first  anniversary  of the
Term of this  Lease  occurs or the Tenn  ends.  Such  payments  shall be due and
payable ten (10) days after notice is given to Tenant by Landlord,  which notice
is intended to be given during the period thirty (30) days just prior to the due
date of each half fiscal year's taxes.  If Landlord  shall receive any refund of
real estate taxes of which Tenant has paid a portion  pursuant to this  Section,
then, out of any balance remaining after deducting  Landlord's expenses incurred
in obtaining such refund,  Landlord  shall pay to Tenant the same  proportionate
share of said  balance,  prorated  as set forth  above.  Tenant  shall with each
monthly  installment  of Annual Fixed Rent,  make tax fund payments to Landlord.
The term "tax fund payments refers to such payments as Landlord shall reasonably
determine to be  sufficient  to provide in the aggregate a fund adequate to pay,
when they become due and payable,  all payments  required from Tenant under this
Section.  In the  event  that said tax fund  payments  are not  adequate  to pay
Tenant's  share of such taxes,  Tenant shall pay to Landlord the amount by which
such aggregate of tax fund payments is less than the amount of said share,  such
payment to be due and payable at the time set forth above.  Any surplus tax fund
payment to Landlord  shall be accounted  for to Tenant after payment by Landlord
of the taxes on  account  of which  they were  made,  and shall be  credited  by
Landlord  against future tax fund payments  except that if such surplus tax fund
payment exceeds $1,500.00,  it shall, on Tenant's demand, be refunded to Tenant.
If such surplus  fund  payment  exceeds the amount that should have been paid by
more than ten percent (10 %),  Landlord  shall pay to, or credit  Tenant (as the
case may be) with  interest on such surplus at an annual rate of interest  equal
to two  percent (2 %) greater  than the prime rate of  interest,  so-called,  of
BankBoston,  N.A.  in effect  at the time.  Subject  to the  provisions  of this
Section,  Landlord shall be responsible for payment of all real estate taxes (as
hereinabove  defined)  imposed against the Building and the Land. If the size of
the Building changes, the same shall be equitably reflected hereunder.

         4.2.2    Real Estate Taxes.

         The term "real estate  taxes" as used herein shall mean all real estate
taxes, assessments, and other governmental impositions and charges of every kind
and nature whatsoever not included in Operating Expenses,  extraordinary as well
as ordinary,  foreseen and unforeseen,  and each and every installment  thereof,
which shall or may during the Term as it may be extended be  assessed,  imposed,
become due and payable or be levied by the lawful taxing authorities against the
Land,   the  Building,   and  all  other   improvements   located  on  the  Land
(collectively,  the  "Property") or liens upon or arising in connection with the
use or occupancy or possession of, or becoming due or payable out of or for, the
Property or any part thereof,  including all costs and fees incurred by Landlord
in  contesting  same  or  in  negotiating  with  the  appropriate   governmental
authorities as to the same.  Betterments and other charges payable over a period
in excess of one year  shall  with the  interest  charges  thereon be treated as
being paid over the longest possible period.

         Except to the extent the same are generally considered to be in lieu of
real estate taxes,  nothing herein  contained shall be construed to include as a
real estate tax any inheritance,  estate, succession, transfer, gift, franchise,
corporation, income or profit tax or capital levy that is or may be imposed upon
Landlord;  provided,  however, that, if at any time during the Term as it may be
extended the methods of taxation  prevailing at the Term Commencement Date shall
be  altered so that in lieu of or as a  substitute  for the whole or any part of
the taxes now levied,  assessed or imposed,  there shall be levied,  assessed or
imposed  an income  or other  tax of  whatever  nature,  then the same  shall be
included in the computation of real estate taxes hereunder.

         Real estate  taxes shall  include  any  excise,  transaction,  sales or
privilege tax now or hereafter imposed by any government or governmental  agency
upon Landlord on account of, attributed to, or measured by rent or other charges
payable by Tenant, or levied by reason of the parking made available by Landlord
on the  Property,  and shall be repaid by Tenant to  Landlord in addition to and
together with the Rent and other charges otherwise payable hereunder;  provided,
that any tax levied by reason of the parking shall be apportioned so that Tenant
shall  reimburse  Landlord for that portion of such parking tax in proportion to
the  number of parking  spaces  provided  to Tenant  under  subparagraph  10. 18
hereof.


         4.2.3 Operating Expenses.

         Tenant shall pay to Landlord as additional rent a  proportionate  share
(as  defined in Section  4.2.4) of all costs and  expenses  incurred by Landlord
from  and  after  the  period  commencing  twelve  (12)  months  after  the Tenn
Commencement  Date in the operation and maintenance of the Building and the Land
in accordance with generally  accepted  operational  and maintenance  procedures
(but  applied  in  a  manner  consistent  with  generally  accepted   accounting
principals consistently applied),  including, without limiting the generality of
the  foregoing,  all such costs and expenses in connection  with (1)  insurance,
(including without limitation rent insurance), license fees, janitorial service,
landscaping, and snow removal, (2) wages, salaries, management fees (which shall
be comparable to those fees for similar buildings),  employee benefits,  payroll
taxes,   on-site  office  expenses,   administrative   and  auditing   expenses,
professional  fees  (including,   without  limitation,   legal,  accounting  and
consulting  fees but excluding  legal fees relating to disputes with tenants and
excluding  consulting  fees  not  relating  to the  efficient  operation  of the
Building),  and  equipment  and materials  for the  operation,  management,  and
maintenance  of said Property,  (3) the  furnishing of heat,  air  conditioning,
utilities, and any other service to the extent to which Landlord is not entitled
to be  reimbursed  by  tenants,  (4)  water and sewer  rents,  and (5)  expenses
incurred in complying with all zoning and fire  regulations as they may apply to
the  Property  (except for  structural  changes and capital  expenditures)  (the
foregoing being hereinafter referred to as "operating expenses").  The following
shall be excluded from the definition of operating expenses:

(a) costs of special services rendered to
tenants for which a separate charge is made
or which is not an obligation of Landlord
under this Lease;

(b) costs incurred for the exclusive benefit of a specific tenant or
group of tenants or of a space occupied by Landlord;

(c) salaries of officers and executives of Landlord not connected with
the operation of the Property;

(d) any costs incurred by the negligent acts or omissions of Landlord,
its agents or employees;

(e) leasing fees or commissions and advertising costs;

(f) interest, mortgage charges, taxes,
depreciation, ground rent and capital
expenditures (including (as part of such
exclusion) amortization of the costs and the
cost of the financing thereof);

(g) costs of reconstruction or other work
incurred in connection with any fire or
other casualty insured or required to be
insured against hereunder;

(h) the cost of repair of damage caused by third
parties if reimbursement is received
therefor, Landlord agreeing to use
reasonable efforts to collect the same; if
such damage is caused by a tenant (other
than Tenant) which Landlord, acting
reasonably, has been able to identify, then
such cost shall not be included in this
subsection h, of this Lease;

(i)  expenses related to parking  operations  associated with the Building other
     than after hours security;

(j) the cost of installing, operating and
maintaining any specialty service, such as
an observatory, broadcasting facility,
luncheon club, retail store, sundry shop,
newsstand, concession, or athletic or
recreational club;

(k) the cost of correcting defects in base building construction (i.e. excluding
normal maintenance and repair expenses);

(1) insurance premiums to the extent any
tenant's particular use causes Landlord's
existing insurance premiums to increase or
require Landlord to purchase additional
insurance;

(m) any advertising or promotional expenses and objects of art;

(n) any costs representing an amount paid to an
entity related to Landlord which is in
excess of the amount which would have been
paid in the absence of such relationship;

(o) payments for rented equipment, the cost of
which equipment would constitute a capital
expenditure if the equipment were purchased;

(p) costs incurred due to violation by Landlord
or any tenant of the Building of any lease
or any laws, rules, regulations or
ordinances applicable to the Building;

(q) any expenditure which due to warranty, was
not made, or for which Landlord was
reimbursed, in the year establishing the
base amount of operating expenses; and

(r) Expenditures for capital items other than an
amount equal on a per annum basis to the
operating expenses that would have been
incurred for such period absent the
installation of any such capital item.

         Operating  expenses  shall  be  reduced  by  the  amount  of  insurance
proceeds,  reimbursements,  discounts  or  allowances  received  by  Landlord in
connection with such costs.

As soon as Tenant's  share of  operating  expenses  with respect to any calendar
year can be determined,  a statement of Tenant's share will be sent to Tenant at
which time said amount shall become payable to Landlord  within thirty (30) days
following the date of said  statement,  subject to proration with respect to any
portion  of a  calendar  year in which  the Term of this  Lease  begins or ends.
Landlord's  records of operating  expenses  with respect to each  calendar  year
shall be  available  for  inspection  by  Tenant  for six (6)  months  following
delivery by Landlord of its  statements  of  operating,  expenses for such year.
Tenant  may,  at  reasonable  time and after  notice to  Landlord,  inspect  all
invoices  and other  supporting  material  relevant to the  computation  of said
operating  expenses.  Tenant shall with each monthly installment of Annual Fixed
Rent,  make  operating  fund  payments to  Landlord.  The term  "operating  fund
payments" shall refer to such payments as Landlord shall reasonably determine to
be  sufficient  to provide in the  aggregate a fund  adequate to pay,  when they
become due and payable, all payments required from Tenant under this Section. In
calculating  operating  fund  payments,  Landlord  shall take into  account  the
operating  expenses  incurred  in the  previous  year.  In the  event  that  the
aggregate of said  operating fund payments is not adequate to pay Tenant's share
of  operating  expenses,  Tenant  shall pay to Landlord the amount by which such
aggregate  is less than the  amount of said  share,  such  payment to be due and
payable at the time set forth above.  Any surplus  operating fund payments shall
be accounted for to Tenant after such surplus has been determined,  and shall be
credited by Landlord  against future operating fund payments except that if such
surplus operating fund payment exceeds $1,500.00, it shall on Tenant's demand be
refunded to Tenant.  If such surplus fund payment exceeds the amount that should
have been paid by more than ten percent (10%),  Landlord shall pay to, or credit
Tenant (as the case may be) with  interest on such  surplus at an annual rate of
interest  equal to two percent  (2%)  greater  than the prime rate of  interest,
so-called,  of the  BankBoston,  N.A.,  in effect at the time. In the event of a
dispute between  Landlord and Tenant as to the propriety in the amount or nature
of any operating expense Landlord has requested Tenant to. pay, Tenant shall pay
the same at the time called for  hereunder as if the same were properly due, but
upon  notice  from  Tenant  to  Landlord,  the  matter  shall  be  submitted  to
arbitration in a manner reasonably  consistent with the provisions of Exhibit C,
hereto.

