SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                  SCHEDULE 13D
                                 (Rule 13d-101)

            INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
           TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO
                                 RULE 13d-2(a)

                               (Amendment No. 3)*

                                  Vysis, Inc.

                                (Name of Issuer)

                                  Common Stock

                         (Title of Class of Securities)

                                   928961101

                                 (CUSIP Number)

                               Daniel B. Pinkert
                                BP America Inc.
                            200 East Randolph Drive
                                 Mail Code 2106
                            Chicago, Illinois 60601
                                 (312) 856-3025

            (Name, Address and Telephone Number of Person Authorized
                     to Receive Notices and Communications)

                                October 24, 2001

            (Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box
[ ].

Note. This document is being  electronically filed with the Commission using the
EDGAR System. See Rule 13d-7 for other parties to whom copies are to be sent.
                         (Continued on following pages)
                              (Page 1 of 10 Pages)
                             ---------------------
    *The remainder of this cover page should be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which would
alter disclosures provide in a prior cover page.

     The information required on the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("ACT") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other provisions of the Act (however, see
the Notes).


1

 NAME OF REPORTING PERSONS
 I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

 BP p.l.c.; IRS No.: None

2

 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)	 (a) [x]
		 	 	 	 	 	 	 	 	 (b) [  ]

3

 SEC USE ONLY



4

 SOURCE OF FUNDS (SEE INSTRUCTIONS)

	OO

5

     CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
     OR 2(e) [  ]


6

 CITIZENSHIP OR PLACE OF ORGANIZATION

	England and Wales

NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH
REPORTING
PERSON
WITH

7

 SOLE VOTING POWER

	-0-


8

 SHARED VOTING POWER

	6,662,682


9

 SOLE DISPOSITIVE POWER

	-0-


10

 SHARED DISPOSITIVE POWER

	6,662,682

11

 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

		6,662,682

12

     CHECK IF THE  AGGREGATE  AMOUNT IN ROW (11)  EXCLUDES  CERTAIN  SHARES (SEE
     INSTRUCTIONS) [ ]

13

 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

65.1% (based on 10,241,438 shares outstanding as reported in the Form 10-Q
quarterly report for the quarterly period ended June 30, 2001)

14

 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	CO



1

 NAME OF REPORTING PERSONS
 I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

		BP America Inc.; IRS No.: 94-2257553

2

 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)	 (a) [x]
		 	 	 	 	 	 	 	 	 (b) [  ]

3

 SEC USE ONLY



4

 SOURCE OF FUNDS (SEE INSTRUCTIONS)

	OO

5

     CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
     OR 2(e) [ ]



6

 CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH
REPORTING
PERSON
WITH

7

 SOLE VOTING POWER

	-0-


8

 SHARED VOTING POWER

	6,662,682


9

 SOLE DISPOSITIVE POWER

	-0-


10

 SHARED DISPOSITIVE POWER

	6,662,682

11

 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

		6,662,682

12

     CHECK IF THE  AGGREGATE  AMOUNT IN ROW (11)  EXCLUDES  CERTAIN  SHARES (SEE
     INSTRUCTIONS) [ ]


13

 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

65.1% (based on 10,241,438 shares outstanding as reported in the Form 10-Q
quarterly report for the quarterly period ended June 30, 2001)

14

 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	CO







1

 NAME OF REPORTING PERSONS
 I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

		BP Corporation North America Inc.; IRS No.: 36-1812780

2

 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)	 (a) [x]
		 	 	 	 	 	 	 	 	 (b) [  ]

3

 SEC USE ONLY



4

 SOURCE OF FUNDS (SEE INSTRUCTIONS)

	OO

5

     CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
     OR 2(e) [ ]



