SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D
          Under the Securities Exchange Act of 1934 (Amendment No. 4)*


                                  BioTime, Inc.
 ................................................................................
                                (Name of Issuer)

                           Common Shares, no par value
 ................................................................................
                         (Title of Class of Securities)

                                    09066L105
 ................................................................................
                                 (CUSIP Number)

                          Paul Segall and Judith Segall
          935 Pardee Street, Berkeley, California 94710; (510) 845-9535
 ................................................................................
 (Name, Address and Telephone Number of Person Authorized to Receive Notices 
                              and Communications)

                               September 16, 1997
 ................................................................................
              (Date of Event which Requires Filing this Statement)

If the filing person has previously  filed a statement on Schedule 13G to report
the  acquisition  which is the subject of this  Schedule 13D, and is filing this
schedule because of Rule 13d-1(b)(3) or (4), check the following box [ ].

Note: Six copies of this statement, including all exhibits, should be filed with
the  Commission.  See Rule  13d-1(a) for other  parties to whom copies are to be
sent.

*The  remainder of this cover page shall 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 provided in a prior cover page.






CUSIP No. 09066L105

         1)       Names of Reporting Persons S.S. or I.R.S. Identification Nos.
                  of Above Persons
                     Paul Segall

         2)       Check the Appropriate Box if a Member of a Group 
                  (See Instructions)
                                                                        (a) [ ]
                                                                        (b) [ ]
         3)       SEC Use Only

         4)       Source of Funds (See Instructions)
                           PF; OO

         5)       Check if Disclosure of Legal Proceedings is Required Pursuant
                  to Items 2(d) or 2(e)                                    [ ]

         6)       Citizenship or Place of Organization
                           U.S.A.

                  7)       Sole Voting Power
Number of                           172,459
Shares
Beneficially      8)       Shared Voting Power
Owned by                            0
Each
Reporting         9)       Sole Dispositive Power
Person With                         172,459

                  10)      Shared Dispositive Power
                                    0

         11)      Aggregate Amount Beneficially Owned by Each Reporting Person
                           236,638

         12)      Check if the Aggregate Amount in Row (11) Excludes Certain 
                  Shares (See Instructions)                                 [ ]

         13)      Percent of Class Represented by Amount in Row (11)
                           7.2%

         14)      Type of Reporting Person (See Instructions)
                           IN

                               Page 2 of 24 Pages





CUSIP No. 09066L105

         1)       Names of Reporting Persons S.S. or I.R.S. Identification Nos.
                  of Above Persons
                     Judith Segall

         2)       Check the Appropriate Box if a Member of a Group
                  (See Instructions)
                                                                        (a) [ ]
                                                                        (b) [ ]
         3)       SEC Use Only

         4)       Source of Funds (See Instructions)
                           PF; OO

         5)       Check if Disclosure of Legal Proceedings is Required Pursuant
                  to Items 2(d) or 2(e)                                     [ ]

         6)       Citizenship or Place of Organization
                           U.S.A.

                  7)       Sole Voting Power
Number of                           64,179
Shares
Beneficially      8)       Shared Voting Power
Owned by                            0
Each
Reporting         9)       Sole Dispositive Power
Person With                         64,179

                  10)      Shared Dispositive Power
                                    0

         11)      Aggregate Amount Beneficially Owned by Each Reporting Person
                           236,638

         12)      Check if the Aggregate Amount in Row (11) Excludes Certain 
                  Shares (See Instructions)                                 [ ]

         13)      Percent of Class Represented by Amount in Row (11)
                           7.2%

         14)      Type of Reporting Person (See Instructions)
                           IN

                               Page 3 of 24 Pages






Item 1.  Security and Issuer

         The class of equity securities to which this schedule relates is Common
Shares,  no par value (the  "Common  Shares"),  of BioTime,  Inc.,  a California
corporation (the "Company").  The Company has its principal executive offices at
935 Pardee Street, Berkeley, California 94710.

         This  schedule  is  being  filed  pursuant  to  Section  13(d)  of  the
Securities  Exchange Act of 1934, as amended (the "Exchange  Act") and the rules
and regulations promulgated thereunder.

Item 2.  Identity and Background

(a)      The names of the persons filing this schedule are Paul Segall and 
         Judith Segall.

(b)      The business address of Paul Segall and Judith Segall is 935 Pardee 
         Street, Berkeley, California 94710.

(c)      Paul Segall is currently the President and Chief Executive Officer of
         BioTime, Inc., 935 Pardee Street, Berkeley, California 94710.

         Judith Segall is currently the Secretary of BioTime, Inc.

(d)      Paul Segall and Judith Segall have not been  convicted  during the last
         five years in a criminal  proceeding,  excluding traffic  violations or
         similar misdemeanors.

(e)      Neither Paul Segall nor Judith  Segall has been a party during the last
         five years to any civil proceeding of a judicial or administrative body
         of competent jurisdiction, and neither of them has, as a result of such
         a  proceeding,  been  subject  to a  judgment,  decree  or final  order
         enjoining future violations of, or prohibiting or mandating  activities
         subject to, federal or state  securities  laws or finding any violation
         with respect to such laws.

(f)      Both Paul Segall and Judith Segall are citizens of the United States of
         America.

Item 3.  Source and Amount of Funds or Other Consideration

         The source of funds used by Paul  Segall and Judith  Segall to purchase
their Common Shares includes both personal funds and borrowed funds.

         Paul  Segall  has  executed  a  Customer   Agreement  with   Montgomery
Securities  and a related  Representation  Letter for the  purpose of  borrowing
$193,620 to exercise certain incentive stock options (through which he purchased
21,000  Common  Shares  at  a  price  of  $9.22  per  share)  and  approximately
$367,962.41  to refinance  certain  margin loans  obtained  from CS First Boston
during February 1997 in connection  with Mr.  Segall's  exercise of subscription
rights that were

                           Page 4 of 24 Pages 





distributed by the Company pro rata to its shareholders (the "Rights Offering").
Judith Segall has also executed a Customer Agreement with Montgomery  Securities
and a related  Representation Letter for the purpose of borrowing  approximately
$122,165 to refinance  certain margin loans obtained from CS First Boston during
February  1997 in  connection  with her exercise of  subscription  rights in the
Rights Offering.  Mr. and Mrs. Segall have pledged all of their Common Shares as
collateral  for such loans and have  agreed not tosell any Common  Shares of the
Company while their margin loans are secured by their Common  Shares.  A copy of
each of the aforesaid Customer Agreements and Representation Letters is filed as
an Exhibit to this Schedule 13D and each is incorporated herein by reference.


Item 4.  Purpose of Transaction

         These securities were purchased for investment.  Mr. and Ms. Segall may
acquire  additional  Common  Shares or sell all or some of their  Common  Shares
based upon market and economic circumstances.

         Mr. Segall is the President and Chief Executive Officer of the Company,
and Judith Segall is a Vice President and the Secretary of the Company. Both are
also directors of the Company. In their capacity as officers and directors, they
will participate in the management of the Company.