         4.2.4 Tenant's Proportionate Share.

         Tenant's proportionate share of taxes payable pursuant to Section 4.2.1
shall be the excess of real estate taxes allocable to the Premises over Tenant's
Included  Share of Real Estate Taxes,  where real estate taxes  allocable to the
Premises means the real estate taxes for the Property  multiplied by a fraction,
the  numerator  of  which is the  number  of  p.s.f.  of the  Premises,  and the
denominator of which is the number of p.s.f. in the Total Rentable Floor Area of
the  Building.  Tenant's  proportionate  share  of  operating  expenses  payable
pursuant to Section 4.2.3 shall be the excess of operating expenses allocable to
the Premises over Tenant's Included Share of Operating Expenses, where operating
expenses allocable to the Premises means the operating expenses for the Property
multiplied by a fraction,  the numerator of which is the number of p.s.f. of the
Premises  and the  denominator  of which is the  number of  p.s.f.  in the Total
Rentable Floor Area of the Building.

         Reference  is hereby  made to that  portion  of Article I of this Lease
which defines Tenant's Included Share of Real Estate Taxes and Tenant's Included
Share of Operating  Expenses for the purposes of the calculations  called for in
this Paragraph 4.2.4:

                                    (a) For the  period  commencing  January  1,
                  1998 and continuing  through  November 30, 1999, to the extent
                  that the operating  expenses  allocable to the Premises amount
                  to less than $4.50 per p.s.f.,  the amount of such  difference
                  shall be added to the $3.00  per  p.s.f.  figure  of  Tenant's
                  Included   Share  of  Real  Estate  Taxes.   Thus  by  way  of
                  hypothetical  example, if during any period within the Term of
                  this Lease the  operating  expenses  allocable to the Premises
                  are $4.15 per p.s.f., then during the period during which said
                  $4.15 per p.s.f. figure is applicable, Tenant's Included Share
                  of Real Estate  Taxes shall be treated as if it were $3.35 per
                  p.s.f.; and


                                    (b) For the period  commencing  December  1,
                  1999 and continuing  through  November 30, 2009, to the extent
                  that the operating  expenses  allocable to the Premises amount
                  to less than $5.60 per p.s.f.,  the amount of such  difference
                  shall be added to the $5.50  per  p.s.f.  figure  of  Tenant's
                  Included   Share  of  Real  Estate  Taxes.   Thus  by  way  of
                  hypothetical  example, if during any period within the Term of
                  this Lease the  operating  expenses  allocable to the Premises
                  are $5.00 per p.s.f., then during the period during which said
                  $5.00 per p.s.f. figure is applicable, Tenant's Included Share
                  of Real Estate  Taxes shall be treated as if it were $6.10 per
                  p.s.f.; and


                                    (c) For the  period  commencing  January  1,
                  1998 and continuing  through  November 30, 1999, to the extent
                  that the real estate taxes allocable to the Premises amount to
                  less than  $3.00 per  p.s.f.,  the  amount of such  difference
                  shall be added to the $4.50  per  p.s.f.  figure  of  Tenant's
                  Included  Share  of  Operating   Expenses.   Thus  by  way  of
                  hypothetical  example,  if the real estate taxes  allocable to
                  the  Premises  are $2.70 per  p.s.f.,  then  during the period
                  during  which  said  $2.70 per  p.s.f.  figure is  applicable,
                  Tenant's Included Share of Operating Expenses shall be treated
                  as if it were $4.80 per p.s.f., and


                                    (d) For the period  commencing  December  1,
                  1999 and continuing  through  November 30, 2009, to the extent
                  that the real estate taxes allocable to the Premises amount to
                  less than  $5.50 per  p.s.f.,  the  amount of such  difference
                  shall be added to the $5.60  per  p.s.f.  figure  of  Tenant's
                  Included  Share  of  Operating   Expenses.   Thus  by  way  of
                  hypothetical  example,  if the real estate taxes  allocable to
                  the  Premises  are $5.25 per  p.s.f.,  then  during the period
                  during  which  said  $5.25 per  p.s.f.  figure is  applicable,
                  Tenant's Included Share of Operating Expenses shall be treated
                  as if it were $5.85 per p.s.f.


         Notwithstanding the forgoing,  at no time during the term of this Lease
shall Tenant's  Included Share of Real Estate Taxes and Tenant's  Included Share
of Operating Expenses, taken together,  exceed the aggregate figure of $7.50 per
p.s.f. of the Premises for the period commencing  January 1, 1998 and continuing
through  November 30, 1999,  and $11. 10 for the period  commencing  December 1,
1999 and continuing through November 30, 2009.

         4.2.5 Tenant's Electricity Usage.

         Tenant  shall  utilize  metered  electricity  directly  from the public
utility  providing such to Tenant's Space ("Tenant's  Electricity") for Tenant's
use for all  purposes  for which  Tenant uses  electricity  including  lighting,
electrical  outlets  and  "HVAC",  so-called.  Landlord  shall allow its vaults,
wires,  risers and conduits to be used by Tenant,  acting  reasonably,  for such
purposes.  Such  facilities  shall be stubbed to a central  service area on each
floor. Tenant shall pay the cost of the same directly to such utility.  Landlord
shall furnish  electricity  for use in common areas,  Tenant's use of which,  if
consumed  during other than normal Building Hours (as defined in Exhibit G), and
to the extent of what  otherwise  would have been  supplied  (and then only upon
request  of Tenant may be  separately  charged  to  Tenant,  provided  that such
charges  shall be fairly  allocated  among all tenants  using such  electricity.
Tenant shall not,  without  Landlord's  prior consent in each instance,  connect
anything  to  the  Building's  electric  system  which  would  constitute  a use
inconsistent with the electrical system servicing the Premises.  Should Landlord
grant such consent,  all additional risers or other equipment  therefor shall be
provided by Landlord at the Tenant's  expense.  Landlord shall make arrangements
regarding  replacement of lighting tubes, lamps, bulbs and ballasts for Tenant's
Space at  Tenant's  expense,  -but to be billed to  Tenant at  Landlord's  cost,
reasonably calculated.





                                                     ARTICLE V

                                               LANDLORD'S COVENANTS

         5.1      Landlord's Covenants.

         Landlord covenants:

                                    5.  1.  1  to  furnish,  through  Landlord's
                  employees or independent  contractors,  the services listed in
                  Exhibit  G,  all  of  the  same  to  be  equivalent  to  those
                  customarily  supplied to first class  office  buildings in the
                  Boston and Cambridge areas.


                                    5.1.2  except  as  otherwise  provided  with
                  respect to Landlord's  Building  restoration  obligations  set
                  forth in  Article  VII,  to make  such  repairs  to the  roof,
                  structural elements,

foundation,  insulation, caulking, exterior walls and glass, floor slabs and all
parts  of  the  common  areas  and  facilities  of  the  Building,  Garage,  and
landscaping  as may be  necessary  to keep  them  in  condition  suitable  for a
first-class office building.

                  5.1.3 that  Landlord has the right to make this Lease and that
Tenant,  on paying the rent and performing its obligations in this Lease,  shall
peacefully  and quietly have,  hold and enjoy the Premises  throughout the Term,
subject to all terms and provisions hereof.

                  5.1.4  to keep the  Property  free of liens  for  unpaid  real
estate  taxes and to the extent  required by the terms of this Lease to maintain
insurance on the common areas.

         5.2      Interruptions.

         Landlord  shall  not be  liable  to  Tenant  for  any  compensation  or
reduction  of rent by  reason  of  inconvenience  or  annoyance  or for  loss of
business  arising  from  power and  other  utility  losses  and  shortages,  the
necessity  of  Landlord's  entering the Premises for any of the purposes in this
Lease  authorized,  or for repairing the Premises or any portion of the Property
however the necessity  may occur.  In case Landlord is prevented or delayed from
making any repairs,  alterations or improvements,  or furnishing any services or
performing  any other  covenant or duty to be performed on  Landlord's  part, by
reason of any cause reasonably beyond Landlord's control,  Landlord shall not be
liable to Tenant  therefor,  nor,  except as  expressly  otherwise  provided  in
Section 7. 1, shall Tenant be entitled to any  abatement or reduction of rent by
reason  thereof,  nor shall the same give rise to a claim in Tenant's favor that
such failure constitutes actual or constructive, total or partial, eviction from
the Premises.

         Upon  reasonable  prior  notice  (except  in  the  event  of  emergency
constituting an imminent threat to persons or property),  Landlord  reserves the
right to stop any  service  or  utility  system,  when  necessary  by  reason of
accident or emergency, or until necessary repairs have been completed, provided,
however,  that in each  instance  of stoppage or  interruption,  Landlord  shall
exercise reasonable diligence to minimize any inconvenience to Tenant.

         The foregoing provisions hereof to the contrary notwithstanding, in the
event any power or other utility  failure or service  failure (other than office
cleaning) which is an obligation of Landlord under this Lease (including failure
of elevator service and failure to repair any structural element of the Building
which Landlord is obligated to repair hereunder)  results in Tenant's  inability
to conduct its business on the  Premises  substantially  as permitted  hereunder
(herein,  a "Shutdown"),  and in the event such Shutdown continues for more than
fifteen business days or for more than five  consecutive  business days (in each
case) in any calendar year, then the Annual Fixed Rent hereunder shall be abated
for each  additional  business  day in such  calendar  year  during  which  such
Shutdown  continues.  Further,  if a Shutdown  continues for twelve  consecutive
months,  Tenant  shall have the right  thereafter,  by written  notice  given to
Landlord while such Shutdown continues, to terminate this Lease.

                                                    ARTICLE VI

                                                TENANT'S COVENANTS

         6.1      Tenant's Covenants.

         Tenant  covenants,  and with respect to the  provisions  of  Subsection
6.1.3,  below,  Landlord  covenants,  during the Term and such  further  time as
Tenant occupies any part of the Premises:

                                    6.1.1  to pay when  due all  fixed  rent and
                  additional  rent;  a late  charge of two  percent  (2%) on all
                  fixed and  additional  rent not paid within  three (3) days of
                  the date written  notice is given to Tenant that such rent has
                  not been paid,  which notice  shall not be given  earlier than
                  five (5) days after the day such rent is due;  all taxes which
                  may be imposed on Tenant's  personal  property on the Premises
                  (including   without   limitation,   Tenant's   fixtures   and
                  equipment) regardless to whomever assessed,  and to the extent
                  the nonpayment of the same would be a lien on any property, or
                  an  obligation  of the  Landlord,  all  charges by Landlord or
                  public utilities for electricity,  telephone, and gas services
                  and service  inspections  therefor,  and all charges by public
                  utilities for  installation of metering devices (which charges
                  shall be apportioned on a floor area basis for  multi-tenanted
                  floors).  Any  charge  by  Landlord  in  connection  with  the
                  provision of utilities or the  servicing  thereof  shall be at
                  the cost billed to Landlord for the same;


                                    6.1.2  except  as   otherwise   provided  in
                  Article  VII and  Sections  5.  1. 1 and  5.1.2,  to keep  the
                  Premises,  including  all  interior  glass,  clean and in good
                  order,  repair and  condition,  reasonable  wear and damage by
                  fire and casualty  only  excepted,  and at the  expiration  or
                  termination  of this Lease  peaceably to yield up the Premises
                  and all changes and  additions  therein in such order,  repair
                  and condition, first removing all goods, effects, and fixtures
                  of Tenant and any items the  removal of which is  required  by
                  any agreement given pursuant to Sections 3.1 or 3.2 hereof, or
                  specified therein to be removed at Tenant's election and which
                  Tenant  elects to remove,  and  repairing all damage caused by
                  such removal and restoring the Premises and leaving them clean
                  and neat;


