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                                                                    Exhibit 4.15


                                SIXTH AMENDMENT

                                      TO

                          SECOND AMENDED AND RESTATED

                       AGREEMENT OF LIMITED PARTNERSHIP

                                      OF

                       CABOT INDUSTRIAL PROPERTIES, L.P.

     THIS SIXTH AMENDMENT TO SECOND AMENDED AND RESTATED AGREEMENT OF LIMITED
PARTNERSHIP (this "Amendment") dated as of March 23, 1999, is entered into by
CABOT INDUSTRIAL TRUST, a Maryland real estate investment trust, as general
partner (the "General Partner") of CABOT INDUSTRIAL PROPERTIES, L.P. (the
"Partnership"), for itself and on behalf of the limited partners of the
Partnership, and J.P. MORGAN EMERGING TECHNOLOGY EXCHANGE FUND, LLC, a Delaware
limited liability company ("Contributor").

     WHEREAS, Section 4.2(a) of the Second Amended and Restated Agreement of
Limited Partnership of the Partnership (the "Partnership Agreement") authorizes
the General Partner to cause the Partnership to issue additional Partnership
Units in one or more classes or series, with such designations, preferences and
relative, participating, optional or other special rights, powers and duties as
shall be determined by the General Partner, subject to the provisions of such
section; and

     WHEREAS, pursuant to the authority granted to the General Partner pursuant
to Sections 4.2(a) and 14.1(b) of the Partnership Agreement, the General Partner
desires to amend the Partnership Agreement (i) to establish a new class of
Partnership Units, the Series G Preferred Units (as hereinafter defined), and to
set forth the designations, rights, powers, preferences and duties of such
Series G Preferred Units, (ii) to issue the Series G Preferred Units to
Contributor and admit Contributor as an Additional Limited Partner and (iii) to
make certain other changes to the Partnership Agreement.

     NOW, THEREFORE, in consideration of good and valuable consideration, the
receipt and sufficiency of which hereby are acknowledged, the General Partner
hereby amends the Partnership Agreement as follows:

          Section 1. Definitions. For purposes of this Amendment, the term
                     -----------
"Parity Preferred Units" shall be used to refer to any class or series of
 ----------------------
Partnership Interests of the Partnership now or hereafter authorized, issued or
outstanding expressly designated by the
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Partnership to rank on a parity with Series G Preferred Units with respect to
distributions and rights upon voluntary or involuntary liquidation, winding-up
or dissolution of the Partnership. The term "Priority Return" shall mean an
                                             ---------------
amount equal to 8.875% per annum, determined on the basis of a 360 day year of
twelve 30 day months, cumulative to the extent not distributed for any given
distribution period pursuant to Section 5.1 of the Partnership Agreement, of the
stated value of $25 per Series G Preferred Unit, commencing on the date of
issuance of such Series G Preferred Unit. The term "Subsidiary" shall mean with
                                                    ----------
respect to any person, any corporation, partnership, limited liability company,
joint venture or other entity of which a majority of(i) voting power of the
voting equity securities or (ii) the outstanding equity interests, is owned,
directly or indirectly, by such person. The term "PTP" shall mean a "publicly
                                                  ---
traded partnership" within the meaning of Section 7704 of the Code. Capitalized
terms used herein and not otherwise defined herein shall have the meanings
ascribed to them in the Partnership Agreement.

          Section 2. Designation and Number. A series of Partnership Units in
                     ----------------------
the Partnership designated as the "8.875% Series G Cumulative Redeemable
Preferred Units" (the "Series G Preferred Units") is hereby established. The
                       ------------------------
number of Series G Preferred Units shall be 600,000.

