Exhibit 10.25


                         FOURTH AMENDMENT OF LEASE

     THIS AMENDMENT, made and entered into as of May 22, 1996, by and between 
WEST VALLEY BUSINESS TRUST ("Landlord") and INFONAUTICS CORPORATION, a 
Pennsylvania corporation ("Tenant").

     WHEREAS, by lease dated June, 1994, as amended January, 1995, June 30, 
1995, and November 13, 1995 (the "Lease"), Landlord leased to Tenant and 
Tenant leased from Landlord portions of buildings 900, 1000 and 1100 located 
at 900 West Valley Road, Wayne, Pennsylvania;

     WHEREAS, the parties desire to amend the Lease to provide for conduit 
access for telecommunication services to the Demised Premises at the request 
of and for the benefit of Tenant.

     NOW THEREFORE, in consideration of the sum of $1.00, in hand well and 
truly paid, and other good and valuable consideration, the receipt of which 
is hereby acknowledged, and in further consideration of the mutual premises 
and convenants herein contained, the parties, intending to be legally bound, 
agree:

          1.    Landlord shall enter into the Utility Access Agreement with 
Metropolitan Fiber Systems of Philadelphia, Inc. (the "Access Agreement"), in 
substantially the form attached to this Amendment.

          2.    Any costs or expense incurred by Landlord with respect to the 
Access Agreement not promptly paid by the licensee under the Access Agreement 
shall be paid by Tenant to Landlord as additional rent under the Lease.

          3.    Tenant shall indemnify and hold Landlord harmless from any 
cost or expense, including but not limited to reasonable attorneys fees, 
arising in connection with the Access Agreement.

          4.    Except as modified herein, all terms and conditions of the 
Lease, including but not limited to provisions providing for confession of 
judgment, shall remain in full force and effect.



     IN WITNESS WHEREOF, the parties have hereunto set their hands and seals 
on the date first above mentioned.     

                                       LANDLORD:

                                           WEST VALLEY BUSINESS TRUST

                                           By:  /s/ Robert W. Zwengler
                                              -----------------------
                                           an officer and not individually



                                       TENANT 

                                           INFONAUTICS CORPORATION, a
                                           Pennsylvania corporation

                                           By:  /s/ Ronald A. Berg
                                              -----------------------
                                              Name:  Ronald A. Berg
                                              Title: Vice President-Finance

                                           Attest:
                                                  -------------------
                                                    [Corporate Seal]   

                                      -2-




                              UTILITY ACCESS AGREEMENT


     This Utility Access Agreement for public utility telecommunications 
services (the "Agreement") is made as of May 22, 1996, between WEST VALLEY 
BUSINESS TRUST, its successors and assigns, with an office in care of Fox 
Realty Company at 1325 Morris Drive, Wayne, PA 19087 ("Licensor"), and 
METROPOLITAN FIBER SYSTEMS OF PHILADELPHIA, INC., a Delaware Corporation (a 
public utility certified and regulated by the State of Delaware and regulated 
by the Federal Communications Commission), its successors and assigns, with 
an office at 1601 Market Street, Suite 2200, Philadelphia, Pennsylvania, 
19103 ("Licensee").

     WHEREAS, Licensor recognizes that Infonautics Corporation has requested 
that Licensee provide public utility telecommunications services to premises 
located in Buildings 900 and 1100 (the "Buildings") located at 900 West 
Valley Drive, leased by Infonautics Corporation from Licensor pursuant to a 
lease entered into with Licensor dated June, 1994, as amended ("the Lease"):

     WHEREAS, a portion of the ground between the Buildings and the MFS 
Backbone is owned by Licensor (the "Property").

