THE  SECURITY  REPRESENTED  HEREBY  HAS NOT BEEN  REGISTERED  UNDER THE
SECURITIES ACT OF 1933, AS AMENDED,  OR APPLICABLE  STATE  SECURITIES LAWS. THIS
SECURITY  MAY  NOT  BE  SOLD,  ASSIGNED  OR  TRANSFERRED  WITHOUT  AN  EFFECTIVE
REGISTRATION  STATEMENT FOR SUCH SECURITY  UNDER THE  SECURITIES ACT OF 1933, AS
AMENDED,  OR APPLICABLE STATE  SECURITIES LAWS,  UNLESS THE COMPANY HAS RECEIVED
THE  WRITTEN  OPINION OF COUNSEL  SATISFACTORY  TO THE  COMPANY  THAT SUCH SALE,
ASSIGNMENT OR TRANSFER DOES NOT INVOLVE A TRANSACTION REQUIRING  REGISTRATION OF
SUCH SECURITY UNDER THE SECURITIES ACT OF 1933, AS AMENDED,  OR APPLICABLE STATE
SECURITIES LAWS.


WARRANT NO. : W-CS-4                                 RIGHT TO PURCHASE 41,000
                                                     SHARES OF COMMON STOCK OF
DECEMBER 10, 1996                                    DYNAGEN, INC.

         VOID UNLESS EXERCISED BEFORE 5:00 P.M., EASTERN DAYLIGHT SAVING
                           TIME ON DECEMBER 31, 2003.

                                  DYNAGEN, INC.

                          COMMON STOCK PURCHASE WARRANT


         DYNAGEN, INC., a Delaware corporation (the "COMPANY"), hereby certifies
that,  in  consideration  of the  payment  of $100  (receipt  of which is hereby
acknowledged), RICH THERIAULT is entitled, subject to the terms set forth below,
to purchase from the Company,  commencing December 10, 1996, at any time or from
time to time  before  5:00 p.m.,  Eastern  Daylight  Saving  Time,  on or before
December 31, 2003, 41,000 fully paid and non-assessable  shares of Common Stock,
$.01 par value,  of the Company,  at an exercise price per share equal to $1.44.
Such exercise  price per share as adjusted from time to time as herein  provided
is referred to herein as the "EXERCISE PRICE".  The number and character of such
shares of Common  Stock and the  Exercise  Price are  subject to  adjustment  as
provided  herein.  THIS WARRANT IS EXERCISABLE IN  INSTALLMENTS,  SUBJECT TO THE
SATISFACTION OF CERTAIN CONDITIONS AS SET FORTH IN SECTION 1.3 BELOW. NO PORTION
OF THIS WARRANT MAY BE EXERCISED UNLESS SUCH CONDITIONS HAVE BEEN SATISFIED WITH
RESPECT TO THE CONDITIONS REGARDING EXERCISABILITY.

         As used  herein  the  following  terms,  unless the  context  otherwise
requires, have the following respective meanings:

         (a)  The  term  "COMPANY"  shall  include  DynaGen,  Inc.,  a  Delaware
corporation,  and any corporation  which shall succeed or assume the obligations
of the Company hereunder.

         (b) The term "COMMON  STOCK"  includes (a) the Company's  Common Stock,
$.01 par value per share,  as  authorized,  (b) any other  capital  stock of any
class or classes  (however  designated)  of the Company,  authorized on or after
such date, the holders of which shall have the





                                      -2-

right,  without  limitation  as to  amount,  either  to all or to a share of the
balance of current  dividends  and  liquidating  dividends  after the payment of
dividends  and  distributions  on any shares  entitled  to  preference,  and the
holders of which shall ordinarily, in the absence of contingencies,  be entitled
to vote for the election of a majority of directors of the Company  (even though
the right so to vote has been suspended by the happening of such a contingency),
(c) any other securities into which or for which any of the securities described
in  (a)  or  (b)  may  be  converted   or  exchanged   pursuant  to  a  plan  of
recapitalization,  reorganization,  merger, sale of assets or otherwise,  or the
conversion of promissory notes or other obligations of the Company.