6

 CITIZENSHIP OR PLACE OF ORGANIZATION

	Indiana

NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH
REPORTING
PERSON
WITH

7

 SOLE VOTING POWER

	-0-


8

 SHARED VOTING POWER

	6,662,682


9

 SOLE DISPOSITIVE POWER

	-0-


10

 SHARED DISPOSITIVE POWER

	6,662,682

11

 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	 	6,662,682

12

     CHECK IF THE  AGGREGATE  AMOUNT IN ROW (11)  EXCLUDES  CERTAIN  SHARES (SEE
INSTRUCTIONS) [ ]


13

 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

65.1% (based on 10,241,438 shares outstanding as reported in the Form 10-Q
quarterly report for the quarterly period ended June 30, 2001)

14

 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	CO







1

 NAME OF REPORTING PERSONS
 I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

		Amoco Technology Company; IRS No.: 36-3247360

2

 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)	 (a) [x]
		 	 	 	 	 	 	 	 	 (b) [  ]

3

 SEC USE ONLY



4

 SOURCE OF FUNDS (SEE INSTRUCTIONS)

	OO

5

     CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
     OR 2(e) [ ]



6

 CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware
NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH
REPORTING
PERSON
WITH

7

 SOLE VOTING POWER

	-0-


8

 SHARED VOTING POWER

	6,662,682


9

 SOLE DISPOSITIVE POWER

	-0-


10

 SHARED DISPOSITIVE POWER

	6,662,682

11

 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	 	6,662,682

12

     CHECK IF THE  AGGREGATE  AMOUNT IN ROW (11)  EXCLUDES  CERTAIN  SHARES (SEE
     INSTRUCTIONS) [ ]


13

 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

65.1% (based on 10,241,438 shares outstanding as reported in the Form 10-Q
quarterly report for the quarterly period ended June 30, 2001)

14

 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	CO


                        RELATING TO THE COMMON STOCK OF
                                  VYSIS, INC.

     This  Amendment  No. 3 amends the Schedule 13D filed  February 20, 1998, as
amended by the Amendment No. 1 filed  September 23, 1999 and the Amendment No. 2
filed July 11, 2001  (collectively,  the "Schedule  13D").  Unless  specifically
hereby amended,  the information in the Schedule 13D remains  unchanged.  Unless
otherwise defined herein, all defined terms used herein have the same meaning as
in the Schedule 13D.

Item 2.         Identity and Background

     Item 2 to the Schedule 13D is hereby supplemented and amended as follows:

     There have been  changes to the  executive  officers  and  directors  of BP
p.l.c. which are reflected on the attached Schedule I.

Item 4. Purpose of Transaction.

     Item 4 is hereby amended in its entirety to read as follows:

     The  6,662,682  shares of Common Stock of Vysis owned by ATC,  constituting
65.1% of the outstanding Vysis Common Stock, are held as an investment.  ATC and
BP have determined that ATC's investment in Vysis Common Stock is not strategic.
As  previously  reported  ATC  and BP  have  been  evaluating  alternatives  for
divestment  of all or a portion of ATC's  holdings  in Vysis  Common  Stock.
     On  October  24,  2001,  Abbott   Laboratories,   an  Illinois  corporation
("Abbott"), Rainbow Acquisition Corp., a Delaware corporation and a wholly owned
subsidiary of Abbott ("Rainbow") and Vysis entered into an Agreement and Plan of
Merger, dated as of October 24, 2001 (the "Merger  Agreement"),  which provides,
among other things,  for the  acquisition  of Vysis by Abbott by means of a cash
tender offer (the "Offer") for all of the issued and outstanding shares of Vysis
Common Stock and for the  subsequent  merger (the  "Merger") of Rainbow with and
into Vysis upon the terms and subject to the  conditions set forth in the Merger
Agreement.
     Concurrently  with  Abbott,  Rainbow  and Vysis  entering  into the  Merger
Agreement,  Abbott,  Rainbow,  BP and ATC entered into a Stockholder  Agreement,
dated as of October  24,  2001 (the  "Stockholder  Agreement").