     NOW THEREFORE, in consideration of the mutual covenants herein expressed 
and for other good and valuable consideration, the receipt and sufficiency of 
which are hereby acknowledged, Licensee and Licensor hereby covenant and 
agree as follows:

     1.   LICENSEE

          a.    Following notice to and approval of Licensor, as set forth 
                in Paragraph 3, Licensee shall have a license to cross the 
                Property over the route designated on the plan attached 
                hereto as Exhibit "A" (the "Plan") to gain access to the 
                Buildings and the right to construct, where necessary and 
                at its expense, conduit facilities in accordance with the 
                Plan ("the Conduit"), associated with providing public 
                utility telecommunications services (the "License").

          b.    The License granted herein is not exclusive. Licensor hereby
                reserves the right to grant, renew or extend similar licenses
                to others.

          c.    Nothing contained herein shall be constructed as a 
                representation or warranty to Licensee that Licensor is the 
                owner of all of the land over which the Conduit is routed as 
                depicted on the Plans or granting to Licensee any property or
                ownership rights in the Property or the Buildings or as 
                creating a partnership or joint venture between Licensor and
                Licensee.







          negligence or willful misconduct. At the termination of this
          Agreement, any conduit not removed within sixty (60) days after the
          expiration of this Agreement shall be deemed the property of the
          Licensor; provided, however, that Licensor may at its election
          remove the Conduit at Licensee's sole cost.

     6.   ACCESS - Licensor shall provide Licensee access to the Property 
          twenty-four (24) hours a day, seven (7) days a week, three hundred
          sixty-five (365) days a year, so that Licensee may perform 
          installation, operation, maintenance, replacement and repair 
          functions all in accordance with Licensor's rules and regulations.
          Access to the Buildings is subject to the rights of Infonautics 
          Corporation, with whom the Licensee shall make its own 
          arrangements.

     7.   TERM - The term of the License shall be co-terminus with the 
          Infonautics Lease, provided that Licensor may terminate this 
          License pursuant to Section 13.

     8.   INDEMNIFICATION - Licensee shall indemnify, exonerate and hold 
          Licensor, its principals, officers, directors, agents, employees 
          and servants harmless from and against any loss, cost, damage and 
          expense of whatever kind (with the exception of special, 
          consequential and incidental damages) arising directly or 
          indirectly from the construction, operation, maintenance and repair
          of Licensee's Conduit or from Licensee's breach of this Agreement,
          including, but not limited to, reasonable attorney's fees and 
          court costs, except to the extent such loss, damage, cost or 
          expense is due to the gross negligence or willful misconduct of 
          Licensor or its employees, agents or invitees. The provisions of 
          this Section 8 shall survive termination of this Agreement.

     9.   INSURANCE

          a.    Licensee shall maintain such insurance, including through a 
                blanket policy as will fully protect both Licensee and 
                Licensor from any and all claims by employees of Licensee
                under the workmen's compensation act or employers' liability 
                laws, including any employers' disability insurance laws, 
                and from any and all other claims of whatsoever kind or 
                nature for any and all damage to property or for personal 
                injury, including death, to anyone whomsoever, that may arise
                from operations in connection with the performance of their
                services in the Building by Licensee or by anyone directly or
                indirectly engaged or employed by Licensee.  Licensee shall 
                provide Licensor with certificates evidencing the required 
                coverage before Licensee begins any construction work on the 
                Property or in the Buildings. Such policies shall provide 
                that Licensee shall be notified by Licensee's insurance 
                company not less than 30 days in advance of cancellation.



                                       -3-




          b.    Licensee's General Liability insurance shall be a combined 
                single limit of $2,000,000. This policy limit requirement 
                may be increased from time to time by Licensor upon notice to
                Licensee.

          c.    Insurance described in Subsections (a) and (b) of this 
                Section 9 shall be maintained by Licensee throughout the term
                of this Agreement. Upon Licensee's default in obtaining or 
                delivering any such policy or certificate of insurance or 
                Licensee's failure to pay the premiums therefore, Licensor may
                (but shall not be obligated to) secure or pay the premium for 
                any such policy and charge Licensee the cost of such premium.

     10.  LIENS - Licensee shall be responsible for the satisfaction or 
          payment of any liens for any provider of work, labor, material or 
          services claiming by, through or under Licensee. Licensee shall 
          also indemnify, hold harmless and defend Licensor against any such 
          liens, including the reasonable fees of Licensor's attorneys. Such 
          liens shall be discharged by Licensee within thirty (30) days after 
          notice of filing thereof by bonding, payment or otherwise, provided 
          that Licensee may contest, in good faith and by appropriate 
          proceedings any such liens.