         (c) The term "OTHER  SECURITIES" refers to any stock (other than Common
Stock) and other  securities  of the Company or any other person  (corporate  or
otherwise)  which the holder of this  Warrant at any time shall be  entitled  to
receive,  or shall have received,  on the exercise of the Warrant, in lieu of or
in  addition  to Common  Stock,  or which at any time shall be issuable or shall
have been  issued in exchange  for or in  replacement  of Common  Stock or Other
Securities pursuant to Sections 3 or 4 or otherwise.

         1.       EXERCISE OF WARRANT.

                  1.1. FULL  EXERCISE.  This Warrant may be exercised in full by
the holder hereof by surrender of this Warrant, with the form of subscription at
the end hereof duly  executed by such  holder,  to the Company at its  principal
office,  accompanied by payment,  in cash or by certified or official bank check
payable to the order of the Company,  in the amount  obtained by multiplying the
number of shares of Common Stock for which this Warrant is then  exercisable  by
the Exercise Price then in effect.

                  1.2. PARTIAL  EXERCISE.  This Warrant may be exercised in part
by surrender of this Warrant in the manner and at the place  provided in Section
1.1 except that the amount payable by the holder on such partial  exercise shall
be the amount  obtained by multiplying  (a) the number of shares of Common Stock
designated  by the  holder  in the  subscription  at the end  hereof  by (b) the
Exercise Price then in effect.  On any such partial  exercise the Company at its
expense  will  forthwith  issue and  deliver  to or upon the order of the holder
hereof a new Warrant or Warrants of like tenor, in the name of the holder hereof
or as such holder (upon payment by such holder of any applicable transfer taxes)
may  request,  calling in the  aggregate  on the face or faces  thereof  for the
number of shares of Common Stock for which such Warrant or Warrants may still be
exercised.

                  1.3  CONDITIONS  REGARDING  EXERCISABILITY.  Portions  of this
Warrant are exercisable  only upon the satisfaction of certain  conditions,  and
unlesss such  conditions  are  satisfied,  only that portion of this Warrant for
which the  conditions  have been  previously  satisfied  may be exercised at any
time.   The  Warrant  will  vest  and  become   exercisable   in  the  following
installments:  20% of the shares of Common  Stock under this  Warrant are vested
and exercisable upon delivery of the Warrant,  40% will become  exercisable upon
filing a 510(k)  or other  application  for the  BioLoc  Technology  or  DynaGen
Technology  with the FDA, and the  remaining  40% will become  exercisable  upon
approval of such  application  by the FDA;  provided,  however,  that the holder
continues to work on the BioLoc Technology or DynaGen  Technology and is engaged
by the Company as a consultant at the times of each of the foregoing milestones.
If the






                                      -3-

services  of the  holder of the  warrant  as a  consultant  to the  Company  are
terminated  without  cause,  then this  Warrant  shall  become  fully vested and
immediately  exercisable  at  the  time  of  any  FDA  application.  The  BioLoc
Technology  and DynaGen  Technology  is defined in a certain  Exclusive  License
Agreement  between the Company  and BioLoc,  Inc.  dated as of December 6, 1996.
DynaGen shall use  commercially  reasonable  efforts to file and prosecute  such
application with the FDA.

                  1.4 CASHLESS EXERCISE FEATURE -- RIGHT TO CONVERT WARRANT INTO
COMMON  STOCK.  (a) In  addition  to and  without  limiting  the  rights  of the
Warrantholder under the terms of this Warrant,  the Warrantholder shall have the
right (the  "CONVERSION  RIGHT") to convert this Warrant or any portion  thereof
into shares of Common Stock as provided in this Section at any time or from time
to time  prior to its  expiration,  subject  to the  restrictions  set  forth in
paragraph (c) hereof.  In lieu of exercising  this warrant for cash,  the holder
may elect to surrender  this  warrant for  conversion  and to receive  shares of
Common Stock equal to the value of this Warrant (or the portion being cancelled,
surrendered and converted) by surrender of this Warrant to the Company  together
with notice of such  election.  Upon such event,  the Company shall issue to the
holder a number of shares of the  Company's  Common Stock  computed by using the
following formula:
                         X  MINUS Y (A MINUS B)
                                        A
Where:            X = The  number of shares of Common  Stock to be issued to the
                      holder; 
                  Y = The number of shares of Common Stock  purchasable  under 
                      this  Warrant;  
                  A = The "Fair Market Value" of one share of the Common Stock;
                      and 
                  B = The Exercise Price of the Warrant (as adjusted to the date
                      of the calculation).