     Pursuant to the Stockholder Agreement,  ATC has agreed, among other things,
that it

     will  tender  all of its  shares  of Vysis  Common  Stock  into the Offer
     promptly,  but  not  later  than  the  fifth  business  day  following  the
     commencement  of the  Offer,  and  that it  will  not  withdraw  any of its
     tendered  shares  of  Vysis  Common  Stock  so  long as the  Offer  remains
     outstanding;

     will not (a) dispose of or transfer  any  interest in or encumber  any of
     its shares of Vysis  Common  Stock,  (b) deposit its shares of Vysis Common
     Stock into a voting trust,  enter into any voting  arrangement or grant any
     proxy with  respect to its shares of Vysis  Common  Stock,  or (c) take any
     other action that would  interfere with the  performance of its obligations
     under the Stockholder Agreement;

     will vote or consent its shares of Vysis Common Stock (a) in favor of the
     Merger and  approval and  adoption of the Merger  Agreement  and any action
     required in furtherance  thereof,  (b) against any action or agreement that
     would  result in a breach of any  representation,  warranty  or covenant of
     Vysis in the Merger  Agreement,  and (c)  against  any action or  agreement
     which  would  delay,  postpone or attempt to  discourage  the Merger or the
     Offer or cause a condition to the closing of the Merger or the Offer to not
     be capable of being satisfied;

     irrevocably grants to, and appoints,  Abbott and any Abbott's nominee its
     proxy and  attorney-in-fact  (with full power of  substitution)  during the
     term of the Stockholder Agreement to vote its shares of Vysis Common Stock,
     or grant a consent or approval in respect of the shares, in connection with
     any meeting of the  stockholders  of Vysis:  (a) in favor of the Merger and
     approval and adoption of the Merger  Agreement  and any action  required in
     furtherance  thereof, (b) against any action or agreement that would result
     in a breach of any  representation,  warranty  or  covenant of Vysis in the
     Merger  Agreement,  and (c)  against  any action or  agreement  which would
     delay, postpone or attempt to discourage the Merger or the Offer or cause a
     condition  to the  closing  of the Merger or the Offer to not be capable of
     being satisfied; and

     irrevocably  waives any rights of appraisal or rights to dissent from the
     Merger.


The Stockholder Agreement also provides that

     from the date of the  Stockholder  Agreement  until  the  earlier  of the
     effective  time  of the  Merger  or  the  termination  of  the  Stockholder
     Agreement,  ATC will not (and ATC will not  permit  any of its  affiliates,
     officers,  directors  or  employees  or any  investment  banker,  financial
     advisor, attorney, accountant or other representative retained by it or any
     affiliate  (collectively  "Stockholder  Representatives")  to)  directly or
     indirectly:  (a) solicit, initiate, engage in discussions or negotiate with
     anyone or take any other  action  intended or designed  to  facilitate  any
     inquiry or effort of anyone (other than Abbott) relating to any Alternative
     Acquisition  (which is  defined in the  Merger  Agreement  as any direct or
     indirect  acquisition  of all or a  substantial  part of the  business  and
     properties of Vysis or any of Vysis'  subsidiaries  or any capital stock of
     Vysis or any of Vysis'  subsidiaries,  whether  by  merger,  tender  offer,
     exchange offer, sale of assets or similar  transactions  involving Vysis or
     any Vysis' subsidiary,  division or operating or principal business unit of
     Vysis);  (b)  provide  information  with  respect  to Vysis  or any  Vysis'
     Subsidiary to anyone, other than Abbott, relating to a possible Alternative
     Acquisition by anyone,  other than Abbott;  or (c) enter into any agreement
     with   respect   to   any   proposal   for  an   Alternative   Acquisition.
     Notwithstanding the foregoing, prior to the acceptance for payment of Vysis
     Common Stock  pursuant to the Offer,  ATC may advise the board of directors
     of  Vysis  of  receipt  by it (or any  Stockholder  Representative)  of any
     unsolicited  proposal  for  an  Alternative   Acquisition  or  any  inquiry
     indicating  that anyone is considering  making or wishes to make a proposal
     for  an  Alternative  Acquisition.   It  should  be  noted  that  the  term
     "Stockholder  Representative" does not include Vysis, any Vysis' Subsidiary
     or any  representative  of Vysis;