         Mr. and Ms.  Segall do not have any current  plans or  proposals  which
relate to or would result in (i) an extraordinary corporate transaction, such as
a merger,  reorganization or liquidation of the Company; (ii) a sale or transfer
of a material  amount of assets of the Company;  (iii) any change in the present
board  of  directors  or  management  of the  Company,  including  any  plans or
proposals  to change the  number or term of  directors  or to fill any  existing
vacancies on the board;  (iv) any material change in the present  capitalization
or  dividend  policy  of the  Company;  (v) any  other  material  change  in the
Company's  business or  corporate  structure;  (vi) any change in the  Company's
Articles  of  Incorporation  or Bylaws or other  action  which  may  impede  the
acquisition of control of the Company by any person;  (vii) causing any class of
the Company's  securities to be delisted from a national  securities exchange or
to cease to be authorized to be quoted in an inter-dealer  quotation system of a
registered national securities  association;  (viii) any of the Company's equity
securities becoming eligible for termination of registration pursuant to Section
12(g)(4)  of the  Exchange  Act;  or (ix)  any  action  similar  to any of those
enumerated above.

Item 5.  Interest in Securities of the Issuer

         (a) Paul Segall directly owns 172,459 Common Shares,  which  constitute
approximately  5.28% of the 3,266,193 Common Shares outstanding on September 17,
1997.  Judith  Segall  directly  owns 64,179  Common  Shares,  which  constitute
approximately  1.96% of the 3,266,193 Common Shares outstanding on September 17,
1997. The forgoing number of outstanding Common Shares is based upon information
provided by the Company.

                               Page 5 of 24 Pages





         (b) Mr. and Mrs.  Segall both have the sole power to vote and to direct
the vote,  and the sole power to dispose  and to direct  the  disposition,  with
respect to the shares held in their respective names.

         (c) On or about September 16, 1997, Paul Segall purchased 21,000 Common
Shares through the exercise of an incentive stock option at a price of $9.22 per
share.

         (d) Mr. and Ms.  Segall  both have the sole power to vote and to direct
the vote,  and the sole power to dispose  and to direct  the  disposition,  with
respect to the shares held in their  respective  names. No other person is known
to have the right to  receive or the power to direct  the  receipt of  dividends
from, or the proceeds from the sale of, their Common Shares.

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

         Paul Segall and Judith Segall are husband and wife and may consult with
each other or act jointly with respect to (a) voting Common Shares held in their
respective names, (b) acquiring  additional Common Shares,  and (c) disposing of
Common  Shares  held in their  respective  names.  To the extent that the Common
Shares constitute  community property under California law, each spouse may have
the right to dispose of one-half of the shares  constituting  community property
held by the other spouse.

Item 7.  Material to Be Filed as Exhibits

(a)      Customer Agreement between Paul Segall and Montgomery Securities

(b)      Representation Letter from Paul Segall to Montgomery Securities

(c)      Customer Agreement between Judith Segall and Montgomery Securities

(d)      Representation Letter from Judith Segall to Montgomery Securities


                           Page 6 of 24 Pages





Signature


         After  reasonable  inquiry and to the best of our  knowledge we certify
that the information set forth in the statement is true, complete and correct.

                                            /s/: Paul Segall
Dated:  September 24, 1997                 ____________________________________
                                                       Paul Segall

                                            /s/: Judith Segall
Dated:  September 24, 1997                 ____________________________________
                                                       Judith Segall

                           Page 7 of 24 Pages




                                                                    Exhibit (a)
MONTGOMERY SECURITIES


                               CUSTOMER AGREEMENT

  This  agreement  sets  forth the terms and  conditions  pursuant  to which we,
Montgomery  Securities,  and our  successors  and assigns,  will  maintain  your
account for purchases and sales of "securities and other property," which means,
but is not limited to securities,  financial instruments,  commodities and money
of every kind and nature and related  contracts  and  options.  This  definition
includes  securities or other property  currently or hereafter held,  carried or
maintained  by, or in the  possession  or control  of, us or any of our  related
entities for any purpose in and for any account now or hereafter  opened by you.
You  understand  that,  if your account is a cash  account,  the  provisions  of
paragraphs  18 & 19 are not  binding  upon you  unless  you enter  into a margin
transaction  and, if your account is a commodities  account,  the  provisions of
paragraph 14 shall not be applicable.

1.   APPLICABLE LAW AND  REGULATIONS.  All transactions in your account shall be
     subject  to all  applicable  laws  and the  rules  and  regulations  of all
     federal, state and self-regulatory agencies, including, but not limited to,
     the Board of Governors of the Federal Reserve System and the  constitution,
     rules,  customs  and usages of the  exchange  or market  (and its  clearing
     house) where the transactions are executed.

2.   SECURITY  INTEREST AND LIEN.  All securities or other property which we may
     at any time be carrying or maintaining  for you or which may at any time be
     in our possession or control for any purpose, including safekeeping,  shall
     be subject to a general lien for the  discharge of all of your  obligations
     to us,  irrespective  of whether or not we have made advances in connection
     with such securities or other property,  and  irrespective of the number of
     accounts you may have with us.

3.   DEPOSITS  ON  CASH  TRANSACTIONS.  If at  any  time  Montgomery  Securities
     considers it necessary for its protection, it may in its discretion require
     you to deposit cash or collateral in your account to assure due performance
     by you of your open contractual commitments.

4.   BREACH OR DEFAULT.  In the event of any breach by you of any agreement with
     us, or any  default  by you in any  obligation  to us, or should you die or
     file a petition in  bankruptcy or for the  appointment  of a receiver by or
     against you, or should we for any reason  whatsoever  deem it necessary for
     our protection, we are hereby authorized, at our discretion, to sell any or
     all of the  securities and other property in any of your accounts which may
     be in our possession or control, or which we may be carrying or maintaining
     for you (either  individually  or jointly  with  others),  or to buy-in any
     securities  or other  property  of which your  account or  accounts  may be
     short, or to cancel any other standing orders, to close out your account or
     accounts in whole or in part or in order to close out any  commitment  made
     on your  behalf.  Any  such  sale,  purchase  or  cancellation  may be made
     according  to our  judgment  and may be  made,  at our  discretion,  on the
     exchange or other market where such business is then usually transacted, or
     at public  auction or at private  sale,  without  advertising  the same and
     without notice to you or to your personal representative, and without prior
     tender,  demand  or call of any  kind  upon  you,  or  upon  your  personal
     representative  (each of  which is  expressly  waived  by you),  and we may
     purchase the whole or any part  thereof free from any right of  redemption,
     and you shall remain liable for any deficiency;  it being understood that a
     prior tender,  demand, call or notice of any kind shall not be considered a
     waiver of our right to sell or buy any  securities  and/or  other  property
     held  by us,  or  owed us by you,  at any  time as  hereinbefore  provided.
     Nothing  in this  agreement  shall be  construed  as  relieving  you of any
     obligations imposed by law.