          Section 3. Distributions. (a) Payment of Distributions. Subject to the
                     -------------      ------------------------
rights of holders of Parity Preferred Units as to the payment of distributions,
pursuant to Section 5.1 of the Partnership Agreement, holders of Series G
Preferred Units shall be entitled to receive, when, as and if declared by the
Partnership acting through the General Partner, out of Available Cash,
cumulative preferential cash distributions at the rate per annum of 8.875% of
the original Capital Contribution per Series G Preferred Unit. Such
distributions shall be cumulative, shall accrue from the original date of
issuance and will be payable (i) quarterly in arrears, on March 25, June 25,
September 25 and December 25 of each year commencing on June 25, 2000 and, (ii),
in the event of (A) an exchange of Series G Preferred Units into Series G
Preferred Shares (as hereinafter defined), or (B) a redemption of Series G
Preferred Units, on the exchange date or redemption date, as applicable (each a
"Preferred Unit Distribution Payment Date"). The amount of the distribution
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payable for any period will be computed on the basis of a 360-day year of twelve
30-day months and for any period shorter than a full quarterly period for which
distributions are computed, the amount of the distribution payable will be
computed on the basis of the actual number of days elapsed in such period. If
any date on which distributions are to be made on the Series G Preferred Units
is not a Business Day (as defined herein), then payment of the distribution to
be made on such date will be made on the next succeeding day that is a Business
Day (and without any interest or other payment in respect of any such delay)
except that, if such Business Day is in the next succeeding calendar year, such
payment shall be made on the immediately preceding Business Day, in each case
with the same force and effect as if made on such date. Distributions on the
Series G Preferred Units will be made to the holders of record of the Series G
Preferred Units on the relevant record dates to be fixed by the Partnership
acting through the General Partner, which record dates shall in no event exceed
fifteen (15) Business Days prior to the relevant Preferred Unit Distribution
Payment Date (the "Preferred Unit Partnership Record Date").
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     The term "Business Day" shall mean each day other than a Saturday or a
Sunday, which is not a day on which banking institutions in New York, New York
are authorized or required by law, regulations or executive order to close.

          (b) Distributions Cumulative. Distributions on the Series G Preferred
              ------------------------
Units will accrue whether or not the terms and provisions of any agreement of
the Partnership, including any agreement relating to its indebtedness, at any
time prohibit the current payment of distributions, whether or not the
Partnership has earnings, whether or not there are funds legally available for
the payment of such distributions and whether or not such distributions are
authorized. Accrued but unpaid distributions on the Series G Preferred Units
will accumulate as of the Preferred Unit Distribution Payment Date on which they
first become payable. Distributions on account of arrears for any past
distribution periods may be declared and paid at any time, without reference to
a regular Preferred Unit Distribution Payment Date to holders of record of the
Series G Preferred Units on the record date fixed by the Partnership acting
through the General Partner, which date shall not exceed fifteen (15) Business
Days prior to the payment date. Accumulated and unpaid distributions will not
bear interest.

          (c) Priority as to Distributions. (i) So long as any Series G
              ----------------------------
Preferred Units are outstanding, no distribution of cash or other property shall
be authorized, declared, paid or set apart for payment on or with respect to any
class or series of Partnership Interests of the Partnership ranking junior as to
the payment of distributions or rights upon a voluntary or involuntary
liquidation, dissolution or winding-up of the Partnership to the Series G
Preferred Units (collectively, "Junior Units"), nor shall any cash or other
                                ------------
property be set aside for or applied to the purchase, redemption or other
acquisition for consideration of any Series G Preferred Units, any Parity
Preferred Units or any Junior Units, unless, in each case, all distributions
accumulated on all Series G Preferred Units and all classes and series of
outstanding Parity Preferred Units have been paid in full. The foregoing
sentence will not prohibit (a) distributions payable solely in Junior Units, (b)
the conversion of Junior Units or Parity Preferred Units into Partnership Units
ranking junior to the Series G Preferred Units as to distributions and upon
liquidation, winding-up or dissolution or (c) the redemption of Partnership
Interests corresponding to any Series G Preferred Shares (as hereinafter
defined), Parity Preferred Shares (as such term is defined in the Declaration of
Trust of the General Partner, as supplemented (the "Charter")), or Junior Shares
                                                    -------
(as such term is defined in the Charter) to be purchased by the General Partner
pursuant to Article 3 of the Charter to preserve the General Partner's status as
a real estate investment trust, provided that such redemption shall be upon the
same terms as the corresponding purchase pursuant to Article 3 of the Charter.