         Upon  exercise of the  Conversion  Right with  respect to a  particular
number of shares  subject to this  Warrant,  the  Company  shall  deliver to the
Warrantholder, without payment by the Warrantholder of any exercise price or any
cash or other consideration,  that number of shares of Common Stock equal to the
number  computed  using  the above  formula.  Notwithstanding  anything  in this
Section to the contrary,  the Conversion  Right cannot be exercised with respect
to a number  of  Converted  Warrant  Shares  having  a value  below  $1,000.  No
fractional  shares shall be issuable upon exercised of the Conversion Right, and
if the number of shares to be issued in accordance with the foregoing formula is
other than a whole number,  the Company shall pay to the Warrantholder an amount
in cash equal to the Fair Market Value of the resulting fractional share.

         (b) The Conversion  Right may be exercised by the  Warrantholder by the
surrender of this Warrant at the principal office of the Company together with a
written statement specifying that the Warrantholder  thereby intends to exercise
the  Conversion  Right and  indicating  the number of shares of Common  Stock or
authorized  Common Stock subject to this Warrant which are being  surrendered in
exercise of the  Conversion  Right.  Such  conversion  shall be  effective  upon
receipt by the  Company of this  Warrant  together  with the  aforesaid  written
statement,  or on such  later  date as is  specified  therein  (the  "CONVERSION
DATE"), but not later than the expiration date of this Warrant.





                                      -4-

         (c) In the event the Conversion  Right would,  at any time this Warrant
remains  outstanding,  be deemed by the Company's  independent  certified public
accountants  to give rise to a charge to the  Company's  earnings for  financial
reporting purposes, then the Conversion Right shall automatically terminate upon
the Company's  written notice to the  Warrantholder  of such adverse  accounting
treatment.

         (d) For purposes of this Section, the "FAIR MARKET VALUE" of a share of
Common  Stock  or  authorized   Common  Stock  as  of  a  particular  date  (the
"DETERMINATION DATE") shall mean:

                  (i) if the  Company's  Common  Stock  is  then  traded  on any
nationally-recognized  stock  exchange or quoted on the NASDAQ  National  Market
System or  Small-Cap  Market,  the average of the closing sale prices for the 20
trading days preceding the  Determination  Date, as reported by such exchange or
system,  as  reported  in The Wall  Street  Journal  or any  other  publication,
including the NASD;

                  (ii) if the  Company's  Common  Stock  is then  traded  on the
over-the-counter market, the average of the closing bid and closing asked prices
for the 30 trading days  preceding  the  Determination  Date, as reported in The
Wall Street Journal or by any market maker; or

                  (iii)  if  quotations  for  the  Company's   Common  Stock  or
authorized  Common  Stock is not readily  available  as set forth in (i) or (ii)
above, then as determined in good faith by the Company's Board of Directors upon
a review of all relevant factors,  including,  without limitation,  the price at
which  shares of the  Company's  Common Stock or  authorized  Common Stock could
reasonably be expected to be sold in an arms-length transaction, for cash, other
than on an  installment  basis,  to a person not employed by,  controlled by, in
control of or under common control with the Company,  which determination by the
Board of Directors shall give due consideration to recent transactions involving
shares of the Common Stock or  authorized  Common  Stock,  if any,  revenues and
earnings of the Company to the date of such  determination  (if any),  projected
revenues and earnings of the Company, the effect of the transfer restrictions to
which the shares are subject  under law, the absence of a public  market for the
Common Stock or authorized  Common Stock, and such other matters as the Board of
Directors deems pertinent. Such determination by the Board of Directors shall be
conclusive and binding.