5.   FINALITY OF REPORTS.  Reports of execution of orders and statements of your
     accounts shall become conclusive if not objected to in writing,  the former
     within five days, and the latter within ten days, after forwarding by us to
     you by mail or otherwise.


                               Page 8 of 24 Pages





6.   RECEIPT OF  TRUTH-IN-LENDING.  You hereby acknowledge receipt and review of
     Montgomery Securities' Truth-in-Lending disclosure statement contained here
     within.  You understand that interest will be charged on any debit balances
     in  accordance  with the  methods  described  in that  statement  or in any
     amendment  or  revision  thereto  which  may  be  provided  to  you.  It is
     understood and agreed that the interest  charge made to your account at the
     close of one charge period will be  compounded,  unless paid;  that is, the
     unpaid  interest  charge for previous  periods will be added to the opening
     balance for the next charge period,  thereby becoming part of the principal
     amount due and bearing like interest.

7.   TRANSFERS  BETWEEN  ACCOUNTS.  At any time and  from  time to time,  at our
     discretion,  we may without notice to you apply and/or  transfer any or all
     securities  and/or other property of yours  interchangeably  between any of
     your accounts.

8.   SELL ORDERS.  It is understood  and agreed that you will designate any sell
     order for a short  account  which you place  with us as a "short  sale" and
     hereby  authorize us to mark such order as being "short",  and when placing
     with us any order for a long account,  will designate it as such and hereby
     authorize  us to mark such order as being  "long." Any sell order which you
     shall  designate  as  being  for long  account  as  above  provided  is for
     securities  then  owned  by you  and,  if  such  securities  are  not  then
     deliverable  by us from any of your  accounts,  the  placing  of such order
     shall constitute a representation  by you that it is impracticable  for you
     to then  deliver  such  securities  to us but that you will deliver them as
     soon as it is  possible  for you to do so without  undue  inconvenience  or
     expense.

9.   AGE, BENEFICIAL INTEREST. If you are an individual,  you represent that you
     are of full legal age,  and, in any event not less than  eighteen  years of
     age. You further  represent  that no one except you has an interest in your
     account with us.

10.  OPERATIONAL MATTERS.  Montgomery Securities primarily uses banks located in
     California and New York to issue checks.  Also, when we hold securities for
     your  account,  dividends and interest are credited on or about the payable
     date as received.  Most of our customers prefer to have these funds held in
     their  accounts,  and this will be the procedure  which we will follow with
     your account  unless you advise us of an  alternative  procedure  which you
     would  prefer.  For example,  we could arrange for checks to be sent to you
     monthly.  If you require special  arrangements,  please bring the matter to
     our attention. Montgomery Securities' policy is not to receive remuneration
     for directing  orders to particular  brokers/dealers  or market centers for
     execution.   Notwithstanding  this  policy,  should  Montgomery  Securities
     receive such remuneration on any transaction,  appropriate  disclosure will
     be made.

11.  CREDIT REPORT.  Montgomery  Securities may, in its  discretion,  request an
     investigative  consumer report on you as a credit  reference,  which report
     may include  information  with respect to  character,  general  reputation,
     personal  characteristics  and mode of living.  In accordance with the Fair
     Credit Reporting Act, a copy of any such report, if obtained,  will be made
     available to you upon written request.

12.  CLEARANCE  ACCOUNTS.  If  Montgomery  Securities  carries  your account as
     clearing  broker by arrangement  with another broker through whose courtesy
     your  account  has  been  introduced,  then  unless  Montgomery  Securities
     receives from you a written notice to the contrary,  Montgomery  Securities
     shall accept from such other broker,  without any inquiry or  investigation
     by us,  (i)  orders  for the  purchase  and sale of  securities  and  other
     property on margin or otherwise, and (ii) any other instructions concerning
     said  account.   You  understand   Montgomery   Securities  shall  have  no
     responsibility  or liability to you for any acts or omissions of such other
     broker, its officers, employees or agents.

13.  WAIVER, ASSIGNMENT AND NOTICES. No term or provision of this Agreement
     may be waived or modified unless in writing and signed by the party against
     whom such  waiver or  modification  is  sought to be  enforced.  Montgomery
     Securities'  failure to insist at any time upon strict compliance with this
     Agreement  or with any of the terms  hereunder or any  continued  course of
     such conduct on its part shall in no event  constitute  or be  considered a
     waiver by Montgomery  Securities of any of its rights or  privileges.  This
     Agreement  contains  the entire  understanding  between you and  Montgomery
     Securities concerning the subject matter of this

                               Page 9 of 24 Pages





     Agreement.  You may not assign your rights or obligations hereunder without
     first obtaining the prior written consent of Montgomery Securities.  Notice
     or other communications, including margin calls, delivered or mailed to the
     address given below shall, until Montgomery  Securities has received notice
     in  writing  of a  different  address,  be deemed  to have been  personally
     delivered to you.

14.  ARBITRATION.

      o ARBITRATION IS FINAL AND BINDING ON THE PARTIES.

      o THE PARTIES ARE WAIVING THEIR RIGHT TO SEEK REMEDIES IN COURT, INCLUDING
      THE RIGHT TO JURY TRIAL.

      o  PRE-ARBITRATION  DISCOVERY IS GENERALLY MORE LIMITED THAN AND DIFFERENT
      FROM COURT PROCEEDINGS.

      o THE  ARBITRATORS'  AWARD IS NOT REQUIRED TO INCLUDE FACTUAL  FINDINGS OR
      LEGAL REASONING AND ANY PARTY'S RIGHT TO APPEAL OR TO SEEK MODIFICATION OF
      RULINGS BY THE ARBITRATORS IS STRICTLY LIMITED.

      o  THE  PANEL  OF  ARBITRATORS  WILL  TYPICALLY   INCLUDE  A  MINORITY  OF
      ARBITRATORS WHO WERE OR ARE AFFILIATED WITH THE SECURITIES INDUSTRY.