          (ii) So long as distributions have not been paid in full (or a sum
     sufficient for such full payment is not irrevocably deposited in trust for
     payment) upon the Series G

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     Preferred Units, all distributions authorized and declared on the Series G
     Preferred Units and all classes or series of outstanding Parity Preferred
     Units shall be authorized and declared so that the amount of distributions
     authorized and declared per Series G Preferred Unit and such other classes
     or series of Parity Preferred Units shall in all cases bear to each other
     the same ratio that accrued distributions per Series G Preferred Unit and
     such other classes or series of Parity Preferred Units (which shall not
     include any accumulation in respect of unpaid distributions for prior
     distribution periods if such class or series of Parity Preferred Units do
     not have cumulative distribution rights) bear to each other.

          (d) No Further Rights. Holders of Series G Preferred Units shall not
              -----------------
be entitled to any distributions, whether payable in cash, other property or
otherwise, in excess of the full cumulative distributions described herein.

     Section 4. Liquidation Proceeds. (a) Upon voluntary or involuntary
                --------------------
liquidation, dissolution or winding-up of the Partnership, distributions on the
Series G Preferred Units shall be made in accordance with Section 13.2 of the
Partnership Agreement.

          (b) Notice. Written notice of any such voluntary or involuntary
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liquidation, dissolution or winding-up of the Partnership, stating the payment
date or dates when, and the place or places where, the amounts distributable in
such circumstances shall be payable, shall be given by (i) fax and (ii) by first
class mail, postage pre-paid, not less than thirty (30) and not more than sixty
(60) days prior to the payment date stated therein, to each record holder of the
Series G Preferred Units at the respective addresses of such holders as the same
shall appear on the transfer records of the Partnership.

          (c) No Further Rights. After payment of the full amount of the
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liquidating distributions to which they are entitled, the holders of Series G
Preferred Units will have no right or claim to any of the remaining assets of
the Partnership.

          (d) Consolidation, Merger or Certain Other Transactions. The voluntary
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sale, conveyance, lease, exchange or transfer (for cash, shares of stock,
securities or other consideration) of all or substantially all of the property
or assets of the General Partner to, or the consolidation or merger or other
business combination of the Partnership with or into, any corporation, trust,
partnership, limited liability company or other entity (or of any corporation,
trust, partnership, limited liability company or other entity with or into the
Partnership) shall not be deemed to constitute a liquidation, dissolution or
winding-up of the Partnership.

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     Section 5. Optional Redemption. (a) Right of Optional Redemption. The
                -------------------      ----------------------------
Series G Preferred Units may not be redeemed prior to the fifth (5th)
anniversary of the issuance date. On or after such date, the Partnership shall
have the right to redeem the Series G Preferred Units, in whole or in part, at
any time or from time to time, upon not less than thirty (30) nor more than
sixty (60) days' written notice, at a redemption price, payable in cash, equal
to the Capital Account balance of the holders of Series G Preferred Units (the
"Redemption Price"); provided, however, that no redemption pursuant to this
 ----------------
Section 5 will be permitted if the Redemption Price does not equal or exceed the
original Capital Contribution of such holder plus the cumulative Priority
Return, whether or not declared, to the redemption date to the extent not
previously distributed pursuant to Section 3(a). If fewer than all of the
outstanding Series G Preferred Units are to be redeemed, the Series G Preferred
Units to be redeemed shall be selected pro rata (as nearly as practicable
without creating fractional units).

          (b) Limitation on Redemption. The Partnership may not redeem fewer
              ------------------------
than all of the outstanding Series G Preferred Units unless all accumulated and
unpaid distributions have been paid on all Series G Preferred Units for all
quarterly distribution periods terminating on or prior to the date of
redemption.

          (c) Procedures for Redemption. (i) Notice of redemption will be (A)
              -------------------------
faxed, and (B) mailed by the Partnership, by certified mail, postage prepaid,
not less than thirty (30) nor more than sixty (60) days prior to the redemption
date, addressed to the respective holders of record of the Series G Preferred
Units at their respective addresses as they appear on the records of the
Partnership. No failure to give or defect in such notice shall affect the
validity of the proceedings for the redemption of any Series G Preferred Units
except as to the holder to whom such notice was defective or not given. In
addition to any information required by law, each such notice shall state: (1)
the redemption date, (2) the Redemption Price, (3) the aggregate number of
Series G Preferred Units to be redeemed and if fewer than all of the outstanding
Series G Preferred Units are to be redeemed, the number of Series G Preferred
Units to be redeemed held by such holder, which number shall equal such holder's
pro rata share (based on the percentage of the aggregate number of outstanding
Series G Preferred Units the total number of Series G Preferred Units held by
such holder represents) of the aggregate number of Series G Preferred Units to
be redeemed, (4) the place or places where such Series G Preferred Units are to
be surrendered for payment of the Redemption Price, (5) that distributions on
the Series G Preferred Units to be redeemed will cease to accumulate on such
redemption date and (6) that payment of the Redemption Price will be made upon
presentation and surrender of such Series G Preferred Units.

