EXHIBIT 3.3

                         REGISTRATION RIGHTS AGREEMENT

This Agreement is made as of the 18th day of December, 1996.

B E T W E E N:
         
         
         NEUROSCIENCE PARTNERS LIMITED PARTNERSHIP, 
         a limited partnership constituted under the laws of the Province of
         Ontario
         
                                   - and -


         APOLLO GENETICS, INC., 
         a corporation subsisting under the laws of Delaware


RECITALS:

1.  Apollo and the Fund have entered into a Royalty Purchase Agreement (the
    "Royalty Agreement") of even date herewith.

2.  Pursuant to the Royalty Agreement, the Fund will purchase Apollo Common
    Shares, warrants to purchase Apollo Common Shares and a right to convert
    future Royalties into Apollo Common Shares.

3.  Pursuant to the Royalty Agreement, Apollo has agreed to enter into this
    Registration Rights Agreement.

IN CONSIDERATION of the premises, the mutual covenants in this agreement and of
other good and valuable consideration (the receipt and sufficiency of which are
acknowledged by each Party), the Parties agree as follows:

1.  CERTAIN DEFINITIONS.  As used in this Agreement, terms defined in the
Royalty Agreement not otherwise defined herein shall have the respective
meanings assigned thereto in the Royalty Agreement.  In addition, the following
terms shall have the following respective meanings:



                                      -2-

    "ACT" shall mean the SECURITIES ACT of 1933, as amended;

    "AGREEMENT" means this agreement, the recitals, all attached schedules and
    any agreement, exhibit or schedule supplementing or amending this
    agreement.  All uses of the words "hereto", "herein," "hereof," "hereby"
    and "hereunder" and similar expressions refer to this Agreement and not to
    any particular section or portion of it.  References to an Article,
    Section, Subsection, Exhibit or Schedule refer to the applicable article,
    section, subsection, exhibit or schedule of this Agreement;

    "COMMISSION" shall mean the Securities and Exchange Commission or any other
    federal agency at the time administering the Act;

    "COMPANY" shall mean Apollo;

    "HOLDER" shall mean the Fund holding Registrable Securities and any other
    Person holding Registrable Securities to whom the rights under this
    Agreement have been transferred in accordance with Section 10 hereof;

    "INITIAL PUBLIC OFFERING" shall mean the initial public offering of the
    Company, a reverse take-over or any other event pursuant to which
    securities of the Company become listed and posted for trading on any stock
    exchange or qualified for unlisted trading privileges on any trade
    reporting and quotation system for over-the-counter trading;

    "INITIATING HOLDER" shall mean any Holder or Holders who, in the aggregate,
    hold not less than twenty-five percent (25%) of the outstanding Registrable
    Securities;

    "REGISTER", "REGISTERED" and "REGISTRATION" shall refer to a registration
    statement in compliance with the Act, and the declaration or ordering of
    the effectiveness of such registration statement;

    "REGISTRABLE SECURITIES" shall mean the Shares and any Apollo Common Shares
    or other securities issued or issuable with respect to the Shares upon any
    stock split, stock dividend, recapitalization, or similar event, or any
    Apollo Common Shares otherwise issued or issuable with respect to the
    Shares, provided, however, that Apollo Common Shares or other securities
    shall only be treated as Registrable securities if and so long as they have
    not been sold to or through a broker or dealer or underwriter' in a public
    distribution or a public securities transaction;



                                     -3-

    "REGISTRATION EXPENSES" shall mean all expenses, except Selling Expenses,
    incurred by the Company in complying with paragraphs 2, 3 and 4 hereof,
    including, without limitation, all registration, qualification and filing
    fees, printing expenses, escrow fees, fees and disbursements of counsel for
    the Company, blue sky fees and expenses, the expense of any special audits
    incidental to or required by any such registration (but excluding the
    compensation of regular employees of the Company which shall be paid in any
    event by the Company and the fees and expenses of counsel for the Holders);

    "RESTRICTED SECURITIES" shall mean the securities of Apollo that are
    restricted securities under the SECURITIES ACT and applicable state
    securities laws;

    "SELLING EXPENSES" shall mean all underwriting discounts, selling
    commissions and stock transfer taxes applicable to the securities
    registered by the Holder and fees and expenses of counsel for the Holder;

    "SHARES" shall mean: (i) the Apollo Common Shares issued to the Fund
    pursuant to the Subscription Agreement; (ii) the Apollo Common Shares
    issuable upon exercise of the Warrants; and (iii) the Apollo Common Shares
    issuable upon exercise of the Conversion Right;

    "SUBSCRIPTION AGREEMENT" shall mean the Subscription Agreement between
    Apollo and the Fund dated of even date herewith; and

    "WARRANTS" shall mean the $.70 warrants and the $.875 Warrants,
    collectively.