      YOU  AGREE,  AND BY  CARRYING  AN  ACCOUNT  FOR YOU,  WE  AGREE,  THAT ALL
      CONTROVERSIES WHICH MAY ARISE BETWEEN US CONCERNING ANY TRANSACTION OR THE
      CONSTRUCTION, PERFORMANCE OR BREACH OF THIS OR ANY OTHER AGREEMENT BETWEEN
      US,  WHETHER  ENTERED INTO PRIOR,  ON, OR  SUBSEQUENT  TO THE DATE HEREOF,
      SHALL BE DETERMINED BY ARBITRATION.  ANY ARBITRATION  UNDER THIS AGREEMENT
      SHALL BE CONDUCTED ONLY IN THE FORUMS PROVIDED BY THE NATIONAL ASSOCIATION
      OF  SECURITIES  DEALERS,  INC. OR THE BOARD OF  GOVERNORS  OF THE NEW YORK
      STOCK  EXCHANGE,  INC., AS YOU MAY ELECT. IF YOU DO NOT MAKE SUCH ELECTION
      BY REGISTERED  MAIL  ADDRESSED TO MONTGOMERY  SECURITIES,  600  MONTGOMERY
      STREET, SAN FRANCISCO, CA 94111, ATTENTION: LEGAL DEPARTMENT, AND RECEIVED
      WITHIN  FIVE DAYS  AFTER  DEMAND BY US THAT YOU MAKE SUCH  ELECTION,  THEN
      MONTGOMERY   SECURITIES  MAY  MAKE  SUCH   ELECTION.   THE  AWARD  OF  THE
      ARBITRATORS, OR OF THE MAJORITY OF THEM, SHALL BE FINAL, AND JUDGMENT UPON
      ANY AWARD RENDERED BY THE  ARBITRATORS  MAY BE ENTERED IN ANY COURT HAVlNG
      JURISDICTION THEREOF.

      No person shall bring a putative or certified class action to arbitration,
      nor seek to enforce  any  pre-dispute  arbitration  agreement  against any
      person  who has  initiated  in court a putative  class  action or who is a
      member of a putative class who has not opted out of the class with respect
      to any claims  encompassed  by the putative  class action  until:  (i) the
      class certification is denied; (ii) the class is decertified; or (iii) the
      customer  is excluded  from the class by the court.  Such  forbearance  to
      enforce an  agreement to  arbitrate  shall not  constitute a waiver of any
      rights under this agreement except to the extent stated herein.

15.   NEW  YORK LAW TO  GOVERN.  This  Agreement  and its  enforcement  shall be
      governed  by the  laws of the  State of New York  (without  regard  to any
      principles of conflicts of law) and its  provisions  shall be  continuous;
      shall cover  individually and collectively all accounts which you may open
      or  reopen  with  us,  and  shall  inure  to the  benefit  of our  present
      organization,  and any successor organization,  irrespective of any change
      or changes at any time in the personnel thereof, for any cause whatsoever,
      and of the assigns of our present organization

                               Page 10 of 24 Pages





      or any successor organization,  and shall be binding upon you, and/or your
      estate, executors, administrators, heirs and assigns.

16.   PARTIAL  UNENFORCEABILITY.  If any  provision  herein is or should  become
      inconsistent  with any present or future law,  rule or  regulation  of any
      sovereign  government or a regulatory  body having  jurisdiction  over the
      subject  matter  of  this  Agreement  or is held  to be  invalid,  void or
      unenforceable by reason of any law, rule, administrative order or judicial
      decision,  such  provision  shall be deemed to be rescinded or modified in
      accordance with any such law, rule, regulation,  order or decision. In all
      other respects, this Agreement shall continue and remain in full force and
      effect.

17.   LIMIT ORDERS.  Montgomery  Securities reserves the right to not accept
      from customers  limit orders in NASDAQ or  over-the-counter  securities in
      which it acts as a market maker.


18.   MARGIN IN MARGIN ACCOUNTS (NOT APPLICABLE TO CASH ACCOUNTS).You hereby
      agree to  maintain  such  margin  in your  margin  account  as  Montgomery
      Securities may in its discretion require and you agree to pay forthwith on
      demand  any  debit  balance  owing  with  respect  to any of  your  margin
      accounts,  and if not paid this  shall be a breach of this  Agreement  and
      Montgomery  Securities may take such action as it considers  necessary for
      its protection in accordance  with this  Agreement.  You understand  that,
      even if Montgomery Securities has a policy of giving customers notice of a
      margin  deficiency,  Montgomery  Securities  is not  obligated  to request
      additional  margin  from  you,  and  there  may  be  circumstances   where
      Montgomery  Securities will liquidate  securities and/or other property in
      your account  without notice to you. You will be charged  interest on your
      debit balance which if not paid at the close of an interest period will be
      added to the opening balance for the next interest period.  Please consult
      the attached disclosure statement for an outline of Montgomery Securities'
      interest policies.

19.   CUSTOMER'S CONSENT TO LOAN OR PLEDGE OF SECURITIES AND OTHER PROPERTY (NOT
      APPLICABLE TO CASH ACCOUNTS).  You hereby authorize Montgomery  Securities
      to lend either to itself or to others any  securities  and other  property
      held by Montgomery Securities in your margin account and to carry all such
      property in its general loans and such property may be pledged, repledged,
      hypothecated or  rehypothecated,  without notice to you, either separately
      or in common with other such  property  for any amounts due to  Montgomery
      Securities  thereon or for a greater sum, and Montgomery  Securities shall
      have no  obligation  to retain a like  amount of similar  property  in its
      possession and control.

      BY SIGNING THIS  AGREEMENT  YOU  ACKNOWLEDGE  THAT THE  SECURITIES IN YOUR
MARGIN  ACCOUNT MAY BE LOANED TO  MONTGOMERY  SECURITIES OR LOANED OUT TO OTHERS
AND THAT YOU HAVE RECEIVED AND REVIEWED A COPY OF THIS AGREEMENT.

      THIS AGREEMENT CONTAINS A PRE-DISPUTE ARBITRATION CLAUSE AT PAGES 2-3 AT
PARAGRAPH 14.

      IF JOINT  ACCOUNT  BOTH PARTIES  MUST SIGN.  Persons  signing on behalf of
others please indicate title or capacity in which you have signed.

              Paul Segall
- ------------------------------------------------
            (Typed or Printed Name)

             /s/: Paul Segall
- ------------------------------------------------
                  (Signature)


- ------------------------------------------------
                  (Signature)

                               Page 11 of 24 Pages






     c/o BioTime, Inc., 935 Pardee Street
- ------------------------------------------------
               (Mailing Address)

     Berkeley,           CA             94710
- ------------------------------------------------
        (City)         (State)           (Zip)

                    9/12/97
- ------------------------------------------------
                       (Date)


Acct.          XXX-XXXXX
No.:____________________________________________


                               Page 12 of 24 Pages






                         ADDENDUM TO CUSTOMER AGREEMENT



      Hypothecation of Customer Securities. Notwithstanding any provision of the
Customer Agreement to the contrary, Montgomery Securities shall not lend, pledge
or hypothecate any securities owned by Customer  (whether or not such securities
are held by Montgomery  Securities as Collateral for Customer's  Obligations) to
facilitate any short sale or otherwise;  provided, that this provision shall not
prevent the sale of Collateral pursuant to Section 4.

      Death or  Incompetency  of Customer.  Montgomery  Securities will not take
action  pursuant  to Section 4 solely  because of  Customer's  death or adjudged
incompetency if either (a) within 30 days after the date of Customer's  death or
declaration  of  incompetency  and  an  administrator,   executor,  conservator,
guardian or other  personal  representative  has  authority  to make  investment
decisions with respect to Customer's  account, or (b) with respect to Customer's
incompetency,   Customer  has  executed  a  power  of  attorney  designating  an
attorney-in-fact  who shall  have the power to make  investment  decisions  with
respect to Customer's account.