          (ii) If the Partnership gives a notice of redemption in respect of
     Series G Preferred Units (which notice will be irrevocable) then, by 12:00
     noon, New York City time, on the redemption date, the Partnership will
     deposit irrevocably in trust for the benefit of the

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     Series G Preferred Units being redeemed funds sufficient to pay the
     applicable Redemption Price and will give irrevocable instructions and
     authority to pay such Redemption Price to the holders of the Series G
     Preferred Units upon surrender of the Series G Preferred Units by such
     holders at the place designated in the notice of redemption. If the Series
     G Preferred Units are evidenced by a certificate and if fewer than all
     Series G Preferred Units evidenced by any certificate are being redeemed, a
     new certificate shall be issued upon surrender of the certificate
     evidencing all Series G Preferred Units, evidencing the unredeemed Series G
     Preferred Units without cost to the holder thereof. On and after the date
     of redemption, distributions will cease to accumulate on the Series G
     Preferred Units or portions thereof called for redemption, unless the
     Partnership defaults in the payment thereof. If any date fixed for
     redemption of Series G Preferred Units is not a Business Day, then payment
     of the Redemption Price payable on such date will be made on the next
     succeeding day that is a Business Day (and without any interest or other
     payment in respect of any such delay) except that, if such Business Day
     falls in the next calendar year, such payment will be made on the
     immediately preceding Business Day, in each case with the same force and
     effect as if made on such date fixed for redemption. If payment of the
     Redemption Price is improperly withheld or refused and not paid by the
     Partnership, distributions on such Series G Preferred Units will continue
     to accumulate from the original redemption date to the date of payment, in
     which case the actual payment date will be considered the date fixed for
     redemption for purposes of calculating the applicable Redemption Price.

     Section 6. Voting Rights. (a) General. Holders of the Series G Preferred
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Units will not have any voting rights or right to consent to any matter
requiring the consent or approval of the Limited Partners, except as set forth
in the Partnership Agreement and except as set forth below. In the event of a
conflict between the terms of this Section 6 and any other terms of this
Amendment, the terms of this Section 6 shall control.

          (b) Certain Voting Rights. So long as any Series G Preferred Units
              ---------------------
remain outstanding, the Partnership shall not, without the affirmative vote of
the holders of at least two-thirds of the Series G Preferred Units outstanding
at the time (i) authorize or create, or increase the authorized or issued amount
of, any class or series of Partnership Interests senior to the Series G
Preferred Units with respect to payment of distributions or rights upon
liquidation, dissolution or winding-up of the Partnership or reclassify any
Partnership Interests of the Partnership into any such senior Partnership
Interests, or create, authorize or issue any obligations or security convertible
into or evidencing the right to purchase any such senior Partnership Interests,
(ii) authorize or create, or increase the authorized or issued amount of any
Parity Preferred Units or reclassify any Partnership Interest into any such
Partnership Interest or create, authorize or issue any obligations or security
convertible into or evidencing the right to purchase any such Partnership
Interests but only to the extent such Parity Preferred Units are issued to an
Affiliate of the Partnership, other than the General Partner to the extent the
issuance of such interests was to allow the General Partner to issue
corresponding preferred stock to persons who are not Affiliates of the
Partnership (or to Affiliates