2.  COMPANY REGISTRATION.

    (a)  NOTICE OF REGISTRATION.  If at any time or from time to time after the
    completion date of the Company's Initial Public Offering, the Company shall
    determine to register any of its securities, either for its own account or
    the account of a securityholder or holders (other than pursuant to Section
    3 of this Agreement), other than (i) a registration relating solely to
    employee benefit plans, or (ii) a registration relating solely to a
    Commission Rule 145 transaction, the Company will:

         (i)  promptly give to any Holder written notice thereof; and


                                     -4-

         (ii) include in such registration (and any related qualification under
         blue sky laws or other compliance), and in any underwriting involved
         therein, all the Registrable Securities specified in a written request
         or requests, made within 20 days after receipt of such written notice
         from the Company, by any Holder.

    (b)  UNDERWRITING.  If the registration of which the Company gives notice
    is for a registered public offering involving an underwriting, the Company
    shall so advise any Holder as a part of the written notice given pursuant
    to Section 2(a)(i).  In such event the right of any Holder to registration
    pursuant to this paragraph 2 shall be conditioned upon such Holder's
    participation in such underwriting and the inclusion of Registrable
    Securities in the underwriting to the extent provided herein.  All Holders
    proposing to distribute their securities through such underwriting shall
    (together with the Company and the other holders distributing their
    securities through such underwriting) enter into an underwriting agreement
    in customary form with the managing underwriter selected for such
    underwriting by the Company.

    Notwithstanding any other provision of this Section 2, if the managing
    underwriter determines that marketing factors require a limitation of the
    number of shares to be underwritten, the managing underwriter may limit the
    number of Registrable Securities and other securities to be included in
    such registration or exclude them entirely.  The Company shall advise any
    Holder distributing its securities through such underwriting of the
    managing underwriter's limitation and the number of Shares of Registrable
    Securities and other securities that may be included in the underwriting
    (the "Other Shares").  The Other Shares shall be allocated among the
    Holders of Registrable Securities and the holders of other securities, if
    more than one, in proportion, as nearly as practicable, to the respective
    amounts of Registrable Securities and other securities held by such Holders
    and holders at the time of filing the registration statement.  To
    facilitate the allocation of securities in accordance with the above
    provisions, the Company may round the number of securities allocated to any
    Holder or holder to the nearest 100 shares.
    
    If any Holder disapproves of the terms of any such underwriting, he may
    elect to withdraw therefrom by written notice to the Company and the
    managing underwriter.  Any securities excluded or withdrawn from such
    underwriting shall be withdrawn from such registration, and shall not be
    transferred in a public distribution prior to 90 days after the effective
    date of the registration statement relating to the


                                     -5-

    underwriting, or such other shorter period of time as the underwriters may 
    require.

    (c)  RIGHT TO TERMINATE REGISTRATION.  The Company shall have the right to
    terminate or withdraw any registration initiated by it under this Section 2
    prior to the effectiveness of such registration whether or not any Holder
    has elected to include Registrable Securities in such registration.

3.  REQUESTED REGISTRATION.

    (a)  REQUEST FOR REGISTRATION.  In case the Company shall receive from any
    Initiating Holders a written request that the Company effect a
    registration: (i) at any time 13 months after the completion date of the
    Company's Initial Public Offering, with respect to a maximum of 714,429
    Registrable Securities; and (ii) at any time 25 months after the completion
    of the Company's Initial Public Offering, with respect to all of the
    Registrable Securities, the Company will as soon as practicable, use its
    best efforts to effect such registration (including, without limitation,
    appropriate qualification under applicable blue sky or other state or
    provincial securities laws and appropriate compliance with applicable
    regulations issued under the Act and any other governmental requirements or
    regulations) as may be so requested and as would permit or facilitate the
    sale and distribution of all or such portion of such Registrable Securities
    as are specified in such request.
    
    The Company shall not be obligated to effect, or to take any action to
    effect, any such registration pursuant to this Section 3:
    
         (i)  in any particular jurisdiction in which the Company would be
         required to execute a general consent to service of process in
         effecting such registration, qualification, or compliance, unless the
         Company is already subject to service in such jurisdiction and except
         as may be required by the Securities Act, it being acknowledged and
         agreed that the Company is not restricted from effecting a
         registration in California, Illinois, Massachusetts, Minnesota and New
         York by virtue of this Section 3(a)(ii);
         
         (ii) after the Company has initiated two such registrations pursuant
         to this Section 3 (counting for these purposes only registrations
         which have been declared or ordered effective and pursuant to which
         securities have been sold and registrations which have been withdrawn
         by the Holders as to which the



                                     -6-

         Holders have not elected to bear the Registration Expenses pursuant to
         Section 5 hereof and would, absent such election, have been required 
         to bear such expenses);
         
         (iii) during the period starting with the date sixty (60) days
         prior to the Company's good faith estimate of the date of filing of,
         and ending on a date one hundred eighty (180) days after the effective
         date of, a Company-initiated registration; provided that the Company
         is actively employing in good faith all reasonable efforts to cause
         such registration statement to become effective; and
         
         (iv) if the Initiating Holders propose to dispose of shares of
         Registrable Securities which may be immediately registered on Form S-3
         pursuant to a request made under Section 4 hereof.
    