     ATC will promptly, and not later than within 2 business days, will advise
     Abbott of receipt by it (or any Stockholder Representative) of any proposal
     for an  Alternative  Acquisition or any inquiry  indicating  that anyone is
     considering  making  or  wishes  to  make a  proposal  for  an  Alternative
     Acquisition,  identifying such person, and the financial and other material
     terms and  conditions  of any proposal for an  Alternative  Acquisition  or
     potential proposal for an Alternative  Acquisition;  and

     ATC and BP cease and cause to be  terminated  all existing  discussion or
     negotiations  conducted  by them or at their  behest  with  respect  to any
     Alternative  Acquisition,  and that BP will promptly direct UBS Warburg LLC
     to  cease  and  cause  to  be  terminated   all  existing   discussions  or
     negotiations conducted by it with respect to any Alternative Acquisition on
     behalf of BP or its affiliates.

     Pursuant to the  Stockholder  Agreement,  Abbott and  Rainbow,  among other
things,  have agreed that without the prior written consent of ATC, Rainbow will
not (a) reduce the number of shares of Vysis Common Stock  subject to the Offer,
(b)  reduce  the  price it agreed to pay for the  shares of Vysis  Common  Stock
tendered pursuant to the Offer, (c) add to the conditions set forth in Exhibit A
of the Merger  Agreement or modify such  conditions in a manner  adverse to ATC,
(d) extend the Offer other than as provided in the  Stockholder  Agreement,  (e)
change the form of  consideration  payable  in the Offer,  or (f) make any other
change or  modification  in any of the terms of the Offer in any manner  that is
adverse to ATC.

     The Stockholder Agreement,  other than certain provisions contained herein,
will  terminate  upon the  earlier  of:  (a) the date  upon  which  the Offer is
terminated  without  the  purchase  of shares  of Vysis  Common  Stock;  (b) the
termination of the Merger Agreement; or (c) the effective time of the Merger.

     In addition to the above,  the  Stockholder  Agreement  also contains other
covenants,  terms and conditions,  as well as certain customary  representations
and  warranties  of the  parties.  The  above  description  of  the  Stockholder
Agreement  is  qualified  in  its  entirety  by  reference  to  the  Stockholder
Agreement,  a copy of which is filed as Exhibit 3 to this Amendment No. 3 and is
specifically incorporated herein by reference in response to this Item 4.

     Except as set forth  above,  ATC and BP do not have any plans or  proposals
that relate to or would result in any of the actions  specified in clauses (a) -
(j) of Item 4 in Schedule 13D.

Item 5.		Interest in Securities of the Issuer.

     Item 5 is amended to include the following:

     See "Item 4. Purpose of  Transaction"  for a description of the Stockholder
Agreement  which is qualified  in its  entirety by reference to the  Stockholder
Agreement and is specifically incorporated herein by reference in answer to this
Item 5.

Item 6. Contracts, Arrangements, Understandings or Relationships with
        Respect to the Securities of the Issuer.

     Item 6 is  amended  to  include  the  following:

     See "Item 4. Purpose of  Transaction"  for a description of the Stockholder
Agreement  which is qualified  in its  entirety by reference to the  Stockholder
Agreement and is specifically incorporated herein by reference in answer to this
Item 6.

Item 7.		Material to be Filed as Exhibits.

     Item 7 is amended to include the following:

     Exhibit  2 Joint  Filing  agreement,  dated  October  25,  2001.
     Exhibit 3 Stockholder Agreement, dated as of October 24, 2001, by and among
Abbott Laboratories,  Rainbow Acquisition Corp., Amoco Technology Company and BP
America Inc.