                                    6.1.3 not to injure or deface the  Premises,
                  Building, Land, or Property, nor to permit in the Premises any
                  auction sale,  or nuisance,  or the emission from the Premises
                  of any  objectionable  noise or odor,  nor to commit or permit
                  any waste in or with  respect to the  Premises,  nor to use or
                  devote the Premises or any part thereof for any purpose  other
                  than  the  Permitted  Uses,  nor  any  use  thereof  which  is
                  improper,  offensive,  contrary to law or ordinance, or liable
                  to  invalidate,  or (unless Tenant pays the same, or if caused
                  by more than one party, its equitable share thereof)  increase
                  the  premiums  for,  any  insurance  on  the  Building  or the
                  Property  or its  contents or liable to render  necessary  any
                  alteration or addition to the Building or the Property;


                                    6.1.4  not to  obstruct  in any  manner  any
                  portion  of the  Building  not  hereby  leased or any  portion
                  thereof  or of the  Property  used by Tenant  in  common  with
                  others;  not without prior consent of Landlord  (which consent
                  shall not be  unreasonably  withheld or delayed) to permit the
                  painting  or  placing  of  any  signs  or the  placing  of any
                  curtains,  blinds, shades,  awnings,  aerials or flagpoles, or
                  the like,  visible  from outside the  Premises;  and to comply
                  with the Rules and  Regulations set forth in Exhibit H and all
                  other    reasonable   Rules   and   Regulations   of   general
                  applicability to all tenants in the Building hereafter made by
                  Landlord which Landlord shall use reasonable  efforts to apply
                  in a nondiscriminatory  manner, of which Tenant has been given
                  notice. Landlord shall not be liable to Tenant for the failure
                  of other  tenants of the Building to conform to such Rules and
                  Regulations.  In the event of any inconsistency between any of
                  said Rules and  Regulations  and the terms of this Lease,  the
                  terms of this Lease shall prevail;


         6.1.5 to keep the Premises equipped with all safety appliances required
by law or ordinance or any other regulation of any public  authority  because of
any use made by  Tenant  other  than the  Permitted  Uses,  and to  procure  all
licenses  and  permits so  required  because of such use and,  if  requested  by
Landlord,  to do any work so required  because of such use, it being  understood
that the  foregoing  provisions  shall not be  construed  to  broaden in any way
Tenant's Permitted Uses;

         6.1.6

                                    (a) That in the  event  Tenant  proposes  to
                  assign this Lease or sublet the Premises or any part  thereof,
                  Tenant shall give Landlord  written  notice thereof sixty (60)
                  days prior  thereto  which  notice  shall  specify the date on
                  which such  assignment  or subletting is to occur or commence.
                  Landlord  shall  then  have  a  period  of  thirty  (30)  days
                  following receipt of such notice within which to notify Tenant
                  in writing that Landlord elects (1) to terminate this Lease as
                  to the space so affected as of the date so specified by Tenant
                  but only for the term so  specified in which event Tenant will
                  be relieved of all further  obligations  hereunder  as to such
                  space on that date for the term so specified, or (2) to permit
                  Tenant  subject to all the remaining  terms and  provisions of
                  this  Lease  to  assign  this  Lease  or  sublet  such  space,
                  provided,  however, that in the case of such later election by
                  Landlord,  such  subletting or  assignment  shall be permitted
                  only to a party  with a  general  reputation  in the  business
                  community  comparable  to that  of  Tenant  and of  comparable
                  creditworthiness (but, with respect to any subletting,  taking
                  into account the amount of space sublet and the term thereof).
                  If  Landlord  shall  fail to notify  Tenant in writing of such
                  election within said thirty (30) day period, Landlord shall be
                  deemed to have elected option (2) above. If Landlord elects to
                  exercise  option  (2) above,  Tenant  agrees to provide at its
                  expense,  reasonable,  proper and legal direct access from the
                  assignment  or  subleased  space to a public  corridor  of the
                  Building.


                                    (b) If Landlord  consents to any  subletting
                  or  assignment  by  Tenant  as   hereinabove   provided,   and
                  subsequently  any  rents  received  by  Tenant  under any such
                  sublease  are in excess of the rent  payable  by Tenant  under
                  this lease, or any additional  consideration is paid to Tenant
                  by the assignee under any such assignment,  then fifty percent
                  (50%) of the  excess  rents  (after  deduction  for actual and
                  reasonable  "out of  pocket"  cash  expenses)  under  any such
                  sublease  or  the  additional   consideration   for  any  such
                  assignment  shall be due and  payable by Tenant to Landlord as
                  additional  rent  hereunder  when  received by Tenant,  Tenant
                  agreeing to use reasonable efforts to collect the same.


                                    (c) Notwithstanding anything to the contrary
                  contained  herein,  Tenant  shall have the  absolute  right to
                  assign  its  interest  in this  Lease or sublet  the  Premises
                  without  Landlord's  consent (and in such cases the  foregoing
                  subparagraphs  (a) and (b) shall not apply) in connection with
                  any assignment or sublease to any parent, subsidiary, or other
                  entity controlled by or under common control with Tenant;  any
                  assignment or sublease  occurring by operation of law; and any
                  assignment or sublease  occurring in connection with a sale of
                  all or  substantially  all of the  assets or capital or common
                  stock of Tenant or a consolidation or merger of Tenant.


                                    (d) No assignment  shall be deemed permitted
                  hereunder   unless   Tenant  shall   deliver  to  Landlord  an
                  instrument  in  recordable  form which  contains a covenant of
                  assumption by the assignee running to Landlord and all persons
                  claiming  by through  or under  Landlord,  but the  failure or
                  refusal  of  such  assignee  to  execute  such  instrument  of
                  assumption  shall not release or discharge  such assignee from
                  its liability hereunder nor shall execution of such instrument
                  of  assumption  affect the  continuing  primary  liability  of
                  Tenant.


                                    (e)  No  subletting  or  assignment  of  any
                  nature by Tenant shall relieve Tenant of any obligations under
                  this I-ease.


                                    (f)  Tenant  shall  have no right to  assign
                  this Lease or sublet all, or any portion of the Premises while
                  any  default  exists  hereunder  beyond any  applicable  grace
                  period.


                                    (g) No  assignment or sublease of any nature
                  may be made to any party who then is a tenant or  occupant  of
                  the Building unless Landlord, itself, is unable to satisfy the
                  need of such proposed assignee or sublessee.


         In the event of any  subletting  under this Lease pursuant to the terms
hereof,  upon the  request  of  Tenant,  Landlord  will  provide  the  subtenant
thereunder (the "Subtenant")  with an agreement binding upon Landlord  providing
that in the event of  termination  of the Lease by virtue of  Tenant's  default,
Landlord  will continue to recognize and accept the Subtenant as a tenant in the
sublet premises for the term of the Subtenant's  (sub) tenancy  provided (a) the
terms of such  subtenancy  are  identical to the  provisions of the Lease (or at
least no less favorable to Landlord)  other than (i) the rental,  tax escalation
and  operation  expense  payments  and the parking  space  allocation  under the
sublease may be reduced in proportion to the amount of floor space so subleased;
(H) the  Subtenant  shall have no rights to extend the term of the sublease past
the original term of the Lease or have any rights to expand its premises or take
advantage  of any  options  or  first  refusal  on  any  space  in the  Building
(including the space leased under the Lease but not demised under the sublease);
(iii) the term of such sublease shall not commence until after the  Commencement
date under the Lease  with the result  that  Tenant  shall have no  construction
obligations to the Subtenant under paragraph 3.1 of the lease; and (b) the floor
space covered by such  sublease  shall cover the entire amount (and no less than
the  entire  amount)  of one or more  "Sublease  Sections"  of the  Premises  as
referred to on Exhibit I hereto;

         6.1.7  To the  maximum  extent  this  agreement  may be made  effective
according,  damages,  losses, injuries or claims of whatever nature arising from
any act, omission or negligence of Tenant, or Tenant's  contractors,  licensees,
invitees, agents, servants or employees, or arising from any accident, injury or
damage  whatsoever  caused to any person or property,  occurring  after the date
that  possession of the Premises is first  delivered to Tenant and until the end
of the Term and  thereafter,  in or  about  the  Premises  or  arising  from any
accident,  injury or damage  occurring  outside  the  Premises  but  within  the
Building,  on the  Land or  with  respect  to the  parking  facilities  provided
pursuant to the Lease,  in each of the foregoing  instances where such accident,
injury  or  damage  results,  or is  claimed  to have  resulted,  from an act or
omission  on the part of Tenant or  Tenant's  agents  or  employees,  licensees,
invitees,  servants or contractors.  This indemnity and hold harmless  agreement
shall include indemnity against all costs,  expenses and liabilities incurred or
in connection with any such claim or proceeding brought thereon, and the defense
thereof.

         Tenant agrees to maintain in full force from the date upon which Tenant
first enters the Premises for any reason,  throughout the Term, and  thereafter,
so long as  Tenant  is in  occupancy  of any part of the  Premises,  a policy of
liability  insurance  more  particularly  described  below in this Section 6.1.7
under  which  Landlord  (and any ground  lessor and holder of a mortgage  on the
Property of whom Tenant has  knowledge)  and Tenant are named as  insureds,  and
under which the insurer provides a contractual  liability  endorsement  insuring
against all cost, expense and liability arising out of or based upon any and all
claims,  accidents,  injuries  and  damages  described  in  Section 7. 1, in the
broadest form of such coverage,  from time to time  available.  Each such policy
shall be  non-cancelable  and  non-amendable  (to the extent  that any  proposed
amendment  reduces  the limits or the scope of the  insurance  required  in this
Lease) with respect to Landlord and such ground lessors and  mortgagees  without
thirty (30) days' prior written  notice to Landlord and such ground  lessors and
mortgagees  and a duplicate  original  thereof  shall be  delivered to Landlord.
Without limitation of the foregoing,  the scope of such insurance shall include,
and the minimum  limits of liability of such  insurance  for each year shall be:
commercial general liability insurance, including broad form property damage and
contractual liability: general aggregate $2,000,000, each occurrence $1,000,000,
personal & advertising injury $1,000,000 and medical payments $5,000 per person;
employer's liability insurance covering bodily injury by disease with such limit
not less than  $1,000,000 for each person and a 1,000,000  policy limit;  bodily
injury  by  accident   with  limits  of  not  less  than   $1,000,000;   and  an
umbrella/excess  liability  policy  with  minimum  limits of  $5,000,000  in the
aggregate  and  $5,000,000  per  occurrence.  All  policies  shall be written by
companies rated not less than A - VIII by Best's Insurance Reports. Landlord may
from time to time during the Term hereof,  require higher limits, if such higher
limits are carried  customarily  in the  Boston-Cambridge  area with  respect to
similar  premises in similar  properties,  provided such  provision is uniformly
enforced within the Building;