         2. DELIVERY OF STOCK  CERTIFICATES ON EXERCISE.  As soon as practicable
after the exercise of this  Warrant in full or in part,  and in any event within
thirty (30) days thereafter,  the Company at its expense  (including the payment
by it of any applicable  issue taxes) will cause to be issued in the name of and
delivered to the holder  hereof,  or as such holder (upon payment by such holder
of any applicable  transfer taxes) may direct, a certificate or certificates for
the number of fully  paid and  non-assessable  shares of Common  Stock (or Other
Securities)  to which such holder shall be entitled on such  exercise,  plus, in
lieu of any fractional  share to which such holder would  otherwise be entitled,
cash equal to such fraction  multiplied by the then current  market value of one
full share.






                                      -5-

         3.       ADJUSTMENT FOR REORGANIZATION, CONSOLIDATION OR MERGER.

                  3.1.  REORGANIZATION,  CONSOLIDATION OR MERGER. In case at any
time or from time to time,  the Company shall (a) effect a  reorganization,  (b)
consolidate  with or merge into any other person or entity,  or (c) transfer all
or  substantially  all of its capital  stock,  properties or assets to any other
person  under  any plan or  arrangement  contemplating  the  dissolution  of the
Company,  then, in each such case,  the holder of this Warrant,  on the exercise
hereof as  provided  in  Section 1 at any time  after the  consummation  of such
reorganization,   consolidation   or  merger  or  the  effective  date  of  such
dissolution,  as the case may be,  shall  receive,  upon the proper and rightful
exercise  of this  Warrant,  in lieu of the Common  Stock (or Other  Securities)
issuable on such exercise prior to such consummation or such effective date, the
stock and other  securities and property  (including  cash) to which such holder
would have been  entitled  upon such  consummation  or in  connection  with such
dissolution,  as the case may be, if such holder had so exercised  this Warrant,
immediately  prior  thereto,  all subject to further  adjustment  thereafter  as
provided in Sections 4 and 5.

                  3.2.  CONTINUATION OF TERMS. Upon any corporate event referred
to in this Section 3, this Warrant  shall  continue in full force and effect and
the terms hereof shall be applicable to the shares of stock and Other Securities
and property  receivable on the exercise of this Warrant after the  consummation
of such  reorganization,  consolidation or merger, as the case may be, and shall
be binding upon the issuer of any such stock or other securities.

         4. ADJUSTMENTS FOR STOCK DIVIDENDS AND STOCK SPLITS.  In the event that
the Company shall (i) issue additional  shares of the Common Stock as a dividend
or  other   distribution  on  outstanding   Common  Stock,  (ii)  subdivide  its
outstanding  shares of Common Stock, or (iii) combine its outstanding  shares of
the Common Stock into a smaller  number of shares of the Common Stock,  then, in
each such event, the Exercise Price shall,  simultaneously with the happening of
such event, be adjusted by multiplying  the then prevailing  Exercise Price by a
fraction,  the  numerator of which shall be the number of shares of Common Stock
outstanding  immediately prior to such event (calculated assuming the conversion
or exchange of all outstanding shares of convertible or exchangeable  securities
of the Company which are convertible or exchangeable  into, or exercisable  for,
shares of Common  Stock)  and the  denominator  of which  shall be the number of
shares of Common  Stock  outstanding  immediately  after such event  (calculated
assuming the conversion or exchange of all outstanding  shares of convertible or
exchangeable  securities of the Company which are  convertible  or  exchangeable
into, or exercisable  for, shares of Common Stock),  and the product so obtained
shall thereafter be the Exercise Price then in effect. The Exercise Price, as so
adjusted,  shall be  readjusted  in the same  manner upon the  happening  of any
successive  event or events  described  herein in this  Section 4. The holder of
this Warrant shall thereafter,  on the exercise hereof as provided in Section 1,
be  entitled  to receive  that number of shares of Common  Stock  determined  by
multiplying  the number of shares of Common Stock which would otherwise (but for
the provisions of this Section 4) be issuable on such exercise, by a fraction of
which (i) the numerator is the Exercise Price which would otherwise (but for the
provisions  of this  Section 4) be in effect,  and (ii) the  denominator  is the
Exercise Price in effect on the date of such exercise.