                                       6
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purchasing the preferred stock on the same terms as non-affiliated purchasers)
or (iii) either (A) consolidate, merge into or with, or convey, transfer or
lease all or substantially all of its assets to, any corporation or other entity
or (B) amend, alter or repeal the provisions of the Partnership Agreement
whether by merger, consolidation or otherwise, that would materially and
adversely affect the powers, special rights, preferences, privileges or voting
power of the Series G Preferred Units or the holders thereof; provided, however,
that with respect to the occurrence of a merger, consolidation or a sale or
lease of all or substantially all of the Partnership's assets as an entirety, so
long as (1) the Partnership is the surviving entity and the Series G Preferred
Units remain outstanding with the terms thereof unchanged, or (2) the resulting,
surviving or transferee entity is a partnership, limited liability company or
other pass-through entity organized under the laws of any state and substitutes
the Series G Preferred Units for other interests in such entity having
substantially the same terms and rights as the Series G Preferred Units,
including with respect to distributions, voting rights and rights upon
liquidation, dissolution or winding-up of such entity, then the occurrence of
any such event shall not be deemed to materially and adversely affect such
rights, privileges or voting powers of the holders of the Series G Preferred
Units and no vote of the Series G Preferred Units shall be required in such
case; and provided further that any increase in the amount of Partnership
Interests or the creation or issuance of any other class or series of
Partnership Interests, in each case ranking (y) junior to the Series G Preferred
Units with respect to payment of distributions or the distribution of assets
upon liquidation, dissolution or winding-up of the Partnership, or (z) on a
parity with the Series G Preferred Units with respect to payment of
distributions and the distribution of assets upon liquidation, dissolution or
winding-up of the Partnership to the extent such Partnership Interests are not
issued to an Affiliate, other than the General Partner to the extent the
issuance of such interests was to allow the General Partner to issue
corresponding preferred stock to persons who are not Affiliates, shall not be
deemed to materially and adversely affect such rights, preferences, privileges
or voting powers and no vote of the Series G Preferred Units shall be required
in such case.

     Section 7. Transfer Restrictions. The Series G Preferred Units shall be
                ---------------------
subject to the provisions of Article XI of the Partnership Agreement, provided,
however, that (i) the General Partner shall act reasonably in exercising its
discretion pursuant to the provisions of Section 11.4(a)(ii) with respect to
transferees of Series G Preferred Units, (ii) the provisions of Clause B of
Section 11.3(d) shall not be applicable to holders of Series G Preferred Units
if at the time of such transfer, the Partnership already has 100 Partners; (iii)
if only a portion of the Series G Preferred Units shall be transferred, the
transferee of such transferred Series G Preferred Units shall, subject to the
provisions of Section 11.4, be substituted as a Limited Partner in place of the
transferring holders only as to the Series G Preferred Units so transferred; and
(iv) the provisions of Sections 11.6(c) and 11.6(d) shall not be applicable to
any transfer of Series G Preferred Units; and provided further that "transfer"
when used in Article XI shall not be deemed to include any exchange pursuant to
Section 8 below.