                                    6.1.8 To keep all Tenant's employees working
                  in the Premises covered by workmen's compensation insurance in
                  statutory  amounts and to furnish  Landlord with  certificates
                  thereof;


                  6.1.9 Upon reasonable  prior notice other than in the event of
emergency  constituting  a threat to life or  property  to permit  Landlord  and
Landlord's  agents to examine the Premises and, if Landlord  shall so elect,  to
make  any  repairs  or  replacements  Landlord  may deem  necessary  to avert an
emergency,  to remove,  at Tenant's  expense,  any  changes,  additions,  signs,
curtains,  blinds,  shades,  awnings,  aerials,  flagpoles,  or  the  like,  not
consented to in writing (if such consent is required hereunder), and to show the
Premises to  prospective  tenants during the last twelve (12) months of the Term
or at any time after any notice of termination of this Lease, and to prospective
purchasers and prospective mortgagees at any time during the term of this Lease;


                  6.1.10  Not to place a load  upon the  Premises  exceeding  an
average rate of 50 pounds of live load per square foot of floor area; and not to
move any safe,  vault or other heavy  equipment in, about or out of the Premises
except in such  manner  and at such  times as  Landlord  shall in each  instance
authorize;  Tenant's  business  machines and  mechanical  equipment  which cause
vibration or noise that may be transmitted  to the Building  structure or to any
other leased space in the Building  shall be placed and  maintained by Tenant in
settings  of cork,  rubber,  spring,  or  other  type of  vibration  eliminators
sufficient to eliminate such vibration or noise;


                                    6.1.11   All  the   furnishings,   fixtures,
                  equipment,  effects and  property  of every  kind,  nature and
                  description of Tenant and of all persons  claiming by, through
                  or under Tenant which, during the continuance of this Lease or
                  any  occupancy  of the  Premises by Tenant or anyone  claiming
                  under  Tenant,  may be on the  Premises  or  elsewhere  in the
                  Building,  shall be at the sole risk and hazard of Tenant, and
                  if the whole or any part thereof shall be destroyed or damaged
                  by fire, water or otherwise,  or by the leakage or bursting of
                  water pipes, steam pipes, or other pipes, by theft or from any
                  other  cause,  no part of said loss or damage is to be charged
                  to or to be borne by Landlord  unless caused by the negligence
                  or willful misconduct of Landlord or its agents or employees;


                                    6.1.12  Not to suffer or permit any liens to
                  stand  against  the  Premises  by reason of work  done,  labor
                  services performed or materials provided for or at the request
                  of Tenant.  Tenant shall cause any such liens to be discharged
                  within  thirty (30) days after the date of notice to Tenant or
                  Tenant's  knowledge of the filing thereof,  but nothing herein
                  shall prevent Tenant from  contesting any such lien,  provided
                  that  Tenant  shall  first  provide  a  surety  bond or  other
                  security therefor satisfactory to Landlord;


                                    6.1.13 In case  Landlord  or  Tenant  shall,
                  without any fault on its part, be made party to any litigation
                  commenced by or against the other or by or against any parties
                  in possession  of the Premises or any party  thereof  claiming
                  under  the  other,  to  pay,  all  costs,   including  without
                  limitation,  reasonable  counsel  fees  incurred by or imposed
                  upon the other in connection with such litigation; and also to
                  pay  all  such  costs  and  fees  incurred  by  the  other  in
                  connection with the successful enforcement by the other of any
                  obligations  of the other under this Lease.  Any such payments
                  due from  Tenant  shall be deemed  Additional  Rent under this
                  Lease; and


                                    6.1.14 Upon the  expiration of this Lease or
                  should this Lease terminate for any cause,  and at the time of
                  such expiration or termination, the Tenant or Tenant's agents,
                  subtenants  or any other  person  should leave any property of
                  any kind or character on or in the premises,  the fact of such
                  leaving  of  property  on or in the Leased  Premises  shall be
                  conclusive  evidence of intent by the Tenant,  Tenant's agents
                  or subtenants, to abandon such property so left in or upon the
                  Premises, and such leaving shall constitute abandonment of the
                  property.


         Landlord,  its agents or attorneys,  shall have the right and authority
without  notice to Tenant,  Tenant's  agent or  subtenants,  or anyone else,  to
remove and destroy,  or to sell or authorize  disposal of such property,  or any
part  thereof,  without being in any way liable to the Tenant or any other party
therefore.  The  proceeds  received  therefor  shall  belong to the  Landlord as
compensation for the removal and disposition of said property.


         It is understood and agreed by and between the parties hereto that none
of Landlord's  servants,  agents or employees,  have or shall have the actual or
apparent authority to waive any portion of this paragraph,  and the Tenant shall
have no right to leave any such property  upon the Premises  without the written
consent of Landlord.


                                                    ARTICLE VII

                                                CASUALTY AND TAKING

         .7.1     Casualty and Taking.

                                    (a) If,  during the Term,  the  Building  or
                  Premises  shall be partially  damaged (as  distinguished  from
                  "substantially  damaged," as that term is hereinafter defined)
                  by  fire or  casualty,  Landlord  shall  proceed  promptly  to
                  restore the Building or Premises  (consistent,  however,  with
                  governmental   laws   and   codes   then  in   existence)   to
                  substantially  the  condition  thereof  at the  time  of  such
                  damage,  but Landlord  shall not be  responsible  for delay in
                  such  restoration  which may result from any cause  beyond the
                  reasonable control of Landlord.


                                    (b) If  during  the  Term  the  Building  or
                  Premises  shall be  substantially  damaged  (as  that  term is
                  hereinafter defined) by fire or casualty, the risk of which is
                  covered  by  Landlord's   insurance  and  the  holder  of  any
                  outstanding  mortgage  which  includes the Building as part of
                  the mortgaged  premises  (whose actions  shall,  to the extent
                  Landlord  acting  reasonably  can effect the same,  be in good
                  faith)  allows  the  insurance  proceeds  to be applied to the
                  restoration of the Building,  Landlord  shall,  promptly after
                  such  damage  and  the  determination  of the  net  amount  of
                  insurance  proceeds  available to Landlord,  expend so much as
                  may be  necessary  of such net amount to restore  (consistent,
                  however,  with  governmental laws and codes then in existence)
                  the  Building  and  Premises to  substantially  the  condition
                  thereof at the time of such damage,  but Landlord shall not be
                  responsible  for delay in such  restoration  which may  result
                  from any cause beyond the reasonable  control of Landlord.  If
                  the Building or the Premises shall be substantially damaged by
                  fire or  casualty  (a) as the result of a risk not  covered by
                  the forms of  casualty  insurance  at the time  maintained  by
                  Landlord, or (b) such holder of an outstanding mortgage (whose
                  actions shall, to the extent  Landlord  acting  reasonably can
                  effect  the  same,  be in  good  faith)  will  not  allow  the
                  insurance  proceeds  to be applied to the  restoration  of the
                  Building,   or  (e)  the  net  amount  of  insurance  proceeds
                  available  to Landlord are  insufficient  to cover the cost of
                  restoring the Building in the reasonable estimate of Landlord,
                  then  in any  such  case,  Landlord  may,  but  shall  have no
                  obligation to, restore (consistent, however, with governmental
                  laws  and  codes  then  in  existence)  the  Building  and the
                  Premises to substantially the condition thereof at the time of
                  such damage or  Landlord  may  terminate  this Lease by giving
                  notice  to  Tenant  within  forty-five  (45)  days  after  the
                  occurrence of such fire or casualty, which notice shall recite
                  the reason  among those set forth above for such  termination.
                  Landlord  shall  not  exercise  such  right  of   termination,
                  however,  unless, Landlord terminates all other leases then in
                  effect  in the  Building,  which  Landlord  has the  right  to
                  terminate by virtue of such casualty.

                                    (c) If  Landlord  shall  notify  Tenant that
                  Landlord  does not intend to restore the Building and Premises
                  by reason of the  unavailability or insufficiency of insurance
                  proceeds,  Tenant  shall  have  the  right  to  contribute  to
                  Landlord the amount of such insufficiency, and if Tenant shall
                  promptly notify Landlord of Tenant's desire to contribute such
                  insufficiency  and provide Landlord with security for Tenant's
                  undertaking in this respect satisfactory to Landlord, Landlord
                  shall promptly  commence and thereafter  diligently  pursue to
                  completion the restoration of the Building and Premises unless
                  otherwise excused by some other provision of this Article VII.


                                    (d) If Landlord  does not within  forty-five
                  (45) days after such fire or  casualty,  advise  Tenant of the
                  status   of   Landlord's    obligations    with   respect   to
                  reconstruction,  i.e.,  whether  the net  amount  of  proceeds
                  available to cover the cost of restoration  are sufficient for
                  restoration  which is expected to be completed  within six (6)
                  months; or that Landlord  reasonably expects to restore within
                  six (6) months  regardless of the  sufficiency or availability
                  of proceeds;  or that Landlord  intends to  terminate,  Tenant
                  itself  shall  have  the  right  until  Landlord   intends  to
                  terminate,  Tenant itself shall have the right until  Landlord
                  shall  have  notified  Tenant  of  Landlord's  intentions,  to
                  terminate  this Lease,  such  termination to take effect as of
                  the date of such Tenant's notice.


                                    (e) If the Premises  shall be  substantially
                  damaged  by fire or  casualty  within the last  eighteen  (18)
                  months of the Term (as the same may theretofore  have been, as
                  may  thereafter  be (by written  notice  given within ten (10)
                  days of any such  notice  by  Landlord)  extended  hereunder),
                  either  party  shall have the right,  by giving  notice to the
                  other not later than sixty  (60) days  after such  damage,  to
                  terminate this Lease,  whereupon this Lease shall terminate as
                  of the date of such notice.


                                    (f) The term "substantially  damaged as used
                  in this Article VII, shall refer to damage of such a character
                  that  the same  cannot,  in  ordinary  course,  reasonably  be
                  expected to be repaired  within ninety (90) days from the time
                  that repair work would commence.


                                    (g) Except as hereinafter  provided,  if the
                  Premises, or such portion thereof as to render the balance (if
                  reconstructed  to  the  maximum  extent   practicable  in  the
                  circumstances)  unsuitable  for  Tenant's  purposes,  shall be
                  taken by condemnation or right of eminent domain, Tenant shall
                  have the right to  terminate  this Lease by notice to Landlord
                  of its desire to do so, provided that such notice is given not
                  later than thirty (30) days after the  effective  date of such
                  taking.  If so much of the  Building  shall be so  taken  that
                  continued  operation  of the  Building  would  be  uneconomic,
                  Landlord  shall  have the  right to  terminate  this  Lease by
                  giving  notice  to Tenant  of  Landlord's  desire to do so not
                  later than thirty (30) days after the  effective  date of such
                  taking.