/s/: Paul Segall                             /s/: Wilson T. Hileman
- ----------------------------             ------------------------------
Customer Signature                           For Montgomery Securities

Paul Segall                               Wilson T. Hileman - Managing Director
- ----------------------------             --------------------------------------
Print Name                                    Print Name and Title

             XXX-XXXXX-XXX
Account No._________________




                               Page 13 of 24 Pages




                                                                     Exhibit (b)
                Representation letter FOR AFFILIATES of a Company
                  whose Stock is used as collateral for Margin




      Montgomery Securities
      600 Montgomery Street
      San Francisco, CA 94111.

         Attn:    Margin Department

         Gentlemen:

                  Reference  is made to the Customer  Agreement I executed  with
         you, pursuant to which you opened and maintain account number XXX-XXXXX
         for me, and which  agreement  governs the extension and  maintenance of
         margin credit with respect to such account.

                  I am an  affiliate  (as  defined in Rule 144 (a) (1) under the
         Securities Act of 1933 (the "Act") of Biotime, Inc. (the "Company").  I
         wish to obtain  margin  credit on not more  than  90,000  shares of the
         common stock (the  "Securities")  of the Company.  I understand that in
         order for you to extend margin credit to me which is  collateralized by
         the  Securities,  you must be able to sell the  Securities  pursuant to
         Rule  144  of  the  Act  ("Rule  14+"),  which  requires  that  certain
         conditions  must be met.  Accordingly,  I hereby  represent  to you and
         covenant with you as follows:

         1.   I acquired  and fully paid for the  Securities  on January  18,
              1991.  The  Securities  are  "restricted  securities"  within  the
              meaning of Rule 144, and bear a legend describing  restrictions on
              the transfer of the Securities.

         2.   In the preceding three months, I, together with all persons who
              are  considered  the same "person" as me under Rule  l44(a)(2) and
              all persons whose sales must be  aggregated  with mine pursuant to
              Rule 144(e)(3), have sold 0 shares of common stock of the Company.
              - --------------------------------------

         3.   The Securities, together with all shares of capital stock of the
              Company held by persons whose sales would be aggregated with sales
              by me  pursuant  to Rule 1  4+(e)(3),  constitute  less  -than the
              greater  of (i) 1% of the  shares of common  stock of the  Company
              currently  outstanding or (ii) the average weekly  reported volume
              of  trading  in the Common  Stock of the  Company on all  national
              securities  exchanges,  through the Nasdaq Stock Market, Inc., and
              /or through the consolidated transaction reporting system. I agree
              that for the  duration of the period for which my margin loan from
              Montgomery  is  collateralized,  in  whole  or  in  part,  by  the
              Securities, I will not transfer any

                               Page 14 of 24 Pages






              shares of capital  stock of the Company to any person  whose sales
              would be aggregated with sales by me pursuant to Rule l44(e)(3).

              In addition,  I have held 26,690  securities  of the Company for a
              period of at least two years from the date hereof (the "Additional
              Securities").   I  also  p1edge  the   Additional   Securities  as
              collateral  in order  for you to  extend  margin  credit  to me. I
              understand  that you may sell the  Additional  Securities  without
              regard to the volume  'imitation  under Rule 144 if you  institute
              foreclosure proceedings against my account.

         4.   I agree that for the duration of the period for which my margin
              loan from Montgomery Securities is collateralized,  in whole or in
              part,  by the  Securities,  I will not sell,  and I will cause all
              persons  who are  considered  the same  "person"  as me under Rule
              l44(a)(2) not to sell, any shares of common stock of the Company.

         5.   I will not use any margin credit to purchase  securities of any
              other company of which lam an affiliate (as defined in Rule 144(a)
              (1)).

         6.   I have no outstanding borrowing  collateralized by any shares of
              capital  stock of the Company and I will not incur such  borrowing
              from any other  person for the duration of the period for which my
              margin loan from Montgomery Securities is collateralized, in whole
              or in part, by the Securities.

         7.   I have  delivered  to you an  executed  Form  144,  a  Seller's
              Representation  Letter under Rule 144 and such other  documents as
              you have requested to enable you to sell the Securities under Rule
              144 at any time you may consider it necessary for your protection.
              The information  contained in these documents is true and correct.
              You may rely on the continued  accuracy and  completeness  of such
              information  unless and until I have informed you m writing of any
              changes to such  information  and have provided you with corrected
              versions  of such  documents I will not take any action or omit to
              take any action that would prevent you from selling the Securities
              at any time pursuant to Rule 144.

         8.   I will notify you  immediately  of any  occurrence  which would
              render any of the foregoing representations inaccurate.

         9.   I am  familiar  with  the  provisions  of  Section  16 of  the
              Securities   Exchange  Act  of  1934  and  the  rules  promulgated
              thereunder.  I understand the possible  consequences  to me if you
              sell the  Securities  at a time when such sale  would  deem 'me to
              have received  "short-swing"  profits,  which  consequences  could
              include the payment to the Company by me of all such profits.

                               Page 15 of 24 Pages





The Company, its transfer agent and their agents and representatives may rely on
this letter. I will indemnify you and hold you harmless from and against any and
all loss, damage, claim,  liability and expense arising out of or resulting from
the breach of any representation or covenant herein.

Very truly yours,
Paul Segall

                               Page 16 of 24 Pages



                                                                     Exhibit (c)
MONTGOMERY SECURITIES


                               CUSTOMER AGREEMENT

  This  agreement  sets  forth the terms and  conditions  pursuant  to which we,
Montgomery  Securities,  and our  successors  and assigns,  will  maintain  your
account for purchases and sales of "securities and other property," which means,
but is not limited to securities,  financial instruments,  commodities and money
of every kind and nature and related  contracts  and  options.  This  definition
includes  securities or other property  currently or hereafter held,  carried or
maintained  by, or in the  possession  or control  of, us or any of our  related
entities for any purpose in and for any account now or hereafter  opened by you.
You  understand  that,  if your account is a cash  account,  the  provisions  of
paragraphs  18 & 19 are not  binding  upon you  unless  you enter  into a margin
transaction  and, if your account is a commodities  account,  the  provisions of
paragraph 14 shall not be applicable.

1.    APPLICABLE LAW AND REGULATIONS.  All transactions in your account shall be
      subject  to all  applicable  laws and the  rules  and  regulations  of all
      federal, state and self-regulatory  agencies,  including,  but not limited
      to,  the  Board  of  Governors  of the  Federal  Reserve  System  and  the
      constitution, rules, customs and usages of the exchange or market (and its
      clearing house) where the transactions are executed.