     11.  PERFORMANCE OF WORK - Licensee may contract or subcontract any 
          portion of work contemplated by this Agreement to any person or 
          entity competent to perform such work and insured as provided above.
          In no event shall such subcontract relieve Licensee of any of its 
          obligations under this Agreement.

     12.  EVENTS OF DEFAULT - Each of the following occurrences shall 
          constitute an "Event of Default" under this Agreement:

          a.    Breach by either party of any material provision of the 
                Agreement.

          b.    If Licensee abandons or deserts its equipment of the Conduit
                during the Term hereof or Licensee removes its equipment from 
                the Buildings (and does not replace or substitute equipment).

          c.    Interference caused to pre-existing telecommunications 
                facilities by the installation, operation, maintenance, 
                replacement or repair of Licensee's equipment, or the Conduit.

     13.  TERMINATION REMEDIES - Upon occurrence of an Event of Default, the 
          non-defaulting party shall give written notice to the defaulting 
          party, setting forth the nature of the Default. The defaulting party
          shall have thirty (30) days to cure such Default. If the defaulting 
          party shall have failed to cure the 



                                       -4-







          Default within the applicable cure period, the non-defaulting party
          may elect to terminate this Agreement, whereupon Licensee shall 
          remove its equipment and the Conduit from the Property and the 
          Buildings in a neat and orderly manner and as of the date of such 
          removal neither party shall have any claims against the other, 
          except for claims that may have arisen prior to such termination and
          this Agreement shall be deemed terminated and of no force and 
          effect.

     14.  ASSIGNMENT - Licensee shall not assign or transfer this Agreement 
          without the written consent of the Licensor, which consent will not 
          be unreasonably withheld or unduly delayed; except that upon 
          written notice to the Licensor, Licensee may, without obtaining 
          Licensor's prior consent, make such assignment to:

          a.    any firm or corporation which Licensee controls, is controlled
                by or is under common control with;

          b.    any partnership in which Licensee has a controlling interest;
                or

          c.    to any entity which succeeds to all or substantially all of 
                Licensor's assets whether by merger, sale or otherwise, 
                provided that the assignee assumes in full the obligation of 
                Licensee under this Agreement.

     15.  NOTICE - Every notice required or permitted hereunder shall be in 
          writing and shall be deemed to have been duly given three (3) 
          business days after mailed by certified or registered mail, return
          receipt requested, to the party's address set forth in the 
          introductory paragraph of the Agreement. Either party may change 
          its address for the purpose of notice hereunder by providing the 
          other party with notice of the new address.

     16.  GOVERNING LAW - This Agreement shall be governed by and construed 
          under the laws of the Commonwealth of Pennsylvania.



                                       -5-







     17.  RECORDING - This Agreement shall not be recorded in any public
          office.

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the date and year first above written.



                                           WEST VALLEY BUSINESS TRUST

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

                                              an officer and not individually



                                           METROPOLITAN FIBER SYSTEMS 
                                           OF PHILADELPHIA, INC.
                                           a Delaware corporation

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

                                           Attest:
                                                  -------------------
                                                    [Corporate Seal]


                                        -6-






Map of
Outside Plant Facility
Proposal-Infonautics
900 West Valley Rd
Ste 900 4/29/96
Dwg 2 of 2






Map of
Outside Plant Facility
Proposal-Infonautics
900 West Valley Rd
Ste 900 4/29/96
Dwg 1 of 2








                            FIFTH AMENDMENT OF LEASE


     THIS AMENDMENT, made and entered into as of April 18, 1996, by and 
between WEST VALLEY BUSINESS TRUST ("Landlord") and INFONAUTICS CORPORATION, 
a Pennsylvania corporation ("Tenant").

     WHEREAS, by lease dated June, 1994 (the "Initial Lease"), Landlord 
leased to Tenant and Tenant leased from Landlord a portion of a building 
located at 900 West Valley Road, Wayne, Pennsylvania, consisting of 7,756 
square feet of space in building 900 as more particularly described in the 
Lease (the "Original Premises").