                                    (h)  Should any part of the  Premises  be so
                  taken or condemned during,  the Tenn, and should this Lease be
                  not  terminated in accordance  with the foregoing  provisions,
                  Landlord agrees to use due diligence to put what may remain of
                  the Premises (consistent,  however, with governmental laws and
                  codes  then in  existence)  and common  areas of the  Building
                  servicing  the  Premises  into  proper  condition  for use and
                  occupation as nearly like the condition of the Premises  prior
                  to such taking as shall be practicable.


                                    (i) If the Premises shall be damaged by fire
                  or other  casualty,  the Annual Fixed Rent and Additional Rent
                  shall be justly and equitably abated and reduced  according to
                  the nature and extent of the loss of use  thereof  suffered by
                  Tenant;   and  in  case  of  a  taking  which  temporarily  or
                  permanently   reduces  the  area  of  the  Premises,   a  just
                  proportion of the Annual Fixed Rent and Additional  Rent shall
                  be abated for the applicable portion or remainder, as the case
                  may be, of the Term.  In both cases,  above,  if any space not
                  damaged  or taken  nevertheless  becomes  unusable,  such fact
                  shall be taken into account when  calculating the rent for the
                  remaining space.


                                    (ii) In the event the  Premises  or Building
                  are damaged by fire or casualty and Landlord  either elects or
                  is  obligated  to  restore  the  same  pursuant  to any of the
                  foregoing  provisions of this Article VII, if Landlord has not
                  substantially  completed  (as that term is  defined in Section
                  3.1 hereof) such restoration  within six months of the date of
                  the  occurrence  of the fire or casualty  that has caused such
                  damage,  Tenant may terminate  this lease by written notice to
                  Landlord  given within ten business days after the end of such
                  six-month  period but in all events  prior to the time of such
                  substantial completion.


         7.2      Reservation of Award.

         Landlord  reserves to itself any and all rights to receive  awards made
for damages to the Premises and Building and Property and the  leasehold  hereby
created,  or any one or more of them,  accruing by reason of exercise of eminent
domain or by reason of anything  lawfully  done in  pursuance of public or other
authority. Tenant hereby releases and assigns to Landlord all Tenant's rights to
such awards,  and covenants to deliver such further  assignments  and assurances
thereof as Landlord may from time to time request.  It is agreed and understood,
however, that Landlord does not reserve to itself, and Tenant does not assign to
Landlord, any damages payable for (i) movable trade fixtures installed by Tenant
or  anybody  claiming  under  Tenant at its own  expense or  fixtures,  items or
leasehold  improvements,  whether  deemed realty or not, the removal of which is
required or permitted by any  agreement  given  pursuant to Sections 3.1 or 3.2,
and for which  Tenant  has paid the  entire  cost  thereof,  or (ii)  relocation
expenses recoverable by Tenant from such authority in a separate action.


                                                   ARTICLE VIII

                                                RIGHTS OF MORTGAGEE

         8.1      Superiority of Lease.

         Except as otherwise  provided in Section 8.6 below, this Lease shall be
superior to and shall not be  subordinated  to any  mortgage or other  voluntary
lien or other encumbrance arising after the date hereof on the Land or Building,
or both,  which are  separately  and together  hereinafter  in this Article VIII
referred to as "the mortgaged  premises."  The word  "mortgagee" as used in this
Lease  shall  include  the holder  for the time  being and any ground  lessor or
sublessor whenever the context permits.

         8.2      No Prepayment Payment.

         No fixed rent, additional rent, or any other charge shall be paid prior
to the due dates thereof and payments made in violation of this provision  shall
(except to the extent that such payments are actually received by a mortgagee in
possession  or in the process of  foreclosing  its  mortgage) be void as against
such  mortgagee  and Tenant  shall be liable for the amount of such  payments to
such mortgagee.

         8.3      No Release or Termination.

         No act or failure to act on the part of Landlord  which  would  entitle
Tenant  under the terms of this  Lease,  or by law,  to be  relieved of Tenant's
obligations  hereunder or to terminate this Lease,  shall result in a release or
termination of such obligations or a termination of this Lease unless (i) Tenant
shall have first given  written  notice of  Landlord's  act or failure to act to
Landlord's mortgagees of record, if any, specifying the act or failure to act on
the part of Landlord  which could or would give basis to  Tenant's  rights;  and
(ii) such  mortgagees,  after receipt of such notice,  have failed or refused to
correct or cure the condition complained of within a reasonable time thereafter;
but  nothing  contained  in this  Section  8.3 shall be  deemed  to  impose  any
obligation  on any  such  mortgagee  to  correct  or cure  any  such  condition.
Reasonable  times as used above means and includes a  reasonable  time to obtain
possession of the mortgaged  premises,  if the mortgagee  elects to do so, and a
reasonable  time,  not less  than  thirty  (30)  days,  to  correct  or cure the
condition if such condition is determined to exist.

         Notwithstanding  the  foregoing,   the  period  of  time  during  which
Landlord's  mortgagees shall have to cure the following  defaults or failures of
Landlord (should they occur):

(i) failure to provide power or other utility services or repairs required of
Landlord hereunder for a period in excess of twelve consecutive months as and to
the extent referred to in the last paragraph of subparagraph 5.2 above; and

          (ii) failure to substantially  complete restoration of the Building or
          Premises  after fire or casualty as and within the time  prescribed in
          subparagraph 7. 10) hereof;

          shall not be any longer  than the period of time  allotted to Landlord
          therefor under this Lease provided that (without  derogating  from any
          other  obligations or Tenant under this Lease) Tenant promptly deliver
          to each  such  mortgagee  of  record a copy of all  notices  and other
          communications  received  from and  which it  gives to  Landlord  with
          respect to any of the three foregoing enumerated matters.

         8.4      No Modification, etc.

         No  assignment  of this  Lease and no  agreement  to make or accept any
surrender,  termination or cancellation of this Lease and no agreement to modify
so as to reduce the rent,  change the Term, or otherwise  materially  change the
rights of Landlord under this Lease,  or to relieve Tenant of any obligations or
liability  under this Lease,  shall be valid  unless  consented to in writing by
Landlord's mortgagees of record, if any.


         8.5      Continuing Offer.

         The  covenants and  agreements  contained in this Lease with respect to
the rights, powers and benefits of a mortgagee (particularly, without limitation
thereby,  the covenants and agreement contained in this Article VIII) constitute
a  continuing  offer  to any  person,  corporation  or  other  entity,  which by
accepting or requiring an  assignment  of this Lease or by entry or  foreclosure
assumes the obligations  herein set forth with respect to such  mortgagee;  such
mortgagee is hereby constituted a party to this Lease as an obligee hereunder to
the same  extent  as  though  its name were  written  hereon  as such,  and such
mortgagee shall be entitled to enforce such provisions in its own name.

         8.6      Subordination.

         This Lease shall be subject and  subordinate  to any first  mortgage on
the  Building,  now or at any  time  hereafter  in  effect,  and to any  and all
advances  hereafter made thereunder,  and, in addition,  Landlord shall have the
option to  subordinate  this  Lease to any other  mortgage  which  includes  the
Premises  as part of the  mortgaged  premises,  provided  that the holder of any
mortgage of the nature  referred to in this Section 8.6 enters into an agreement
with  Tenant by the terms of which (a) in the event of  acquisition  of title by
such holder through foreclosure proceedings or otherwise, and provided Tenant is
not in default  hereunder to the extent that Landlord has the right to terminate
this Lease,  the holder will agree to recognize  the rights of Tenant under this
Lease  and to  accept  Tenant  as  tenant  of the  Premises  under the terms and
conditions of this Lease, subject to any rights of the Tenant regarding defaults
of the Landlord of which  Tenant has given  notice  pursuant to Section 8.3, and
(b) Tenant will agree to  recognize  the holder of such  mortgage as Landlord in
such event.  This  agreement  shall be made to  expressly  bind and inure to the
benefit  of the  successors  and  assigns  of Tenant  and of the holder and upon
anyone purchasing said Premises at any foreclosure sale.

         8.7      Implementation.

         Tenant  agrees on request  of  Landlord  to  execute,  acknowledge  and
deliver from time to time any agreement which may reasonably be deemed necessary
to effectuate the provisions of this Article VIII.

                                                    ARTICLE IX

                                                     DEFAULTS

9.1      Events of Default.

Each of the following shall be an Event of Default hereunder:

          (a)  If  Tenant  shall  default  in  the  performance  of  any  of its
          obligations  to pay  the  Annual  Fixed  Rent or any  Additional  Rent
          hereunder (a "monetary  default") and if such  monetary  default shall
          continue for ten (10) days after written  notice thereof (which notice
          for  the  purposes  of  this  paragraph  may  be  given  prior  to the
          expiration of the five (5) day period  referred to in Section 6. 1. 1,
          above);  (b) if within  thirty  (30) days after  written  notice  from
          Landlord to Tenant specifying any other default or defaults Tenant has
          not  commenced  diligently  to  correct  the  default or  defaults  so
          specified or has not thereafter  diligently pursued such correction to
          completion;  in the event (i) more than two written notices of default
          of the same type of obligation  are given in any calendar year or (ii)
          in the event more than five  written  notices of default of any nature
          are given in any  calendar  year,  then in either such  event,  Tenant
          shall pay to Landlord as rent and at the time the next rental  payment
          hereunder is due, the sum of One Thousand Dollars ($1,000.00) for each
          such notice in each such calendar year in excess of either two or five
          such notices as the case may be.

          (c) if any  assignment  shall be made by  tenant or any  guarantor  of
          Tenant for the benefit of creditors;

          (d) if Tenant's leasehold interest shall be taken on execution;

          (e) if a petition is filed by Tenant for  adjudication  as a bankrupt,
          or for  reorganization  or an  arrangement  under any provision of the
          Bankruptcy  Act as then in  force  and  effect,  or if an  involuntary
          petition under any of the  provisions of said  Bankruptcy Act is filed
          against Tenant and such  involuntary  petition is not dismissed within
          ninety (90) days thereafter.

                  Upon the  occurrence  of any Event of Default  then  remaining
uncured,  Landlord may  terminate  this Lease by notice to Tenant,  specifying a
date not less than ten (10) days after the  giving of such  notice on which this
Lease shall  terminate and this Lease shall come to an end on the date specified
therein as fully and completely as if such date were the date herein  originally
fixed for the  expiration of the Term of this Lease (Tenant  hereby  waiving any
rights of redemption  under MGLA c. 186,  ss.11),  and Tenant will then quit and
surrender  the  Premises  to  Landlord,   but  Tenant  shall  remain  liable  as
hereinafter provided.


         9.2      Remedies.

               (a) If this Lease shall have been  terminated as provided in this
               Article,  or if any  execution  or  attachment  shall  be  issued
               against Tenant or any of Tenant's property whereupon the Premises
               shall be taken or occupied  by someone  other than  Tenant,  then
               Landlord may,  without notice,  re-enter the Premises,  either by
               force,  summary proceedings,  ejectment or otherwise,  and remove
               and  dispossess  Tenant  and all  other  persons  and any and all
               property from the same,  as if this Lease had not been made,  and
               Tenant  hereby  waives the  service of notice by  Landlord of its
               intention to re-enter or to institute  legal  proceedings to that
               end.