2.    SECURITY  INTEREST AND LIEN. All securities or other property which we may
      at any time be carrying or maintaining for you or which may at any time be
      in our possession or control for any purpose, including safekeeping, shall
      be subject to a general lien for the discharge of all of your  obligations
      to us,  irrespective of whether or not we have made advances in connection
      with such securities or other property,  and irrespective of the number of
      accounts you may have with us.

3.    DEPOSITS ON CASH  TRANSACTIONS.  If at any time  Montgomery  Securities
      considers  it  necessary  for  its  protection,  it may in its  discretion
      require you to deposit  cash or  collateral  in your account to assure due
      performance by you of your open contractual commitments.

4.    BREACH OR DEFAULT. In the event of any breach by you of any agreement with
      us, or any  default by you in any  obligation  to us, or should you die or
      file a petition in bankruptcy or for the  appointment  of a receiver by or
      against you, or should we for any reason  whatsoever deem it necessary for
      our protection,  we are hereby authorized,  at our discretion, to sell any
      or all of the  securities and other property in any of your accounts which
      may be in our  possession  or  control,  or  which we may be  carrying  or
      maintaining for you (either  individually  or jointly with others),  or to
      buy-in any  securities or other property of which your account or accounts
      may be short,  or to cancel any other standing  orders,  to close out your
      account  or  accounts  in whole  or in part or in  order to close  out any
      commitment  made on your behalf.  Any such sale,  purchase or cancellation
      may be made according to our judgment and may be made, at our  discretion,
      on the  exchange  or other  market  where such  business  is then  usually
      transacted,  or at public auction or at private sale, without  advertising
      the same and without notice to you or to your personal representative, and
      without  prior  tender,  demand or call of any kind upon you, or upon your
      personal representative (each of which is expressly waived by you), and we
      may  purchase  the  whole  or any part  thereof  free  from  any  right of
      redemption,  and you shall  remain  liable  for any  deficiency;  it being
      understood that a prior tender,  demand,  call or notice of any kind shall
      not be  considered  a waiver  of our  right to sell or buy any  securities
      and/or  other  property  held by us,  or owed  us by you,  at any  time as
      hereinbefore  provided.  Nothing in this  agreement  shall be construed as
      relieving you of any obligations imposed by law.

5.    FINALITY OF REPORTS. Reports of execution of orders and statements of your
      accounts shall become conclusive if not objected to in writing, the former
      within five days, and the latter within ten days,  after  forwarding by us
      to you by mail or otherwise.


                               Page 17 of 24 Pages





6.    RECEIPT OF TRUTH-IN-LENDING.  You hereby acknowledge receipt and review of
      Montgomery  Securities'  Truth-in-Lending  disclosure  statement contained
      here within.  You  understand  that  interest will be charged on any debit
      balances in accordance with the methods  described in that statement or in
      any  amendment  or  revision  thereto  which may be provided to you. It is
      understood and agreed that the interest charge made to your account at the
      close of one charge period will be compounded,  unless paid;  that is, the
      unpaid interest  charge for previous  periods will be added to the opening
      balance for the next charge period, thereby becoming part of the principal
      amount due and bearing like interest.

7.    TRANSFERS BETWEEN ACCOUNTS. At any time and from time to time, at our 
      discretion,  we may without notice to you apply and/or transfer any or all
      securities and/or other property of yours  interchangeably  between any of
      your accounts.

8.    SELL ORDERS. It is understood and agreed that you will designate any sell
      order for a short  account  which you place with us as a "short  sale" and
      hereby authorize us to mark such order as being "short",  and when placing
      with us any order for a long account, will designate it as such and hereby
      authorize us to mark such order as being  "long." Any sell order which you
      shall  designate  as being  for long  account  as  above  provided  is for
      securities  then  owned  by you  and,  if such  securities  are  not  then
      deliverable  by us from any of your  accounts,  the  placing of such order
      shall constitute a representation  by you that it is impracticable for you
      to then  deliver such  securities  to us but that you will deliver them as
      soon as it is possible for you to do so without undue
      inconvenience or expense.

9.    AGE, BENEFICIAL INTEREST. If you are an individual, you represent that you
      are of full legal age, and, in any event not less than  eighteen  years of
      age. You further  represent that no one except you has an interest in your
      account with us.

10.   OPERATIONAL MATTERS. Montgomery Securities primarily uses banks located in
      California and New York to issue checks.Also,  when we hold securities for
      your account,  dividends and interest are credited on or about the payable
      date as received. Most of our customers prefer to have these funds held in
      their  accounts,  and this will be the procedure which we will follow with
      your account  unless you advise us of an alternative  procedure  which you
      would prefer.  For example,  we could arrange for checks to be sent to you
      monthly. If you require special  arrangements,  please bring the matter to
      our   attention.   Montgomery   Securities'   policy  is  not  to  receive
      remuneration for directing orders to particular  brokers/dealers or market
      centers for  execution.  Notwithstanding  this policy,  should  Montgomery
      Securities  receive  such  remuneration  on any  transaction,  appropriate
      disclosure will be made.

11.   CREDIT REPORT.  Montgomery  Securities may, in its discretion,  request an
      investigative  consumer report on you as a credit reference,  which report
      may include  information  with respect to character,  general  reputation,
      personal  characteristics  and mode of living. In accordance with the Fair
      Credit Reporting Act, a copy of any such report, if obtained, will be made
      available to you upon written request.

12.   CLEARANCE  ACCOUNTS.  If  Montgomery  Securities  carries  your account as
      clearing broker by arrangement  with another broker through whose courtesy
      your  account  has been  introduced,  then  unless  Montgomery  Securities
      receives from you a written notice to the contrary,  Montgomery Securities
      shall accept from such other broker,  without any inquiry or investigation
      by us,  (i)  orders  for the  purchase  and sale of  securities  and other
      property  on  margin  or  otherwise,   and  (ii)  any  other  instructions
      concerning said account. You understand  Montgomery  Securities shall have
      no  responsibility  or  liability to you for any acts or omissions of such
      other broker, its officers, employees or agents.

13.   WAIVER, ASSIGNMENT AND NOTICES. No term or provision of this Agreement may
      be waived or modified  unless in writing  and signed by the party  against
      whom such  waiver or  modification  is sought to be  enforced.  Montgomery
      Securities' failure to insist at any time upon strict compliance with this
      Agreement or with any of the terms  hereunder or any  continued  course of
      such conduct on its part shall in no event  constitute  or be considered a
      waiver by Montgomery  Securities of any of its rights or privileges.  This
      Agreement  contains the entire  understanding  between you and  Montgomery
      Securities concerning the subject matter of this

                           Page 18 of 24 Pages





      Agreement. You may not assign your rights or obligations hereunder without
      first obtaining the prior written consent of Montgomery Securities. Notice
      or other  communications,  including margin calls,  delivered or mailed to
      the address given below shall,  until  Montgomery  Securities has received
      notice  in  writing  of a  different  address,  be  deemed  to  have  been
      personally delivered to you.