     WHEREAS, by that certain first amendment to lease dated January, 1995 
the ("First Amendment") Landlord leased to Tenant an additional (i) 1,522 
square feet of space in Building 1000 as more particularly described in the 
First Amendment ("First Expansion Space"), and (ii) 1,247 square feet of 
space in Building 1000 as more particularly described in the First Amendment 
("Second Expansion Space").

     WHEREAS, by that certain second amendment to lease dated June 30, 1995 
(the "Second Amendment") Landlord leased to Tenant an additional 5,462 square 
feet of space in Building 1100 more particularly described in the Second 
Amendment ("Third Expansion Space"), and Landlord and Tenant extended the 
Initial Term Expiration Date to July 31, 2000.

     WHEREAS, by that certain third amendment to lease dated as of November 
13, 1995, Landlord leased to Tenant Suite 1101 consisting of approximately 
1,509 square feet of space in Building 1100 as more particularly described in 
the Third Amendment ("Fourth Expansion Space").

     WHEREAS, by that certain fourth amendment to lease dated as of May 22, 
1996, Landlord and Tenant agreed to the terms of a utility access agreement.

     WHEREAS, pursuant to the terms of the Third Amendment, the Initial Lease 
was amended to redefine the term "Demised Premises" to include the Original 
Premises, the First Expansion Space, the Second Expansion Space, the Third 
Expansion Space and the Fourth Expansion Space thereby increasing the total 
square footage of the Demised Premises to 17,496 square feet and the Tenant's 
Proportionate Share to 10.83%.

     WHEREAS, Tenant desires to lease from Landlord and Landlord desires to 
lease to Tenant Suites 801, 802 and 804 consisting of approximately 3,544 
square feet of space in Building 800 as more particularly outlined on Exhibit 
"A" attached hereto ("Fifth Expansion Space") under the terms and conditions 
set forth herein.

     NOW THEREFORE, in consideration of the sum of $1.00, in hand well and 
truly paid, and other good and valuable consideration, the receipt of which 
is hereby



acknowledged, and in further consideration of the mutual premises and 
covenants herein contained, the parties, intending to be legally bound, agree:

     1.   The Initial Lease, as amended, is sometimes referred to herein as 
the "Lease." All other capitalized terms used in this Amendment shall have 
the same meanings as assigned to them in the WHEREAS clauses of this 
Amendment or the Lease, unless otherwise specifically noted. The provisions 
of the WHEREAS clauses are incorporated herein as if fully set forth.

     2.   Commencing on the Fifth Expansion Space Commencement Date, as 
defined in paragraph 3b below, the Lease is amended to redefine the term 
"Demised Premises" to include the Original Premises, the First Expansion 
Space, the Second Expansion Space, the Third Expansion Space, and the Fourth 
Expansion Space for all purposes, provided that the following provisions 
shall apply to the Fifth Expansion Space only notwithstanding any contrary 
provisions of the Lease: (i) the term of the lease of Fifth Expansion Space 
shall be five (5) years, terminating at 12:00 a.m. on the day before the 
fifth (5th) anniversary of the Fifth Expansion Space Commencement Date (and 
accordingly the lease of the Fifth Expansion Space shall continue after the 
July 31, 2000 Expiration Date of the lease of the First Expansion Space, the 
Second Expansion Space, the Third Expansion Space and the Fourth Expansion 
Space, determined without regard to the Extension Option with respect to such 
portions of the Demised Premises); (ii) the Extension Option provided in the 
Initial Lease shall not apply to the Fifth Expansion Space; (iii) the first 
and second termination options provided in the Initial Lease shall not apply 
to the Fifth Expansion Space, provided, however, that Tenant shall have the 
option to terminate the lease of the Fifth Expansion Space effective the day 
before the fourth (4th) anniversary of the Fifth Expansion Space Commencement 
Date, provided Tenant gives Landlord written notice of its election to 
terminate at least six (6) months prior to such termination date, and 
provided Tenant pays a termination fee to Landlord with said notice of 
$16,834; (iv) Tenant's Proportionate Share with respect to the Fifth 
Expansion Space only shall be 2.19% (3,544/161,519 sq. ft.); and (v) Base 
Rent for the Fifth Expansion Space shall be $55,818.00 per year, payable in 
advance in equal monthly installments of $4,651.50.