               (b) In the event of any termination,  Tenant shall pay the Annual
               Fixed Rent,  Additional Rent and all other sums payable hereunder
               up to the time of such termination,  and thereafter Tenant, until
               the end of what  would  have  been the Term of this  Lease in the
               absence of such  termination,  and  whether  or not the  Premises
               shall have been relet, shall be liable to Landlord for, and shall
               pay to Landlord,  as liquidated current damages, the Annual Fixed
               Rent,  Additional  Rent and other  sums  which  would be  payable
               hereunder  if such  termination  had not  occurred,  less the net
               proceeds,  if  any,  of  any  reletting  of the  Premises,  after
               deducting  all  reasonable   expenses  in  connection  with  such
               reletting,   including,   without   limitation,   all  reasonable
               repossession  costs,  brokerage   commissions,   legal  expenses,
               attorneys, fees, advertising,  expenses of employees,  alteration
               costs and  expenses of  preparation  for such  reletting.  Tenant
               shall pay such  current  damages to Landlord  monthly on the days
               which the Annual Fixed Rent, Additional Rent and other sums would
               have  been   payable   hereunder  if  this  Lease  had  not  been
               terminated.

                    (c) At any  time  after  such  termination,  whether  or not
                    Landlord shall have collected any such current  damages,  as
                    liquidated  final  damages  and in lieu of all such  current
                    damages  beyond the date of such demand,  at the election of
                    Landlord  exercisable  at  any  time,  Tenant  shall  pay to
                    Landlord  an  amount  equal to the  excess,  if any,  of the
                    Annual Rent,. Additional Rent and other sums as hereinbefore
                    provided  which would be payable  hereunder from the date of
                    such  demand  (assuming  that,  for  the  purposes  of  this
                    paragraph,  annual  payments  by Tenant on  account  of Real
                    Estate Taxes and operating Expenses would be the same as the
                    payments required for the immediately preceding Operating or
                    Tax Year) for the  remainder  of the Term of this  Lease had
                    the same  remained in effect,  over the then fair net rental
                    value of the Premises for the same period.

                    (d) In case of any Default by Tenant,  re-entry,  expiration
                    and  dispossession  by  summary  proceedings  or  otherwise,
                    Landlord  may (i) acting,  reasonably  relet the Premises or
                    any part or parts thereof,  notwithstanding  that this Lease
                    may not have been terminated,  for a term or terms which may
                    at Landlord's  option be equal to or less than or exceed the
                    period which would otherwise have constituted the balance of
                    the Term of this  Lease  and may grant  concessions  or free
                    rent to the extent that  Landlord  considers  advisable  and
                    necessary   to  relet  the  same  and  (ii)  may  make  such
                    reasonable  alterations,  repairs  and  decorations  in  the
                    Premises  as  Landlord  in  its  sole   judgment   considers
                    advisable  and  necessary  for, the purpose of reletting the
                    Premises;  and the making of such  alterations,  repairs and
                    decorations  shall not  operate or be  construed  to release
                    Tenant from liability hereunder as aforesaid. Landlord shall
                    in no event be liable in any way  whatsoever  for failure to
                    relet the  Premises,  or, in the event that the Premises are
                    relet, for failure to collect the rent under such reletting.
                    Tenant  hereby  expressly  waives  any  and  all  rights  of
                    redemption granted by or under any present or future laws in
                    the event of Tenant being evicted or dispossessed, or in the
                    event of Landlord obtaining  possession of the Premises,  by
                    reason of the  violation  by Tenant of any of the  covenants
                    and conditions of this Lease.

                    (e) Landlord may invoke any remedy  (including the remedy of
                    specific  performance)  allowed  at law or in  equity  as if
                    specific remedies were not herein provided for.

                    (f) Upon the  occurrence  of an Event of Default  which is a
                    monetary  default (as defined in Paragraph 9. 1 (a),  above)
                    and notwithstanding that any other Event of Default which is
                    not a  monetary  default  shall  have  occurred  and  remain
                    uncured at the time; or upon the  termination  of this Lease
                    for  the  occurrence  of an  Event  of  Default  which  is a
                    monetary default,  notwithstanding that such termination may
                    also have  been  effected  because  of the  occurrence  of a
                    default  other than a monetary  default,  then and in either
                    such event,  in  addition to having the rights and  remedies
                    set forth in Paragraph  9.1 hereof and 9.2 hereof,  Landlord
                    may invoke any other  remedy and seek any other  damages not
                    specifically provided for in said Paragraphs 9.1 and 9.2.

                    Upon the  occurrence of one or more Events of Default,  none
                    of which is a monetary default (as defined in Paragraph 9. 1
                    (a) above);  or upon the  termination  of this Lease for the
                    occurrence  of one or more Events of Default,  none of which
                    is a  monetary  default,  then  and in  either  such  event,
                    Landlord's  rights,  remedies and damages on account of such
                    Event of  Default or  termination  shall be limited to those
                    set forth in Paragraph 9.1 and in Subparagraphs 9.2(a), (b),
                    (c), (d) and, to the extent of injunctive relief, (e) above.











                                                     ARTICLE X

                                                   MISCELLANEOUS

         10.1 Intentionally Deleted.

         10.2 Titles.

         The titles of the Articles are for  convenience  only and are not to be
considered in construing this Lease.

         10.3 Notice of Lease.

         Landlord and Tenant  agree that neither  party shall record this Lease.
Upon request of either party, both parties shall execute and deliver a notice of
this Lease in form appropriate for recording or registration,  and if this Lease
is  terminated  before  the  Lease  Term  expires,  an  instrument  in such form
acknowledging the date of termination.

         10.4 Holding Over.

         Any holding  over of the  Premises by Tenant  after the  expiration  or
earlier  termination  of the Term or any  extension  or renewal  thereof  shall,
subject to the  application  of the  provisions  of  Paragraph  10.  16,  below,
constitute  Tenant a trespasser of the Premises  unless prior to such expiration
or termination  Landlord has executed a written  instrument with Tenant in which
Landlord  agrees to an extension of the term of this I-ease.  If Tenant so holds
over,  Landlord by a written notice to Tenant may declare the Tenant a tenant at
will and the  tenancy so  created  may be  terminated  by not less than ten (10)
days,  written notice by either party to the other.  In the event Landlord makes
such  declaration,  the  tenancy  shall  be  subject  to all of  the  terms  and
provisions of this Lease except that it shall be  terminable  as above  provided
and the rent  during such  tenancy  shall be 150% of the total  average  monthly
rental payable by Tenant to Landlord for the  immediately  preceding  lease year
including but not limited to Annual Fixed Rent, and Additional  Rent as provided
in this Lease.

         10.5 Notice.

         Whenever any notice, approval, consent, request or election is given or
made pursuant to this Lease it shall be in writing, notwithstanding that certain
references in this Lease to requirements for notice may not call for the same to
be in writing.  Communications and payments shall be addressed if to Landlord at
Landlord's  Original Address or at such other address as may have been specified
by prior notice to Tenant,  and if to Tenant, at Tenant's Original Address prior
to the commencement date and thereafter at the Premises or at such other address
as may have been  specified by prior notice to Landlord  with a copy sent in the
case of notices to Tenant in the same manner and to the same  address  addressed
to "Corporate Counsel". Any communication or notice so addressed shall be deemed
duly served  when  delivered  in hand or upon  delivery  or  attempted  delivery
following deposit in the U.S. mail, registered mail, return receipt requested.

         10.6 Bind and Inure.

         The  obligations  of this Lease shall run with the land, and this Lease
shall be binding  upon and inure to the benefit of the parties  hereto and their
respective successors and assigns,  except that only the original Landlord named
herein  shall be liable for  obligations  accruing  before the  beginning of the
Term,  and thereafter  the original  Landlord  named herein and each  successive
owner of the Premises shall be liable only for the  obligations  accruing during
the period of its  ownership.  Whenever  the  Premises are owned by a trustee or
trustees,  the  obligations of Landlord shall be binding upon  Landlord's  trust
estate, but not upon any trustee or beneficiary of the trust individually.

         10.7 No Surrender.

         The delivery of keys to any employee of Landlord or to Landlord's agent
or any employee  thereof shall not operate as a  termination  of this Lease or a
surrender of the Premises.

         10.8 No Waiver, Etc.

         The failure of Landlord or of Tenant to seek redress for  violation of,
or to insist upon the strict  performance  of, any covenant or condition of this
Lease or any of the Rules and Regulations referred to in Section 6.1.4 shall not
be deemed a waiver of such  violation nor prevent a subsequent  act, which would
have originally constituted a violation, from having all the force and effect of
an original violation.  The failure of Landlord to enforce any of said Rules and
Regulations  against any tenant in the Building  shall not be deemed a waiver of
any such rules or  regulations,  but  Landlord  shall not enforce such Rules and
Regulations  inconsistently  or adopt  any new  rules or  regulations  which are
unreasonable.  The  receipt by Landlord  of fixed rent or  additional  rent with
knowledge  of the breach of any covenant of this Lease shall not be deemed to be
a waiver of such breach by Landlord,  unless such waiver be in writing signed by
Landlord. No consent or waiver,  express or implied, by Landlord or Tenant to or
of any breach of any agreement or duty shall be construed as a waiver or consent
to or of any other breach of the same or any other agreement or duty.

         10.9 No Accord and Satisfaction.

         No  acceptance  by  Landlord  of a lesser  sum than the fixed  rent and
additional  rent then due shall be deemed  to be other  than on  account  of the
earliest installment of such rent due, nor shall any endorsement or statement on
any check or any letter  accompanying  any check or payment as rent be deemed an
accord and  satisfaction,  and Landlord may accept such check or payment without
prejudice  to  Landlord's  right to recover the balance of such  installment  or
pursue any other remedy provided in this Lease.  Notwithstanding anything to the
contrary herein, in the event of a dispute,  Tenant may make any payment of rent
when due under protest but nothing shall relieve  Tenant of its  obligations  to
punctually and duly perform its obligations hereunder.

         10.10 Cumulative Remedies.

The specific  remedies to which  either  Landlord or Tenant may resort under the
terms of this Lease are  cumulative  and are not intended to be exclusive of any
other remedies or means of redress to which it may be lawfully  entitled in case
of any breach or threatened  breach by the other party of any provisions of this
Lease.  In addition to the other remedies  provided in this Lease,  Landlord and
Tenant shall be entitled to the  restraint  by  injunction  of the  violation or
attempted  or  threatened  violation  of  any of the  covenants,  conditions  or
provisions of this Lease or to a decree compelling  specific  performance of any
such covenants, conditions or provisions.