                                      -6-

         5.   ADJUSTMENT   FOR   DIVIDENDS   IN  OTHER   STOCK,   PROPERTY   AND
RECLASSIFICATIONS.  In case at any time or from  time to time,  the  holders  of
Common  Stock (or Other  Securities)  shall have  received,  or (on or after the
record date fixed for the  determination  of  stockholders  eligible to receive)
shall have become entitled to receive, without payment therefor,

         (a) other or additional  stock or other  securities or property  (other
than cash) by way of dividend, or

         (b)  other  or  additional   stock  or  other  securities  or  property
(including   cash)   by   way   of   spin-off,    split-up,    reclassification,
recapitalization, combination of shares or similar corporate rearrangement,

other than additional shares of Common Stock (or Other  Securities)  issued as a
stock dividend or in a stock-split (adjustments in respect of which, in the case
of Common Stock,  are provided for in Section 4), then and in each such case the
holder of this Warrant,  on the exercise  hereof as provided in Section 1, shall
be  entitled  to  receive  the  amount  of other or  additional  stock and other
securities and property  (including cash in the cases referred to in subdivision
(b) of this Section 5) which such holder would hold on the date of such exercise
if on the  date of  distribution  of such  other  or  additional  stock or other
securities  and  property,  or on the  record  date  fixed for  determining  the
shareholders  entitled  to  receive  such  other  or  additional  stock or other
securities and property, such holder had been the holder of record of the number
of  shares  of  Common  Stock  called  for on the face of this  Warrant  and had
thereafter, during the period from the date thereof to and including the date of
such exercise,  retained such shares and all such other or additional  stock and
other  securities  and  property  (including  cash in the cases  referred  to in
subdivision (b) of this Section 5) receivable by such holder as aforesaid during
such period,  giving effect to all adjustments  called for during such period by
Sections 3 and 4.

         6.       NOTICES OF RECORD DATE.  In the event of

         (a) any taking by the  Company of a record of the  holders of any class
or  securities  for the  purpose of  determining  the  holders  thereof  who are
entitled  to  receive  any  dividend  or  other  distribution,  or any  right to
subscribe for, purchase or otherwise acquire any shares of stock of any class or
any other securities or property, or to receive any other right, or

         (b) any capital  reorganization of the Company, any reclassification or
recapitalization  of the capital  stock of the Company or any transfer of all or
substantially all the assets of the Company to or consolidation or merger of the
Company with or into any other person, or

         (c) any voluntary or involuntary dissolution, liquidation or winding-up
of the Company,

then and in each such event the  Company  will mail or cause to be mailed to the
holder of this Warrant a notice specifying (i) the date on which any such record
is to be taken for the  purpose of such  dividend,  distribution  or right,  and
stating the amount and character of such dividend,  distribution  or right,  and
(ii)   the   date  on   which   any   such   reorganization,   reclassification,







                                      -7-

recapitalization,  transfer, consolidation,  merger, dissolution, liquidation or
winding-up is to take place,  and the time,  if any is to be fixed,  as of which
the holders of record of Common Stock (or Other Securities) shall be entitled to
exchange  their shares of Common Stock (or Other  Securities)  for securities or
other   property   deliverable   on   such   reorganization,   reclassification,
recapitalization,  transfer, consolidation,  merger, dissolution, liquidation or
winding-up.  Such notice  shall be mailed at least twenty (20) days prior to the
date specified in such notice on which any such action is to be taken.

         7.  RESERVATION OF STOCK  ISSUABLE ON EXERCISE OF WARRANT.  The Company
will at all times reserve and keep  available,  solely for issuance and delivery
on the  exercise of the  Warrant,  all shares of Common  Stock from time to time
issuable on the  exercise of the  Warrant;  the shares of Common Stock which the
holder of this Warrant  shall  receive upon exercise of the Warrant will be duly
authorized, validly issued, fully paid and non-assessable.

         8.  EXCHANGE OF WARRANT.  On surrender  for  exchange of this  Warrant,
properly  endorsed,  to the  Company,  the Company at its expense will issue and
deliver to or on the order of the holder  thereof a new  Warrant or  Warrants of
like  tenor,  in the name of such  holder or as such  holder (on payment by such
holder of any applicable transfer taxes) may direct, calling in the aggregate on
the face or faces thereof for the number of shares of Common Stock called for on
the face or faces of the Warrant or Warrants so surrendered.