     3.   Landlord's Work.

          a.    Landlord hereby convenants and agrees with Tenant that 
Landlord shall: (1) cause an architect selected by Landlord to consult with 
Tenant concerning Tenant's construction improvement needs for occupancy of 
the Fifth Expansion Space and to prepare architectural, electrical and 
mechanical construction drawings, plans and specifications necessary to 
construct the improvements, subject to approval by Landlord and Tenant (as 
approved, the "Tenant Plans") to be made to the Fifth Expansion Space; (2) 
cause a contractor or contractors selected by Landlord to construct the 
improvements in the Fifth Expansion Space pursuant to the Tenant Plans with 
the objective of completing Landlord's Work not later than July 15, 1996 (the 
"Fifth Expansion Space Target Commencement Date"). Landlord's obligations 
under the preceding clauses (1) and (2) are sometimes herein 

                                       -2-







referred to together as "Landlord's Work". Tenant shall not request, nor 
shall Landlord have any obligation to approve, improvements that are not 
consistent with the quality of tenant improvements in the Building and class 
"A" general office space. Landlord's Work shall not include furniture and 
similar items not customarily included in "tenant improvements". Landlord's 
Work shall be performed at Landlord's cost and expense, not to exceed the 
amount of the $23,036 (the "Tenant Allowance"). In the event that (i) the 
costs of Landlord's Work exceed the Tenant Allowance, or (ii) Tenant requests 
changes in the Tenant Plans or Landlord's Work, which Landlord approves, and 
which increase the cost of Landlord's Work, and if such change or changes 
increase the cost of Landlord's Work to an amount in excess of the Tenant 
Allowance, the costs in excess of the Tenant Allowance shall be paid promptly 
by Tenant as additional rent hereunder. Tenant shall respond to any request 
from Landlord or Landlord's architect or contractor for approvals, 
authorizations to proceed or information in connection with Landlord's Work 
within two (2) business days of a request. 

          b.    The Fifth Expansion Space shall be deemed ready for occupancy 
and Landlord's Work shall be deemed to have been substantially completed on 
the date that: (i) Landlord's Work is complete except that minor or 
insubstantial details of construction, mechanical adjustment, or decoration 
remain to be performed, the non-completion of which do not materially 
interfere with Tenant's use of the Fifth Expansion Space; and (ii) all 
certificates of occupancy necessary for Tenant's occupancy of the Fifth 
Expansion Space have been issued. Landlord shall provide copies of such 
certificates of occupancy to Tenant upon request. Landlord shall provide Tenant
with notice of Landlord's substantial completion of Landlord's Work. Except as 
hereinafter provided, the Fifth Expansion Space Commencement Date of this 
Lease shall be the day that Landlord provides such notice. If Landlord's Work 
requires any specialized permits or approvals due to the nature of Tenant's 
use of specialized needs, Tenant shall be responsible for and shall obtain 
all such permits and approvals. At or prior to the Fifth Expansion Space 
Commencement Date, representatives of Landlord and Tenant shall inspect the 
Fifth Expansion Space and shall cooperate in producing and signing a punch 
list identifying Landlord's Work which has either not been completed or which 
has not been completed properly, and Landlord shall cause all items on such 
agreed punch list to be diligently completed or corrected, but such items 
shall not cause a postponement in the Fifth Expansion Space Commencement Date.

          c.    If the occurrence of the conditions listed in subsection b. 
above, and thereby the making of the Fifth Expansion Space ready for 
occupancy, shall be delayed due to:

          i.    Failure of Tenant to respond to any request from Landlord or 
Landlord's architect or contractor for approvals, authorizations to proceed 
or information in connection with the Tenant Plans and Landlord's Work within 
two (2) business days of a request; or

          ii.   Changes in Landlord's Work which are requested by Tenant and 
approved by Landlord; or 