SIGNATURE
After reasonable inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this Statement is true, complete and correct.
Dated:	October 25, 2001
BP p.l.c.

By:  /s/ Lesley Stockwell
     ------------------------
Name: L. J. Stockwell
Title: Assistant Company Secretary

BP America Inc.

By:  /s/ D. B. Pinkert
     ------------------------
Name: D. B. Pinkert
Title: Corporate Secretary


BP Corporation North America Inc.

By:  /s/ D. B. Pinkert
     ------------------------
Name: D. B. Pinkert
Title: Corporate Secretary


Amoco Technology Company

By:  /s/ D. B. Pinkert
     ------------------------
Name: D. B. Pinkert
Title: Vice President


                                   SCHEDULE I

                      DIRECTORS AND EXECUTIVE OFFICERS OF
                                   BP p.l.c.


     The name, citizenship,  present principal occupation or employment, and the
name of any  corporation  or other  organization  in which  such  employment  is
conducted,  or each of the directors and executive  officers as October 24, 2001
of BP p.l.c.  ("BP") is set forth below.  Except as set forth below, each of the
directors  and  executive  officers  is a citizen  of the  United  Kingdom.  The
business  address of each director and officer is BP p.l.c.,  Britannic House, 1
Finsbury Circus,  London EC2M 7BA,  England.  Unless otherwise  indicated,  each
occupation set forth  opposite an executive  officer's name refers to employment
with BP.


NAME                            PRESENT PRINCIPAL OCCUPATION OR
                                EMPLOYMENT
--------------------------------------------------------------------------------

Directors                       (Executive Officer positions noted,
                                 where applicable)
--------------------------------------------------------------------------------
P. D. Sutherland                Non-executive Chairman, Chairman and Managing
(Ireland)                       Director of Goldman Sachs International

Sir Ian Prosser                 Non-executive Deputy Chairman, Chairman of Six
                                Continents PLC

The Lord Browne of Madingley    Executive Director and Group Chief Executive


Dr. J.G.S. Buchanan             Executive Director and Chief Financial Officer
(British and New Zealand)

R. F. Chase                     Executive Director and Deputy Group Chief
                                Executive

W. D. Ford                      Executive Director, Refining and Marketing

Dr. B.E. Grote                  Executive Director, Chemicals

R. L. Olver                     Executive Director, Exploration and Production

J. H. Bryan                     Non-executive Director, Chairman of Sara Lee
(United States)                 Corporation

E. B. Davis, Jr.                Non-executive Director, President and Chief
(United States)                 Executive Officer of Alliant Energy

C. F. Knight                    Non-executive Director, Chairman of Emerson
(United States)                 Electric

F. A. Maljers                   Non-executive Director, Chairman of the
(Netherlands)                   Supervisory Boards of the Amsterdam
                                Concertgebouw N.V., KLM Royal Dutch Airlines and
                                Rotterdam School of Management, Erasmus
                                University

Dr. W. E. Massey                Non-executive Director, President of Morehouse
(United States)                 College

H. M. P. Miles                  Non-executive Director, Chairman of Johnson
                                Matthey

Sir Robin Nicholson             Non-executive Director, retired Chairman of
                                Pilkington Optronics

M. H. Wilson                    Non-executive Director, President and Chief
(Canada)                        Executive Officer of RT Capital Management


Sir. R. Wilson                  Non-executive Director, Chairman
                                 of Rio Tinto plc


Executive Officers

J. C. Hanratty                  Company Secretary
(New Zealand)

G. R. Bradley                   Assistant Secretary

L. J. Stockwell                 Assistant Secretary





                               	Index To Exhibits

Exhibit No.     Exhibit

2               Joint Filing agreement, dated October 25, 2001

3               Stockholder  Agreement,  dated as of October 24, 2001,  by and
                among Abbott Laboratories,  Rainbow  Acquisition  Corp., Amoco
                Technology Company and BP America Inc.