14.  ARBITRATION.

      o     ARBITRATION IS FINAL AND BINDING ON THE PARTIES.

      o     THE  PARTIES  ARE  WAIVING  THEIR  RIGHT TO SEEK  REMEDIES IN COURT,
            INCLUDING THE RIGHT TO JURY TRIAL.

      o     PRE-ARBITRATION   DISCOVERY  IS  GENERALLY  MORE  LIMITED  THAN  AND
            DIFFERENT FROM COURT PROCEEDINGS.

      o     THE  ARBITRATORS'  AWARD IS NOT REQUIRED TO INCLUDE FACTUAL FINDINGS
            OR  LEGAL  REASONING  AND ANY  PARTY'S  RIGHT TO  APPEAL  OR TO SEEK
            MODIFICATION OF RULINGS BY THE ARBITRATORS IS STRICTLY LIMITED.

o      THE PANEL OF ARBITRATORS WILL TYPICALLY INCLUDE A MINORITY OF ARBITRATORS
      WHO WERE OR ARE AFFILIATED WITH THE SECURITIES INDUSTRY.

      YOU  AGREE,  AND BY  CARRYING  AN  ACCOUNT  FOR YOU,  WE  AGREE,  THAT ALL
      CONTROVERSIES WHICH MAY ARISE BETWEEN US CONCERNING ANY TRANSACTION OR THE
      CONSTRUCTION, PERFORMANCE OR BREACH OF THIS OR ANY OTHER AGREEMENT BETWEEN
      US,  WHETHER  ENTERED INTO PRIOR,  ON, OR  SUBSEQUENT  TO THE DATE HEREOF,
      SHALL BE DETERMINED BY ARBITRATION.  ANY ARBITRATION  UNDER THIS AGREEMENT
      SHALL BE CONDUCTED ONLY IN THE FORUMS PROVIDED BY THE NATIONAL ASSOCIATION
      OF  SECURITIES  DEALERS,  INC. OR THE BOARD OF  GOVERNORS  OF THE NEW YORK
      STOCK  EXCHANGE,  INC., AS YOU MAY ELECT. IF YOU DO NOT MAKE SUCH ELECTION
      BY REGISTERED  MAIL  ADDRESSED TO MONTGOMERY  SECURITIES,  600  MONTGOMERY
      STREET, SAN FRANCISCO, CA 94111, ATTENTION: LEGAL DEPARTMENT, AND RECEIVED
      WITHIN  FIVE DAYS  AFTER  DEMAND BY US THAT YOU MAKE SUCH  ELECTION,  THEN
      MONTGOMERY   SECURITIES  MAY  MAKE  SUCH   ELECTION.   THE  AWARD  OF  THE
      ARBITRATORS, OR OF THE MAJORITY OF THEM, SHALL BE FINAL, AND JUDGMENT UPON
      ANY AWARD RENDERED BY THE  ARBITRATORS  MAY BE ENTERED IN ANY COURT HAVlNG
      JURISDICTION THEREOF.

      No person shall bring a putative or certified class action to arbitration,
      nor seek to enforce  any  pre-dispute  arbitration  agreement  against any
      person  who has  initiated  in court a putative  class  action or who is a
      member of a putative class who has not opted out of the class with respect
      to any claims  encompassed  by the putative  class action  until:  (i) the
      class certification is denied; (ii) the class is decertified; or (iii) the
      customer  is excluded  from the class by the court.  Such  forbearance  to
      enforce an  agreement to  arbitrate  shall not  constitute a waiver of any
      rights under this agreement except to the extent stated herein.

15.   NEW  YORK LAW TO  GOVERN.  This  Agreement  and its  enforcement  shall be
      governed  by the  laws of the  State of New York  (without  regard  to any
      principles of conflicts of law) and its  provisions  shall be  continuous;
      shall cover  individually and collectively all accounts which you may open
      or  reopen  with  us,  and  shall  inure  to the  benefit  of our  present
      organization,  and any successor organization,  irrespective of any change
      or changes at any time in the personnel thereof, for any cause whatsoever,
      and of the assigns of our present organization

                               Page 19 of 24 Pages





      or any successor organization,  and shall be binding upon you, and/or your
      estate, executors, administrators, heirs and assigns.

16.   PARTIAL  UNENFORCEABILITY.  If any  provision  herein is or should  become
      inconsistent  with any present or future law,  rule or  regulation  of any
      sovereign  government or a regulatory  body having  jurisdiction  over the
      subject  matter  of  this  Agreement  or is held  to be  invalid,  void or
      unenforceable by reason of any law, rule, administrative order or judicial
      decision,  such  provision  shall be deemed to be rescinded or modified in
      accordance with any such law, rule, regulation,  order or decision. In all
      other respects, this Agreement shall continue and remain in full force and
      effect.

17.   LIMIT ORDERS. Montgomery Securities reserves the right to not accept from
      customers limit orders in NASDAQ or  over-the-counter  securities in which
      it acts as a market maker.


18.   MARGIN IN MARGIN ACCOUNTS (NOT APPLICABLE TO CASH ACCOUNTS). You hereby 
      agree to  maintain  such  margin  in your  margin  account  as  Montgomery
      Securities may in its discretion require and you agree to pay forthwith on
      demand  any  debit  balance  owing  with  respect  to any of  your  margin
      accounts,  and if not paid this  shall be a breach of this  Agreement  and
      Montgomery  Securities may take such action as it considers  necessary for
      its protection in accordance  with this  Agreement.  You understand  that,
      even if Montgomery Securities has a policy of giving customers notice of a
      margin  deficiency,  Montgomery  Securities  is not  obligated  to request
      additional  margin  from  you,  and  there  may  be  circumstances   where
      Montgomery  Securities will liquidate  securities and/or other property in
      your account  without notice to you. You will be charged  interest on your
      debit balance which if not paid at the close of an interest period will be
      added to the opening balance for the next interest period.  Please consult
      the attached disclosure statement for an outline of Montgomery Securities'
      interest policies.

19.   CUSTOMER'S CONSENT TO LOAN OR PLEDGE OF SECURITIES AND OTHER PROPERTY (NOT
      APPLICABLE TO CASH ACCOUNTS).  You hereby authorize Montgomery  Securities
      to lend either to itself or to others any  securities  and other  property
      held by Montgomery Securities in your margin account and to carry all such
      property in its general loans and such property may be pledged, repledged,
      hypothecated or  rehypothecated,  without notice to you, either separately
      or in common with other such  property  for any amounts due to  Montgomery
      Securities  thereon or for a greater sum, and Montgomery  Securities shall
      have no  obligation  to retain a like  amount of similar  property  in its
      possession and control.

      BY SIGNING THIS  AGREEMENT  YOU  ACKNOWLEDGE  THAT THE  SECURITIES IN YOUR
      MARGIN  ACCOUNT MAY BE LOANED TO  MONTGOMERY  SECURITIES  OR LOANED OUT TO
      OTHERS AND THAT YOU HAVE RECEIVED AND REVIEWED A COPY OF THIS AGREEMENT.