     Section 8. Exchange Rights. (a) Right to Exchange.
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          (i) Series G Preferred Units will be exchangeable in whole or in part
     at anytime on or after the tenth (10th) anniversary of the date of
     issuance, at the option of the holders thereof, for authorized but
     previously unissued shares of 8.875% Series G Cumulative Redeemable
     Preferred Shares of the General Partner (the "Series G Preferred Shares")
                                                   -------------------------
     at an exchange rate of one Series G Preferred Share for one Series G
     Preferred Unit, subject to adjustment as described below (the "Exchange
                                                                    --------
     Price"), provided that the Series G Preferred Units will become
     -----
     exchangeable at any time, in whole or in part, at the option of the holders
     of Series G Units, for Series G Preferred Shares if (y) at any time full
     distributions shall not have been timely made on any Series G Preferred
     Unit with respect to six (6) prior quarterly distribution periods, whether
     or not consecutive; provided, however, that a distribution in respect of
     Series G Preferred Units shall be considered timely made if made within two
     (2) Business Days after the applicable Preferred Unit Distribution Payment
     Date if at the time of such late payment there shall not be any prior
     quarterly distribution periods in respect of which full distributions were
     not timely made or (z) upon receipt by a holder or holders of Series G
     Preferred Units of (1) a notice from the General Partner that the General
     Partner or a Subsidiary of the General Partner has taken the position that
     the Partnership is, or upon the occurrence of a defined event in the
     immediate future will be, a PTP and (2) an opinion rendered by an outside
     nationally recognized independent counsel familiar with such matters
     addressed to a holder or holders of Series G Preferred Units, that the
     Partnership is or likely is, or upon the occurrence of a defined event in
     the immediate future will be or likely will be, a PTP. In addition, the
     Series G Preferred Units may be exchanged for Series G Preferred Shares, in
     whole or in part, at the option of any holder prior to the tenth (10th)
     anniversary of the issuance date and after the third (3rd) anniversary
     thereof if such holder of a Series G Preferred Units shall deliver to the
     General Partner either (i) a private letter ruling addressed to such holder
     of Series G Preferred Units or (ii) an opinion of independent counsel
     reasonably acceptable to the General Partner based on the enactment of a
     statute, temporary or final Treasury Regulations or the publication of a
     Revenue Ruling, in either case to the effect that an exchange of the Series
     G Preferred Units at such earlier time would not cause the Series G
     Preferred Units to be considered "stock or securities" within the meaning
     of Section 351(e) of the Code for purposes of determining whether the
     holder of such Series G Preferred Units is an "investment company" under
     Section 721(b) of the Code if an exchange is permitted at such earlier
     date. Furthermore, all the Series G Preferred Units, held by any holder
     thereof which is a real estate investment trust within the meaning of
     Sections 856 through 859 of the Code for Series G Preferred Shares may be
     exchanged in whole but not in part (but only if the exchange may be
     accomplished consistently with the ownership limitations set forth under
     Article 3 of the Charter (taking into account exceptions thereto)) if at
     any time, (I) the Partnership reasonably determines that the assets and
     income of the Partnership for a taxable year after 1999 would not satisfy
     the income and assets tests of Section 856 of the Code for such taxable
     year if the Partnership were a real estate investment trust within the
     meaning of the Code or (ii) any such holder of Series G Preferred Units
     shall deliver to the Partnership and the General Partner an opinion of
     independent counsel reasonably acceptable to the General Partner to the
     effect that, based on the assets and income of the Partnership for a
     taxable year

                                       8
<PAGE>

     after 1999, the Partnership would not satisfy the income assets tests of
     Section 856 of the Code for such taxable year if the Partnership were a
     real estate investment trust within the meaning of the Code and that such
     failure would create a meaningful risk that a holder of the Series G
     Preferred Units would fail to maintain qualification as a real estate
     investment trust.

          (ii) Notwithstanding anything to the contrary set forth in Section
     8(a)(i) hereof, if an Exchange Notice (as defined herein) has been
     delivered to the General Partner, then the General Partner may, at its
     option, elect to redeem or cause the Partnership to redeem all or a portion
     of the outstanding Series G Preferred Units for cash in an amount equal to
     the original Capital Contribution per Series G Preferred Unit and all
     accrued and unpaid distributions thereon to the date of redemption. The
     General Partner may exercise its option to redeem the Series G Preferred
     Units for cash pursuant to this Section 8(a)(ii) hereof by giving each
     holder of record of Series G Preferred Units notice of its election to
     redeem for cash, within ten (10) Business Days after receipt of the
     Exchange Notice, by (y) fax, and (z) registered mail, postage paid, at the
     address of each holder as it may appear on the records of the Partnership
     stating (A) the redemption date, which shall be no later than sixty (60)
     days following the receipt of the Exchange Notice, (B) the redemption
     price, (C) the place or places where the Series G Preferred Units are to be
     surrendered for payment of the redemption price, (D) that distributions on
     the Series G Preferred Units will cease to accrue on such redemption date;
     (E) that payment of the redemption price will be made upon presentation and
     surrender of the Series G Preferred Units and (F) the aggregate number of
     Series G Preferred Units to be redeemed, and if fewer than all of the
     outstanding Series G Preferred Units are to be redeemed, the number of
     Series G Preferred Units to be redeemed held by such holder, which number
     shall equal such holder's pro-rata share (based on the percentage of the
     aggregate number of outstanding Series G Preferred Units the total number
     of Series G Preferred Units held by such holder represents) of the
     aggregate number of Series G Preferred Units being redeemed.