         10.11 Partial Invalidity and Applicable Law.

         This Lease shall be governed by and  construed in  accordance  with the
laws of The Commonwealth of  Massachusetts  and, if any provisions of this Lease
shall to any  extent  be  invalid,  the  remainder  of this  Lease  shall not be
affected thereby.  There are no oral or written  agreements between Landlord and
Tenant  affecting  this  Lease.  This Lease may be amended,  and the  provisions
hereof nay be waived or modified,  only by instruments  in writing.  executed by
Landlord and Tenant.

         10.12 Landlord's Right to Cure Tenant's Default.

         If  Tenant  shall  at  any  time  default  in  the  performance  of any
obligation  under this Lease,  Landlord  shall have the right,  but shall not be
obligated,   to  enter  upon  the  Premises  and  to  perform  such   obligation
notwithstanding  the fact  that no  specific  provisions  for  such  substituted
performance  by Landlord  are made in this Lease with  respect to such  default.
Except in case of emergency, these rights shall be exercised only after ten (10)
days prior written notice from Landlord to Tenant of Landlord's  intention to do
so. In  performing  such  obligation,  Landlord may make any payment of money or
perform any other act. All sums so paid by Landlord  (together  with interest at
an annual rate equal to the prime rate of interest  announced  from time to time
by  BankBoston,  N.A.,  plus  two  percentage  points  (2%)  and  all  necessary
incidental costs and expenses in connection with the performance of any such act
by Landlord shall be deemed to be additional  rent under this Lease and shall be
payable to Landlord  immediately on demand.  Landlord may exercise the foregoing
rights without  waiving any other of its rights or releasing  Tenant from any of
its obligations under this Lease.

         10.13 Estoppel Certificates.

Tenant shall from time to time, upon request by Landlord,  execute,  acknowledge
and deliver to Landlord or Landlord's designee a statement in writing certifying
that this Lease is  unmodified  and in full force and effect and that Tenant has
no defenses,  offsets or counterclaims  against its obligations to pay the fixed
rent and additional rent and to perform its other covenants under this Lease and
that there are no uncured  defaults of Landlord or Tenant  under this Lease (or,
if there have been any modifications,  that the same is in full force and effect
as  modified  and  stating the  modifications  and,  if there are any  defenses,
offsets,  counterclaims or defaults,  setting them forth in reasonable  detail),
and the dates to which the fixed rent,  additional  rent and other  charges have
been paid. Any such statement  delivered  pursuant to this Section 10. 13 may be
relied  upon by any  prospective  purchaser  or  mortgagee  of the  Building  or
Property.

         Landlord  shall  from time to time upon  request  of  Tenant,  execute,
acknowledge and deliver to Tenant, or Tenant's designee,  a statement in writing
reciting (to the extent  Landlord  acting  reasonably  considers  the same to be
accurate)  that this Lease is unmodified  and in full force and effect;  that no
moneys are due from Tenant to Landlord  hereunder;  that Tenant has not asserted
in writing any offsets  against payment of the rent or other sums due hereunder,
and that no notice of default given by Landlord to Tenant remain outstanding.

         10.14 Waiver of Subrogation.

         Any insurance  carried by either party with respect to the Premises and
property  therein or occurrences  thereon shall,  if the other party so requests
and if it can be so written without  additional  premium,  or with an additional
premium  which the other party  agrees to pay,  include a clause or  endorsement
denying to the  insurer  rights of  subrogation  against  the other party to the
extent  rights have been waived by the insured  prior to occurrence of injury or
loss. Each party,  notwithstanding any provisions of this Lease to the contrary,
hereby waives any rights of recovery against the other for injury or loss due to
hazards covered by insurance containing such clause or endorsement to the extent
of the greater of  indemnification  received  thereunder  or the full  insurable
value of the portion of the Premises so damaged.

         10. 15 Brokerage.

         Tenant warrants and represents  that,  except as hereinafter set forth,
it has not dealt with any real estate  broker or agent in  connection  with this
Lease or its  negotiation.  Tenant  represents that it has employed  Spaulding &
Slye as its broker at its own expense.  Tenant shall indemnify Landlord and hold
Landlord harmless from any cost,  expense or liability  (including costs of suit
and reasonable attorney's fees) for any compensation, commission or fees claimed
by Spaulding & Slye or any other real estate broker or agent in connection  with
this Lease or its negotiation by reason of any act of Tenant.  Landlord warrants
and  represents  that it has not dealt with any real  estate  broker or agent in
connection with this Lease or its  negotiation,  and shall indemnify  Tenant and
hold Tenant harmless from any costs,  expense or liability  (including  costs of
suit and reasonable  attorney's fees) for any  compensation,  commission or fees
claimed  by any real  estate  broker or agent  other  than  Spaulding  & Slye in
connection with this Lease or its negotiation by reason of any act of Landlord.

         10.16 Force Majeure.

         Except  to the  extent,  if any,  otherwise  specifically  provided  in
Articles  III,  V and VII,  above,  in any case  where  either  party  hereto is
required to do any act, and is prevented or delayed in its  performance  thereof
by or  resulting,  from an act of  God,  war,  civil  commotion,  fire or  other
casualty,  labor  difficulties,  shortages  of labor,  materials  or  equipment,
governmental  regulations,  act of the other party,  or other causes beyond such
party's reasonable control (other than financial inability),  the period of time
during,  which it is so prevented or delayed shall not be counted in determining
the  time  during  which  such  act is to be  performed,  whether  such  time be
designated by a fixed date, a fixed time or a  "reasonable  time" and such party
shall have no liability by reason thereof.




         10.17 Authority.

         If Tenant is a corporation, Tenant warrants that it has legal authority
to  operate  and  is   authorized  to  do  business  in  The   Commonwealth   of
Massachusetts.  Tenant also warrants that the person or persons  executing  this
Lease on behalf of Tenant has or have  authority  to do so and fully to obligate
Tenant to all terms and  provisions of this Lease.  Tenant  shall,  upon request
from Landlord, furnish Landlord with a clerk's certificate of votes of its Board
of Directors  authorizing this Lease and granting authority to execute it to the
person or persons who have executed it on Tenant's behalf.

         Landlord  warrants  that  it has  legal  authority  to  operate  and is
authorized to do business in The  Commonwealth of  Massachusetts.  Landlord also
warrants that the person or persons  executing  this Lease on behalf of Landlord
has or have  authority to do so and fully to obligate  Landlord to all terms and
provisions of this Lease.

         10. 18 Parking.

         Landlord shall provide Tenant with parking,  as hereinafter  set forth,
upon payment of the then  monthly rate for parking  spaces in the area(s) on the
property  designated  by the  Landlord  for  parking.  The monthly rate for each
parking  space shall be $190.00 per month for the one year period  beginning  on
the Term  Commencement  Date and shall thereafter be the prevailing  market rate
for parking  spaces in garages in  comparable  buildings  located in the area of
Cambridge,  Massachusetts  where the Building is located.  Tenant shall abide by
any and all reasonable parking  regulations and rules established by Landlord or
Landlord's parking operator. Tenant shall be provided with one (1) parking space
for every 1,000  p.s.f.  of the  Premises.  A fraction  of 1/2 or greater  shall
entitle  Tenant to a full  parking  space.  Tenant  shall  specify the number of
spaces  required from time to time, up to its permissible  maximum,  upon thirty
(30) days' advance  written notice to Landlord and shall pay the charge therefor
from and after the date of delivery of such space.  In the event Tenant does not
require the use of all of its  permissible  maximum  number of parking,  spaces,
Landlord may  allocate  unused  parking  spaces to other  users,  provided  such
parking  spaces  shall be made  available to Tenant  within  thirty (30) days of
Tenant's notice that such parking spaces are required.

         10.19 Building Directory.  Tenant shall have the right to not more than
Tenant's then percentage of the rentable area of the Building,  calculated as in
Section 4.2.4,  above,  of the listings on the lobby  directory of the Building.
The  listing  of one or more names of  persons  other than  Tenant on such lobby
directory  shall not be construed as a consent by Landlord to an assignment or a
subletting by Tenant to such person or persons. Landlord agrees while this Lease
is in effect (i) not (of its own  initiative)  to change the present  address of
the Building,  and (ii) not to name the Building after a business  competitor of
Tenant.

         10.20 Tenant's Right to Cure.

         If Landlord  defaults in the  performance  or  observance of any of its
covenants or  obligations  set forth in this Lease,  Tenant shall give  Landlord
notice  specifying in what manner  Landlord has defaulted and if Landlord  shall
not within twenty (20) days of such notice  commence and  thereafter  diligently
pursue to completion the cure of such default (except that if such default shall
render the Premises or any part thereof  exceeding  twenty percent (20%) thereof
unusable for the Permitted Uses or shall  constitute an immediate danger to life
or  property  the initial  twenty (20) day period  described  above  shall,  for
purposes  of this  paragraph,  be  deemed  to be three  (3)  days),  Tenant  may
forthwith cure the same and invoice  Landlord for costs and expenses  (including
reasonable  attorneys'  fees and court  costs)  incurred by Tenant in curing the
same,  together with interest from the date Landlord  receives Tenant's invoice,
at a rate equal to the lesser of two  percent (2 %) over the base rate in effect
from time to time at BankBoston,  N.A. or the maximum rate allowed by law. In no
event,  however,  shall  such right to  reimbursement  give rise to any right of
setoff  or other  reduction  of the rent or any  other  sum due from  Tenant  to
Landlord  hereunder,  Tenant's  sole remedy being the right to bring a separate,
independent suit against Landlord for such reimbursement.

         10.21 Certain Other Matters.

                    (a)  Insofar  as the  same  relate  to the  Premises  or the
                    Building,  Tenant  agrees  to comply at all times at its own
                    expense  with all  Federal,  State and  local  environmental
                    protection laws, so-called,  and all rules,  regulations and
                    ordinances  relating thereto,  including without limitation,
                    Massachusetts General Laws c. 21E, the Federal Comprehensive
                    Environmental  Response  Compensation and Liability Act, the
                    Federal  Resource  Conservation  and  Recovery  Act  and all
                    amendments thereto.

                    (b) Tenant will  neither  permit nor suffer the  presence of
                    any  hazardous  materials (as that term is defined in any of
                    the  foregoing  statutes) on the premises at any time except
                    only for  reasonable  amounts  of  customarily  used  office
                    supplies  and  cleaning   materials  and,  upon  request  of
                    Landlord,  will  deliver  to  Landlord a list  reciting  the
                    identity and quantity of all such hazardous materials on the
                    premises.  Tenant will make no unlawful use of any hazardous
                    materials  and will neither  suffer nor permit any threat of
                    release, release or any other improper discharge thereof. If
                    any  threat  of  release  or  release  occurs,  Tenant  will
                    promptly  remediate  the  same  at its  own  expense  and in
                    accordance  with all  applicable  law.  In the event  Tenant
                    receives any notice from any regulatory agency or other such
                    party  requiring any action with respect to the  remediation
                    of any  threat  of  release  or  release  of  any  hazardous
                    materials,   Tenant  will  promptly  fully  notify  Landlord
                    thereof.  Tenant will  indemnify and save Landlord  harmless
                    from all loss, cost and expense Landlord may suffer or incur
                    in  connection  with the failure of Tenant to perform any of
                    its obligations hereunder,  the provisions of this paragraph
                    to survive and remain  operative  after  termination of this
                    Lease for any reason.