         9.   REPLACEMENT  OF  WARRANT.   On  receipt  of  evidence   reasonably
satisfactory  to the Company of the loss,  theft,  destruction  or mutilation of
this Warrant  and, in the case of any such loss,  theft or  destruction  of this
Warrant,   on  delivery  of  an  indemnity   agreement  or  security  reasonably
satisfactory  in form and  amount  to the  Company  or,  in the case of any such
mutilation,  on surrender and  cancellation of such Warrant,  the Company at its
expense will execute and deliver, in lieu thereof, a new Warrant of like tenor.

         10.  WARRANTHOLDER  NOT DEEMED  STOCKHOLDER;  RESTRICTIONS ON TRANSFER.
This Warrant is issued upon the following  terms, to all of which each holder or
owner hereof by the taking hereof consents and agrees:

         (a) No holder of this Warrant  shall,  as such, be deemed the holder of
      Common  Stock  that  may at any time be  issuable  upon  exercise  of this
      Warrant for any purpose whatsoever, nor shall anything contained herein be
      construed  to confer  upon such  holder,  as such,  any of the rights of a
      stockholder of the Company until such holder shall have  delivered  formal
      notice to the Company of an intention to exercise this  Warrant,  tendered
      promptly  the  consideration   required  for  exercise  (whether  cash  or
      securities), exercised the Warrant, and been issued shares of Common Stock
      in accordance with the provisions hereof.

         (b)  Neither  this  Warrant  nor any shares of Common  Stock  purchased
      pursuant to this Warrant shall be registered  under the  Securities Act of
      1933  (the  "SECURITIES   ACT")  and  applicable  state  securities  laws.
      Therefore,  the  Company may  require,  as a  condition  of  allowing  the
      transfer or exchange of this  Warrant or such  shares,  that the holder or
      transferee of this Warrant or such shares,  as the case may be, furnish to
      the Company an opinion of 






                                      -8-

      counsel  acceptable  to the  Company to the effect  that such  transfer or
      exchange may be made without  registration  under the  Securities  Act and
      applicable state  securities laws. The certificates  evidencing the shares
      of Common Stock issued on the exercise of the Warrant  shall bear a legend
      to the effect that the shares evidenced by such certificates have not been
      registered under the Securities Act and applicable state securities laws.

         (c) This Warrant is not transferable or assignable to any party without
      the prior written consent of the Company, and accompanied by an opinion of
      counsel  satisfactory  to the Company  that such  transfer is  permissible
      under applicable law.

         11. NOTICES.  All notices and other  communications from the Company to
the holder of this  Warrant  shall be mailed by (i) first  class  mail,  postage
prepaid,  (ii) electronic  facsimile  transmission,  or (iii) express  overnight
courier  service,  at such address as may have been  furnished to the Company in
writing by such  holder or,  until any such holder  furnishes  to the Company an
address, then to, and at the address of, the last holder of this Warrant who has
so furnished an address to the Company.

         12.  MISCELLANEOUS.  This  Warrant  and any term hereof may be changed,
waived,  discharged or terminated only by an instrument in writing signed by the
party against which enforcement of such change, waiver, discharge or termination
is sought.  This Warrant and the shares of Common Stock  underlying this Warrant
shall be construed and enforced in  accordance  with and governed by the laws of
the State of Delaware.  The  invalidity  or  unenforceability  of any  provision
hereof  shall in no way  affect  the  validity  or  enforceability  of any other
provision.