          (iii) In the event an exchange of all or a portion of Series G
     Preferred Units pursuant to Section 8(a)(i) hereof would violate the
     provisions on ownership limitation of the General Partner set forth in
     Article 3 of the Charter with respect to the Series G Preferred Shares, the
     General Partner shall give written notice thereof to each holder of record
     of Series G Preferred Units, within ten (10) Business Days following
     receipt of the Exchange Notice, by (y) fax, and (z) registered mail,
     postage prepaid, at the address of each such holder set forth in the
     records of the Partnership. In such event, each holder of Series G
     Preferred Units shall be entitled to exchange, pursuant to the provision of
     Section 8(b) a number of Series G Preferred Units which would comply with
     the provisions on the ownership limitation of the General Partner set forth
     in such Article 3 of the Charter and any Series G Preferred Units not so
     exchanged (the "Excess Units") shall be redeemed by the Partnership for
                     ------------
     cash in an amount equal to the original Capital Contribution per Excess
     Unit, plus any accrued and unpaid distributions thereon, whether or not
     declared, to the date of

                                       9
<PAGE>

     redemption. The written notice of the General Partner shall state (A) the
     number of Excess Units held by such holder, (B) the redemption price of the
     Excess Units, (C) the date on which such Excess Units shall be redeemed,
     which date shall be no later than sixty (60) days following the receipt of
     the Exchange Notice, (D) the place or places where such Excess Units are to
     be surrendered for payment of the Redemption Price, (E) that distributions
     on the Excess Units will cease to accrue on such redemption date, and (F)
     that payment of the redemption price will be made upon presentation and
     surrender of such Excess Units. In the event an exchange would result in
     Excess Units, as a condition to such exchange, each holder of such units
     agrees to provide representations and covenants reasonably requested by the
     General Partner relating to (1) the widely held nature of the interests in
     such holder, sufficient to assure the General Partner that the holder's
     ownership of stock of the General Partner (without regard to the limits
     described above) will not cause any individual to Beneficially Own in
     excess of the Ownership Limit (all as defined in the General Partner's
     Charter); and (2) to the extent such holder can so represent and covenant
     without obtaining information from its owners, the holder's ownership of
     tenants of the Partnership and its affiliates.

          (iv) The redemption of Series G Preferred Units described in Section
     8(a)(ii) and (iii) shall be subject to the provisions of Sections 5(b) and
     5(c)(ii); provided, however, that the term "Redemption Price" in such
               --------  -------
     section shall be read to mean the original Capital Contribution per Series
     G Preferred Unit being redeemed plus all accrued and unpaid distributions
     to the redemption date.

          (b) Procedure for Exchange.
              ----------------------

          (i) Any exchange pursuant to this Amendment shall be exercised
     pursuant to a notice of exchange (the "Exchange Notice") delivered to the
                                            ---------------
     General Partner by the holder who is exercising such exchange right, by (A)
     fax and (B) by certified mail postage prepaid. The exchange of Series G
     Preferred Units, or a specified portion thereof, may be effected after the
     fifth (5th) Business Day following receipt by the General Partner of the
     Exchange Notice by delivering certificates, if any, representing such
     Series G Preferred Units to be exchanged together with, if applicable,
     written notice of exchange and a proper assignment of such Series G
     Preferred Units to the office of the General Partner maintained for such
     purpose. Currently, such office is Two Center Plaza, Suite 200, Boston,
     Massachusetts 02108. Each exchange will be deemed to have been effected
     immediately prior to the close of business on the date on which such Series
     G Preferred Units to be exchanged (together with all required
     documentation) shall have been surrendered and notice shall have been
     received by the General Partner as aforesaid and the Exchange Price shall
     have been paid. Any Series G Preferred Shares issued pursuant to this
     Section 8 shall be delivered as shares which are duly authorized, validly
     issued, fully paid and nonassessable, free of pledge, lien, encumbrance or
     restriction other than those provided in the Charter, the Bylaws of the
     General Partner, the Securities Act of 1933 and relevant state securities
     or blue sky laws.