                    (c) Landlord  agrees to indemnify  and save Tenant  harmless
                    from all loss,  cost and expense  Tenant may suffer or incur
                    by virtue of any  violation  by Landlord  of any law,  rule,
                    regulations  or  ordinance  referred  to in (a) above to the
                    extent of any personal  injury or property damage or cost to
                    Tenant of any remediation activity Tenant by law is required
                    to  perform.  In the event  Tenant  suffers any such loss by
                    virtue of the activity of any other tenant in the  Building,
                    Landlord at Tenant  expense  will  enforce such rights as it
                    has  against  such  Tenant,  the  result of which will be to
                    indemnify  Tenant from and  against all such loss.  Landlord
                    further  agrees to indemnify  and save Tenant  harmless from
                    all loss,  cost and  expense  Tenant  may suffer or incur in
                    connection  with the Premises by reason of the  violation by
                    Landlord of any other law, ordinance or regulation  relating
                    to the Building or the Premises.

                                    (d)  This  Lease  may  be  executed  by  the
                  parties hereto by means of multiple  counterparts  which, when
                  taken together, shall constitute one document.


         10.22 Prior Lease.  Reference is made to the lease dated as of June 15,
1989,  as amended by that  certain  Amendment to Lease dated as of May 31, 1990,
that  certain  Second  Amendment to Lease dated as of December 31, 1992 and that
certain  Settlement  Agreement dated as of June 23, 1992,  between  Landlord and
Tenant  (collectively,  the "Prior  Lease"),  pursuant to which the Premises are
currently  demised  by  Landlord  to  Tenant.  This Lease  shall  constitute  an
amendment  and  restatement  in whole of the  Prior  Lease,  provided  that such
amendment and restatement  shall not be construed as relieving either party from
any undischarged obligations arising under the Prior Lease.

EXECUTED as a sealed instrument as of the day and year first above written.


Landlord:

ONE MEMORIAL DRIVE LIMITED
PARTNERSHIP

By: One Memorial Drive Property
Management, Inc., its agent


By:_____________________________
Dean F. Stratouly,
President

Tenant:

PUTNAM, HAYES & BARTLETT,
INCORPORATED

By:/s/ Barbara J. Levine____________
Name: Barbara J. Levine
Title: Corporate Counsel
hereunto duly authorized

<PAGE>


                                                CERTIFICATE OF VOTE
                                                        OF
                                      PUTNAM, HAYES & BARTLETT, INCORPORATED

         I, the undersigned, hereby certify that I am the Clerk of Putnam, Hayes
& Bartlett,  Incorporated, a Massachusetts corporation,  duly elected, qualified
and  acting as such;  that as such Clerk I have  custody  of the  minutes of the
meetings of the Board of  Directors  of said  corporation;  that at a meeting of
said Board of  Directors  duly  called and held  on_________,  199_,  at which a
quorum of the Directors was present and voted throughout, it was unanimously

         VOTED:            That this  corporation  lease from One Memorial Drive
                           Limited  Partnership an area of approximately  55,763
                           square feet of floor space in the building located at
                           One Memorial Drive, Cambridge, Massachusetts, at such
                           rental,  for such period of time, and upon such other
                           terms and conditions as_________________,
                                    of  this   corporation   may  in  his   sole
                           discretion deem advisable;  that the said , be and he
                           hereby is  authorized  and  directed  to execute  and
                           deliver  on  behalf  of  this  corporation  a form of
                           lease,     Notice    of     Lease,     Subordination,
                           Non-Disturbance  and  Attornment  Agreement  and such
                           other documents, all in such form and upon such terms
                           and  conditions  as the said in his  sole  discretion
                           shall deem appropriate in the circumstances; and that
                           the  execution  and  delivery of each  thereof by the
                           said shall be  conclusive  evidence  that each of the
                           sane shall have been authorized hereby.

         I further certify that  ___________________  presently is Clerk of said
corporation,  that the foregoing  vote presently is in full force and effect and
has not  been  modified  or  amended,  and  that  the  passage  of the  same was
consistent with and not in violation of the bylaws,  charter and other governing
documents of said corporation.

Dated: January, _ 1998                      __________________________________
Clerk, Putnam, Hayes & Bartlett, Incorporated



<PAGE>


                                                     EXHIBIT A
                                           LEGAL DESCRIPTION OF THE LAND

         A parcel of land,  partly registered and partly  unregistered  shown as
containing  74,283 + square feet  according to a plan  entitled  "Plan of and in
Cambridge,  Mass", dated April 8, 1974 by William S. Crocker,  Inc. and recorded
with the Middlesex  South Registry of Deeds in Book 12634,  Page 63, and bounded
and described according to that plan as follows:

NORTHERLY by Main Street, five hundred forty-one and 35/100 feet;
SOUTHEASTERLY by the Esplanade, so called, four hundred seventy-six and
11/100 feet;
SOUTHWESTERLY one hundred twenty-feet;
NORTHWESTERLY nineteen and 85/100;
SOUTHERLY seventy-six and 34/100 feet; and
NORTHWESTERLY one hundred twenty-five and 118/1000 feet, this and said
last three courses being by land now or formerly of
Arthur D. Little, Inc. (although not so marked on said
plan).

Together with the buildings, improvements, and fixtures located thereon.

         There are  included  in the land  conveyed  hereby  the  following  two
parcels of registered land:

         The first registered parcel is shown as Lot F on Land Court Plan 2090C,
filed with Certificate 8538 in Registration  Book 58, Page 309, in the Middlesex
South Registry District of the Land Court, bounded and described as follows:

                    Northerly by the Southerly line of Main Street,  two hundred
                    seventy-one and 37/100 feet;

                    Southeasterly  by the  Northwesterly  line of the Esplanade,
                    one hundred thirty and 39/100 feet;

                    Southwesterly  by land now or formerly of George C. Crocker,
                    et al., Trustees, one hundred seventy-eight and 68/100 feet;
                    and

         Westerly  by Lot E as shown on plan  hereinafter  mentioned,  eight and
83/100 feet (Lot E being part of the second registered parcel below identified).

         The  second  registered  parcel is that  shown on Land Court Plan 6615B
filed with the  Certificate  filed in  Registration  Book 60,  Page 301.  in the
Middlesex  South Registry  District of the Land Court,  bounded and described as
follows:

                    Northerly by the Southerly line of Main Street,  two hundred
                    and thirty feet;

         Easterly, seventy-two and 28/100 feet;

                    Southeasterly,  two hundred and 70/100 feet,  by land now or
                    formerly of Frederick D. Fisk, et al., Trustees;

                    Southerly by land now or formerly of Arthur D. Little, Inc.,
                    thirty-six and 34/100 feet; and

                    Westerly by other land now or formerly of Frederick D. Fisk,
                    et al, Trustees, one hundred and twenty-five feet.

                    For Mortgagor's title see transfer  Certificate of Title No.
                    170276 and deed  recorded at Middlesex  Registry of Deeds at
                    Book 15494, Page 554.



<PAGE>


                                                     EXHIBIT C

                                        DETERMINATION OF FAIR RENTAL VALUE

         In the event the Fair Rental  Value of the  Additional  Premises or the
Premises  during  any  Additional  Term must be  determined  by  appraisal,  the
determination of Fair Rental value shall be made:

                    (i)  by  an  appraiser  chosen  by  agreement   between  the
                         parties; or

                    (ii) if the parties  shall not agree on an appraiser  within
                         thirty (30) days after the period for agreement on Fair
                         Rental  Value has  elapsed,  by taking  the  arithmetic
                         average of the value assigned by three appraisers,  one
                         selected by each of the parties, and the third selected
                         by  agreement  of  the  two   appraisers  so  selected;
                         provided  that, if the appraised  value assigned by any
                         appraiser selected by a party shall be less than ninety
                         percent  (90%),  or more than one  hundred  ten percent
                         (110 %) of the  appraised  value  assigned by the third
                         appraiser, then such first value shall, for purposes of
                         this subparagraph, be increased to ninety percent (90%)
                         or  decreased  to one hundred  ten percent  (110 %), as
                         applicable,  of the  appraised  value  assigned by such
                         third  appraiser.  All  appraisers  referred to in this
                         Exhibit  shall be  M.A.I.  appraisers  with at least 10
                         years of experience  appraising  commercial real estate
                         in the greater Boston area. The costs of each appraiser
                         shall be borne by the party  appointing  him, or in the
                         case of a third  appraiser,  shall be shared equally by
                         the  parties.  In the event that either  party fails to
                         appoint  an  appraiser  pursuant  to this  subparagraph
                         within  thirty (30) days after the period for agreement
                         of Fair Rental Value has elapsed,  then the  appraiser,
                         if any,  appointed by the other parties  shall,  acting
                         singularly,  make  the  determination  of  Fair  Rental
                         Value.  If the two appraisers  appointed by the parties
                         do not within a period of  fifteen  (15) days after the
                         appointment  of the  later  of  them,  appoint  a third
                         appraiser  willing  so to act,  then  either  party may
                         designate instead that the third appraiser be appointed
                         by the American  Arbitration  Association  (pursuant to
                         its then applicable rules) or a successor  organization
                         thereto (unless any party or business associate thereof
                         holds  such a  position,  in  which  event  said  third
                         appraiser  shall be appointed by the person holding the
                         next  highest  position  on  said  Board  who  is not a
                         business  associate of any party) and the individual so
                         appointed shall for all purposes have the same standing
                         and powers as though he had been  seasonably  appointed
                         by the appraisers first appointed. The appraisers shall
                         be  instructed  that  the  foregoing  appraisals  shall
                         reflect any anticipated  increase in the rental payable
                         between  the  date of the  appraisers,  report  and the
                         first day of the extended term and that in  determining
                         the same they may (but need not) take into  account any
                         appropriate nationally recognized consumer Price Index.
                         Such  appraisals  shall also take into account the fact
                         that the  portion  of the rental  subject to  appraisal
                         which is  included  in Tenants  Included  Share of Real
                         Estate  Taxes and  Operating  Expenses  (referred to on
                         page 3  above)  by  their  own  terms  are  subject  to
                         increase. The appraisers shall also considers all other
                         relevant   factor  .  No  rental   increase   shall  be
                         attributable  to the  value of or the  right to use any
                         improvements  paid for by Tenant (and not reimbursed by
                         Landlord) and installed after  commencement of the term
                         of the Prior Lease. Each appraiser  appointed hereunder
                         shall acknowledge in writing an obligation hereunder to
                         reach a  decision  no later  than 30 days  after  their
                         appointment.

<PAGE>


                                                     EXHIBIT D

                                               INTENTIONALLY DELETED



<PAGE>


                                                     EXHIBIT E

                                               INTENTIONALLY DELETED



<PAGE>


                                                     EXHIBIT F

                                               INTENTIONALLY DELETED