      THIS AGREEMENT  CONTAINS A PRE-DISPUTE  ARBITRATION CLAUSE AT PAGES 2-3 AT
      PARAGRAPH 14.

      IF JOINT  ACCOUNT  BOTH PARTIES  MUST SIGN.  Persons  signing on behalf of
      others please indicate title or capacity in which you have signed.

            Judith Segall
- ------------------------------------------------
            (Typed or Printed Name)

            /s/: Judith Segall
- ------------------------------------------------
                  (Signature)


- ------------------------------------------------
                  (Signature)

                               Page 20 of 24 Pages




c/o BioTime, Inc., 935 Pardee Street
- ------------------------------------------------
               (Mailing Address)

     Berkeley,           CA             94710
- ------------------------------------------------
        (City)         (State)           (Zip)

                    9/12/97
- ------------------------------------------------
                       (Date)


Acct.     XXX-XXXXX-XXX
No.:____________________________________________


                               Page 21 of 24 Pages






                         ADDENDUM TO CUSTOMER AGREEMENT



      Hypothecation of Customer Securities. Notwithstanding any provision of the
Customer Agreement to the contrary, Montgomery Securities shall not lend, pledge
or hypothecate any securities owned by Customer  (whether or not such securities
are held by Montgomery  Securities as Collateral for Customer's  Obligations) to
facilitate any short sale or otherwise;  provided, that this provision shall not
prevent the sale of Collateral pursuant to Section 4.

      Death or  Incompetency  of Customer.  Montgomery  Securities will not take
action  pursuant  to Section 4 solely  because of  Customer's  death or adjudged
incompetency if either (a) within 30 days after the date of Customer's  death or
declaration  of  incompetency  and  an  administrator,   executor,  conservator,
guardian or other  personal  representative  has  authority  to make  investment
decisions with respect to Customer's  account, or (b) with respect to Customer's
incompetency,   Customer  has  executed  a  power  of  attorney  designating  an
attorney-in-fact  who shall  have the power to make  investment  decisions  with
respect to Customer's account.



/s/: Judith Segall                            /s/: Wilson T. Hileman
- ----------------------------               ------------------------------
Customer Signature                            For Montgomery Securities

Judith Segall                              Wilson T. Hileman, Managing Director
- ----------------------------               ------------------------------------
Print Name                                    Print Name and Title

            XXX-XXXXX-XXX
Account No._________________



                               Page 22 of 24 Pages




                                                                     Exhibit (d)


                Representation letter FOR AFFILIATES of a Company
                  whose Stock is used as collateral for Margin




         Montgomery Securities
         600 Montgomery Street
         San Francisco, CA 94111.

         Attn:    Margin Department

         Gentlemen:

                  Reference  is made to the Customer  Agreement I executed  with
         you, pursuant to which you opened and maintain account number XXX-XXXXX
         for me, and which  agreement  governs the extension and  maintenance of
         margin credit with respect to such account.

                  I am an  affiliate  (as  defined in Rule 144 (a) (1) under the
         Securities Act of 1933 (the "Act") of Biotime, Inc. (the "Company").  I
         wish to obtain  margin  credit on not more  than  58,345  shares of the
         common stock (the  "Securities")  of the Company.  I understand that in
         order for you to extend margin credit to me which is  collateralized by
         the  Securities,  you must be able to sell the  Securities  pursuant to
         Rule  144  of  the  Act  ("Rule  14+"),  which  requires  that  certain
         conditions  must be met.  Accordingly,  I hereby  represent  to you and
         covenant with you as follows:

         1.   I acquired and fully paid for the  Securities on January 18, 1991.
              The Securities are "restricted  securities"  within the meaning of
              Rule  144,  and  bear  a  legend  describing  restrictions  on the
              transfer of the Securities.

         2.   In the  preceding  three  months,  I,  together  with all persons
              who are  considered  the same "person" as me under Rule  l44(a)(2)
              and all persons whose sales must be aggregated  with mine pursuant
              to Rule  144(e)(3),  have  sold 0 shares  of  common  stock of the
              Company. - --------------------------------------

         3.   The Securities, together with all shares of capital stock of the
              Company held by persons whose sales would be aggregated with sales
              by me  pursuant  to Rule 1  4+(e)(3),  constitute  less  -than the
              greater  of (i) 1% of the  shares of common  stock of the  Company
              currently  outstanding or (ii) the average weekly  reported volume
              of  trading  in the Common  Stock of the  Company on all  national
              securities  exchanges,  through the Nasdaq Stock Market, Inc., and
              /or through the consolidated

                               Page 23 of 24 Pages




              transaction reporting system. I agree that for the duration of the
              period for which my margin loan from Montgomery is collateralized,
              in whole or in part,  by the  Securities,  I will not transfer any
              shares of capital  stock of the Company to any person  whose sales
              would be aggregated with sales by me pursuant to Rule l44(e)(3).

         4.   I agree that for the  duration  of the period for which my margin
              loan from Montgomery Securities is collateralized,  in whole or in
              part,  by the  Securities,  I will not sell,  and I will cause all
              persons  who are  considered  the same  "person"  as me under Rule
              l44(a)(2) not to sell, any shares of common stock of the Company.

         5.   I will not use any margin credit to purchase  securities of any
              other company of which lam an affiliate (as defined in Rule 144(a)
              (1)).

         6.   I have no outstanding borrowing  collateralized by any shares of
              capital  stock of the Company and I will not incur such  borrowing
              from any other  person for the duration of the period for which my
              margin loan from Montgomery Securities is collateralized, in whole
              or in part, by the Securities.

         7.   I have  delivered  to you an  executed  Form  144,  a  Seller's
              Representation  Letter under Rule 144 and such other  documents as
              you have requested to enable you to sell the Securities under Rule
              144 at any time you may consider it necessary for your protection.
              The information  contained in these documents is true and correct.
              You may rely on the continued  accuracy and  completeness  of such
              information  unless and until I have informed you m writing of any
              changes to such  information  and have provided you with corrected
              versions  of such  documents I will not take any action or omit to
              take any action that would prevent you from selling the Securities
              at any time pursuant to Rule 144.

         8.   I will notify you  immediately  of any  occurrence  which would
              render any of the foregoing representations inaccurate.

         9.   I am  familiar  with  the  provisions  of  Section  16 of  the
              Securities   Exchange  Act  of  1934  and  the  rules  promulgated
              thereunder.  I understand the possible  consequences  to me if you
              sell the  Securities  at a time when such sale  would  deem 'me to
              have received  "short-swing"  profits,  which  consequences  could
              include the payment to the Company by me of all such profits.

The Company, its transfer agent and their agents and representatives may rely on
this letter. I will indemnify you and hold you harmless from and against any and
all loss, damage, claim,  liability and expense arising out of or resulting from
the breach of any representation or covenant herein.

Very truly yours,

Judith Segall

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