                                       -3-




          iii.  Any other negligent or wrongful act or omission of Tenant or 
any of its employees, agents or contractors, then the Fifth Expansion Space 
shall be deemed ready for occupancy on the date when they would have been 
ready but for such delay (certified to Tenant in writing by Landlord's 
architect), and the Date of Substantial Completion shall be deemed to occur 
on such earlier date.

          d.    If and when Tenant shall take actual possession of the Fifth 
Expansion Space, it shall be conclusively presumed that the same was in 
satisfactory condition as of the date of such taking of possession, unless 
within twenty (20) days after such date Tenant shall give Landlord notice 
specifying the respects in which the Fifth Expansion Space was not in 
satisfactory condition.

          e.    If Landlord shall be unable to give possession of the Fifth 
Expansion Space on the Fifth Expansion Space Target Commencement Date by 
reason of the holding over or retention of possession of any tenant or 
occupant, or if repairs, improvements or decoration of the Fifth Expansion 
Space are not completed, or for any other reason, Landlord shall not be 
subject to any liability for the failure to give possession on said date. 
Instead, Landlord shall use reasonable efforts to provide possessions of the 
Fifth Expansion Space as soon as possible after the Fifth Expansion Space 
Target Commencement Date. No such failure to give possession on the Fifth 
Expansion Space Target Commencement Date shall in any other respect affect the
validity of this Lease or the obligation of Tenant hereunder.

          f.    By taking possession of the Fifth Expansion Space, Tenant 
shall be deemed to have accepted the Fifth Expansion Space as being in good 
sanitary order, condition and repair, except for the deficiencies identified 
in writing by Tenant as provided in subsection d. above. Tenant shall, at 
Tenant's sole cost and expense, keep the Fifth Expansion Space and every part 
thereof in good condition and repair, damage thereto from fire or other 
casualty and ordinary wear and tear, condemnation, and from the negligence or 
misconduct of Landlord, its agents, employees, invitees, contractors, 
subcontractors, and others for whom Landlord is legally responsible, alone 
excepted. Landlord shall have no obligation whatsoever to alter, remodel, 
improve, repair, decorate or paint the Fifth Expansion Space or any part 
thereof except as otherwise expressly provided herein or agreed upon in 
writing by Landlord, and the parties hereto affirm that Landlord has made no 
representations to Tenant respecting the condition of the Fifth Expansion 
Space or the Building except as specifically herein set forth in writing.

     4.   Tenant and Landlord agree that Tenant has no further expansion 
options under the Lease, and that Tenant has no extension option with 
respect to the Fifth Expansion Space.

     5.   ALL TIMES HEREIN AND IN THE LEASE ARE AND REMAIN OF THE ESSENCE.

                                       -4-




     6.   Except as modified herein, all terms and conditions of the Lease 
shall remain in full force and effect. In the event of any inconsistency 
between the terms of this Amendment and the terms of the Lease, the terms of 
this Amendment shall prevail. The Lease and this Amendment represent the 
entire agreement between the parties relating to the lease of the Premises 
and shall supersede any other agreements, whether written or oral. There are 
no understandings, representations or warranties of any kind, pertaining to 
the lease of the Premises which are not expressly set forth in this Amendment 
and the Lease. ALL OF THE CONFESSIONS OF JUDGMENTS FOR DAMAGES AND POSSESSION 
CONTAINED IN THE LEASE ARE HEREBY RATIFIED, CONFIRMED AND RESTATED BY TENANT 
AND ARE INCORPORATED HEREIN BY REFERENCE AS THOUGH SET FORTH IN THEIR 
ENTIRETY.

     IN WITNESS WHEREOF, the parties have hereunto set their hands and seals 
on the date first above mentioned.

                                       LANDLORD:

                                           WEST VALLEY BUSINESS TRUST

                                           By:  /s/ Robert W. Zwengler
                                              -----------------------
                                              an officer and not individually


                                       TENANT

                                           INFONAUTICS CORPORATION, a
                                           Pennsylvania corporation

                                           By:  /s/ Ronald A. Berg
                                              -----------------------
                                              Name:
                                              Title:

                                           Attest:  /s/ Donna Laquintano
                                                  -------------------
                                                   [Corporate Seal]


                                        -5-





Map of
West Valley
Business Center



Site Plan Exhibit "A"