         13.      REGISTRATION RIGHTS.

                  13.1 SHORT-FORM REGISTRATIONS ON FORM S-3. At such time when a
510(k) or other  application has been filed for the BioLoc Technology or DynaGen
Technology and this Warrant is at least sixty percent (60%) vested in accordance
with  Section  1.3, at the request of the  holders of at least  seventy  percent
(70%) of the shares of Common Stock  underlying  this Warrant (the  "REGISTRABLE
SHARES"),  the  Company  shall  use its  best  efforts  to  file a  registration
statement  on Form S-3 (to the extent  such form is  available  to the  Company)
covering the resale of the Shares  underlying  this  Warrant  (the  "REGISTRABLE
SHARES").  The  Company  will so  notify  each  holder  of  Registrable  Shares,
including each holder who has a right to acquire  Registrable  Shares,  and then
shall, as expeditiously  as possible (using  commercially  reasonable  efforts),
effect  qualification  and registration  under the Securities Act on Form S-3 of
all or such  portion of the  Registrable  Shares as the holder or holders  shall
specify,  and shall thereafter  maintain the  effectiveness of such Registration
Statement until such shares have been sold or until the registration  obligation
terminates under Section 13.3.

         The  Company  shall  not be  required  to  effect  more  than  one  (1)
registration  on Form S-3. The  Company's  obligations  under this Section shall
expire  three (3) years after the  issuance  date of this  Warrant.  The Company
agrees to qualify or register the Shares under  applicable  state law,  list the
shares wherever the Common Stock is then listed and supplement the prospectus as
necessary from time to time to keep it current.





                                      -9-


                  13.2  EXPENSES.  In the case of a  registration  under Section
13.1,  the Company  shall bear the  expenses of any filing of any  registration,
including but not limited to printing legal and accounting expenses,  Securities
and Exchange Commission and NASD filing fees and all related "Blue Sky" fees and
expenses; provided, however, that the Company shall have no obligation to pay or
otherwise  bear  any  portion  of the  underwriters'  commissions  or  discounts
attributable  to the  securities  being  offered  and sold by the holder of this
Warrant,  or the fees and  expenses of any  counsel,  tax advisor or  accountant
selected by such holder in connection with the registration of the securities.

                  13.3 EXPIRATION OF REGISTRATION RIGHTS. The obligations of the
Company  under this  Section 13 to  register  the  securities  shall  expire and
terminate  at such  time as the  holder of this  Warrant  shall be  entitled  or
eligible to sell the shares of Common  Stock  underlying  this  Warrant  without
restriction and without a need for the filing of a registration  statement under
the Securities Act of 1933,  including  without  limitation,  for any resales of
restricted securities made pursuant to Rule 144 as promulgated by the Securities
and Exchange Commission.

                  13.4  DELAY OF  REGISTRATION.  For a period  not to exceed 120
days,  the Company  shall not be obligated to prepare and file,  or be prevented
from delaying or abandoning,  a registration  statement pursuant to this Section
13 at any time when the Company, in its good faith judgment by the management of
the Company, with the advice of counsel, reasonably believes:

                           (I) that the filing thereof at the time requested, or
the offering of  Registrable  Shares  pursuant  thereto,  would  materially  and
adversely affect (a) a pending or scheduled public offering or private placement
of the  Company's  securities,  (b) an  acquisition,  merger,  consolidation  or
similar  transaction  by or of the  Company,  (c)  pre-existing  and  continuing
negotiations,  discussions  or  pending  proposals  with  respect  to any of the
foregoing transactions, or (d) the financial condition of the Company in view of
the  disclosure of any pending or threatened  litigation,  claim,  assessment or
governmental investigation which may be required thereby; and

                           (II)  that  the  failure  to  disclose  any  material
information  with  respect  to the  foregoing  would  cause a  violation  of the
Securities Act or the Securities Exchange Act of 1934.

                  13.5  INDEMNIFICATION OF HOLDERS OF REGISTRABLE SHARES. In the
event  that the  Company  registers  any of the  Registrable  Shares  under  the
Securities  Act, the Company will  indemnify  and hold  harmless each holder and
each underwriter of the Registrable Shares (including their officers, directors,
affiliates  and partners) so registered  (including any broker or dealer through
whom such shares may be sold) and each person,  if any, who controls such holder
or any such  underwriter  within the meaning of Section 15 of the Securities Act
from and against any and all losses, claims,  damages,  expenses or liabilities,
joint  or  several,  to  which  they or any of them  become  subject  under  the
Securities Act,  applicable  state securities laws or under any other statute or
at common law or otherwise,  as incurred,  and, except as hereinafter  provided,
will reimburse each such holder, each such underwriter and each such controlling
person, if any, 