                                      10
<PAGE>

          (ii) In the event of an exchange of Series G Preferred Units for
     Series G Preferred Shares, an amount equal to the accrued and unpaid
     distributions, whether or not declared, to the date of exchange on any
     Series G Preferred Units tendered for exchange shall (A) accrue on the
     Series G Preferred Shares into which such Series G Preferred Units are
     exchanged, and (B) continue to accrue on such Series G Preferred Units,
     which shall remain outstanding following such exchange, with the General
     Partner as the holder of such Series G Preferred Units. Notwithstanding
     anything to the contrary set forth herein, in no event shall a holder of a
     Series G Preferred Unit that was validly exchanged into Series G Preferred
     Shares pursuant to this section (other than the General Partner now holding
     such Series G Preferred Unit), receive a cash distribution out of Available
     Cash of the Partnership, if such holder, after exchange, is entitled to
     receive a distribution out of Available Cash with respect to the Series G
     Preferred Shares for which such Series G Preferred Unit was exchanged or
     redeemed.

          (iii) Fractional shares of Series G Preferred Shares are not to be
     issued upon exchange but, in lieu thereof, the General Partner will pay a
     cash adjustment based upon the fair market value of the Series G Preferred
     Shares on the day prior to the exchange date as determined in good faith by
     the Board of Directors of the General Partner.

          (c) Adjustment of Exchange Price.
              ----------------------------

          (i) The Exchange Price is subject to adjustment upon certain events,
     including (a) subdivisions, combinations and reclassifications of the
     Series G Preferred Shares and (b) distributions to all holders of Series G
     Preferred Shares of evidences of indebtedness of the General Partner or
     assets (including securities but excluding dividends and distributions paid
     out of equity applicable to Series G Preferred Shares).

          (ii) In case the General Partner shall be a party to any transaction
     (including, without limitation, a merger, consolidation, statutory share
     exchange, tender offer for all or substantially all of the General
     Partner's capital stock or sale of all or substantially all of the General
     Partner's assets), in each case as a result of which the Series G Preferred
     Shares will be converted into the right to receive shares of capital stock,
     other securities or other property (including cash or any combination
     thereof), each Series G Preferred Unit will thereafter be exchangeable into
     the kind and amount of shares of capital stock and other securities and
     property receivable (including cash or any combination thereof) upon the
     consummation of such transaction by a holder of that number of Series G
     Preferred Shares or fraction thereof into which one Series G Preferred Unit
     was exchangeable immediately prior to such transaction. The General Partner
     may not become a party to any such transaction unless the terms thereof are
     consistent with the foregoing.

                                      11
<PAGE>

     Section 9. No Conversion Rights. (a) The holders of the Series G Preferred
                --------------------
Units shall not have any rights to convert such Partnership Units into any other
class of Partnership Interests or any interest in the Partnership;

     (b) The Series G Preferred Units shall not be subject to the provisions of
Section 4.2(e) of the Partnership Agreement.

     Section 10. No Sinking Fund. No sinking fund shall be established for the
                 ---------------
retirement or redemption of the Series G Preferred Units.

     Section 11. Admission of Limited Partner; Exhibits to Partnership
                 -----------------------------------------------------
Agreement. In accordance with Section 12.2(b), Contributor is hereby admitted as
---------
an Additional Limited Partner. In order to duly reflect the issuance of Series G
Preferred Units provided for herein, the Partnership Agreement will be amended
by deleting Exhibit A attached thereto and substituting Exhibit A attached
                                                        ---------
hereto therefor.

     Section 12. Reaffirmation. Except as modified herein, all terms and
                 -------------
conditions of the Partnership Agreement shall remain in full force and effect,
which terms and conditions the General Partner hereby ratifies and affirms.

                                      12
<PAGE>

IN WITNESS WHEREOF, this Amendment has been executed as of the date first above
written.

                                            CABOT INDUSTRIAL TRUST

                                            By: /s/ Neil Waisnor
                                                ------------------------------
                                            Name: Neil Waisnor
                                            Title:  Senior Vice President

                    ***Signatures Continued On Next Page***
<PAGE>

                                  J.P. MORGAN EMERGING TECHNOLOGY
                                  EXCHANGE FUND, LLC

                                  By: J.P. Morgan Private Investments Inc., as
                                      manager of J.P. Morgan Emerging Technology
                                      Exchange Fund, LLC

                                  By: /s/ Gerald R. Ronayne
                                      ----------------------------------------
                                            Name: Gerald R. Ronayne
                                            Title: Director
                                      Address:  345 Park Avenue
                                                New York, New York 10154-1002
                                                Attention: Andrew Craighead