                                      -10-


for any legal or other  expenses  reasonably  incurred by them or any of them in
connection with  investigating or defending any actions whether or not resulting
in any liability, insofar as such losses, claims, damages, expenses, liabilities
or actions arise out of or are based upon any untrue statement or alleged untrue
statement of a material fact contained in the registration statement under which
such Securities were registered under the Securities Act, in any filing with any
state securities commission in any preliminary or amended preliminary prospectus
or in the final prospectus (or the registration  statement or prospectus as from
time to time amended or  supplemented  by the  Company),  or arise out of or are
based upon the  omission or alleged  omission to state  therein a material  fact
required  to be stated  therein  or  necessary  in order to make the  statements
therein,  in the  light  of the  circumstances  in which  they  were  made,  not
misleading,  or  any  violation  by  the  Company  of  any  rule  or  regulation
promulgated  under the Securities Act or any state securities laws applicable to
the  Company  and  relating  to action or  inaction  required  of the Company in
connection with such registration.

         Notwithstanding the foregoing,  the Company shall have no obligation to
indemnify  any holder,  underwriter  or  controlling  person if: (i) such untrue
statement or omission was made in such  registration  statement,  preliminary or
amended  preliminary  prospectus  or final  prospectus  in reliance  upon and in
conformity  with  information  furnished in writing to the Company in connection
therewith by such holder of Registrable  Shares (in the case of  indemnification
of such  holder),  such  underwriter  (in the  case of  indemnification  of such
underwriter) or such controlling  person (in the case of indemnification of such
controlling  person)  expressly  for use therein,  or (ii) in the case of a sale
directly  by  such  holder  of  Registrable  Shares  (including  a sale  of such
Registrable   Shares  through  any  underwriter   retained  by  such  holder  of
Registrable  Shares to engage in a distribution  solely on behalf of such holder
of Registrable  Shares),  such untrue  statement or alleged untrue  statement or
omission or alleged  omission was  contained  in a  preliminary  prospectus  and
corrected  in a final or amended  prospectus  copies of which were  delivered to
such holder of Registrable  Shares or such  underwriter  on a timely basis,  and
such  holder of  Registrable  Shares  failed  to  deliver a copy of the final or
amended  prospectus  at or  prior  to  the  confirmation  of  the  sale  of  the
Registrable  Shares to the  person  asserting  any such loss,  claim,  damage or
liability in any case where such delivery is required by the Securities Act.

         14. EXPIRATION. The right to exercise this Warrant shall expire at 5:00
p.m., Eastern Daylight Saving Time, on December 31, 2003.

Dated: December 12, 1996                DYNAGEN, INC.


ATTEST:

By: /s/ John M. Hession                 By: /s/ Dhananjay G. Wadekar

Title: Secretary                        Title: Executive Vice President









                              FORM OF SUBSCRIPTION
                   (TO BE SIGNED ONLY ON EXERCISE OF WARRANT)


TO DynaGen, Inc.

         The undersigned,  the holder of the within Warrant,  hereby irrevocably
elects to exercise this Warrant for, and to purchase thereunder, ........ shares
of Common Stock of DynaGen,  Inc., a Delaware  corporation,  and herewith  makes
payment of $........  therefor,  and  requests  that the  certificates  for such
shares be issued in the name of, and delivered to ..............,  whose address
is ................................

Dated:
                                     (Signature must conform to name of holder 
                                      as specified on the face of the Warrant)


                                     (Address)

                                    --------------------

                               FORM OF ASSIGNMENT
                   (TO BE SIGNED ONLY ON TRANSFER OF WARRANT)


         For  value  received,   the  undersigned  hereby  sells,  assigns,  and
transfers unto .................. the right represented by the within Warrant to
purchase  .............  shares of Common  Stock of  DynaGen,  Inc.,  a Delaware
corporation,    to   which   the   within   Warrant   relates,    and   appoints
 ..........................  Attorney  to  transfer  such  right on the  books of
DynaGen,  Inc., a Delaware  corporation,  with full power of substitution in the
premises.


Dated:
                                       (Signature must conform to name of holder
                                        as specified on the face of the Warrant)


                                            (Address)

Signed in the presence of:                                  
 .............................