    Subject to the foregoing clauses (i) to (iv), the Company shall file a
    registration statement covering the Registrable Securities so requested to
    be registered as soon as practicable after receipt of the request of any
    Holder and in any event within one hundred twenty (120) days after receipt
    of such request; provided, however, that if (i) in the good faith judgment
    of the Board of Directors of the Company, such registration would be
    seriously detrimental to the Company and the Board of Directors of the
    Company concludes, as a result, that it is essential to defer the filing of
    such registration statement at such time, and (ii) the Company shall
    furnish to Holders a certificate signed by the President of the Company
    stating that in the good faith judgment of the Board of Directors of the
    Company, it would be seriously detrimental to the Company for such
    registration statement to be filed in the near future and it is, therefore,
    essential to defer the filing of such registration statement, then the
    Company shall have the right to defer such filing for a period of not more
    than ninety (90) days after receipt of the request of the Initiating
    Holders, and, provided further, that the Company shall not defer its
    obligation in this manner more than once in any twelve-month period.

    (b)  UNDERWRITING.  In the event that a registration pursuant to this
    Section 3 is for a registered public offering involving an underwriting,
    the Company shall so advise the Holder.  In such event, the right of any
    Holder to such registration shall be conditioned upon such Holder's
    participation in the underwriting arrangements required by this Section 3,
    and the inclusion of such Holder's Registrable Securities in the
    underwriting to the extent requested shall be limited to the extent
    provided herein.


                                     -7-

    The Company shall (together with any Holders proposing to distribute their
    securities through such underwriting) enter into an underwriting agreement
    in customary form with the managing underwriter selected for such
    underwriting by the Initiating Holders, but subject to the Company's
    reasonable approval.  Notwithstanding any other provision of this Section
    3, if the managing underwriter advises the Holder in writing that marketing
    factors require a limitation of the number of shares to be underwritten,
    then the number of Registrable Securities that may be included in the
    registration and underwriting shall be equal to the number specified by the
    underwriter, provided, however, that the number of shares of Registrable
    Securities to be included in such underwriting shall not be reduced unless
    all other securities are first entirely excluded from the underwriting.  No
    Registrable Securities excluded from the underwriting by reason of the
    underwriter's marketing limitation shall be included in such registration.  
    
    If the Holder of Registrable Securities disapproves of the terms of the
    underwriting, the Holder may elect to withdraw therefrom by written notice
    to the Company and the managing underwriter.  The Registrable Securities
    and/or other securities so withdrawn shall also be withdrawn from
    registration, and such Registrable Securities shall not be transferred in a
    public distribution prior to 90 days after the effective date of such
    registration, or such other shorter period of time as the underwriters may
    require.

4.  REGISTRATION ON FORM S-3.   If any Holder requests that the Company file 
a registration statement on Form S-3 (or any successor form to Form S-3) for 
a public offering of shares of the Registrable Securities the reasonably 
anticipated aggregate price to the public of which, net of underwriting 
discounts and commissions, would exceed $500,000, and the Company is a 
registrant entitled to use Form S-3 to register the Registrable Securities 
for such an offering, the Company shall use its best efforts to cause such 
Registrable Securities to be registered for the offering on such form and to 
cause such Registrable Securities to be qualified in such jurisdictions as 
any Holder may reasonably request.  Provided, however, that the Company shall 
not be required to effect more than one registration pursuant to this Section 
4 in any calendar year.  The substantive provisions of Section 3(b) shall be 
applicable to each registration under this Section 4.

5.  EXPENSES OF REGISTRATION.  All Registration Expenses incurred in connection
with all registrations pursuant to this Agreement shall be borne by the Company;
provided, however, that if the Holders bear the Registration


                                     -8-

Expenses for any registration proceeding begun pursuant to Section 3 and 
subsequently withdrawn by the Holders registering shares therein, such 
registration proceeding shall not be counted as a requested registration 
pursuant to Section 3 hereof; and provided further, however, that: (i) if at 
the time of such withdrawal, the Holders have learned of a material adverse 
event with respect to the condition, business or prospects of the Company not 
known to the Holders at the time of their request; or (ii) such withdrawal is 
made after a deferral of such registration by the Company pursuant to Section 
3(a), then the Holders shall not be required to pay any of such expenses and 
such registration proceeding shall not be counted as a requested registration 
pursuant to Section 3 hereof.  All Selling Expenses relating to securities so 
registered shall be borne by the Holders of such securities pro rata on the 
basis of the number of shares of securities so registered on their behalf, as 
shall any other expenses in connection with the registration required to be 
borne by the Holders of such securities.

6.  REGISTRATION PROCEDURES.  In the case of each registration, qualification
or compliance effected by the Company pursuant to this Agreement, the Company
will keep any Holder advised in writing as to the initiation of each
registration, qualification and compliance and as to the completion thereof.  At
its expense, the Company will:

    (a)  Prepare and file with the Commission a registration statement with
    respect to such securities and use its best efforts to cause such
    registration statement to become and remain effective for at least sixty
    (60) days or until the distribution described in the Registration Statement
    has been completed.
    
    (b)  Prepare and file with the Commission such amendments and supplements
    to such registration statement and the prospectus used in connection with
    such registration statement as may be necessary to comply with the
    provisions of the Act with respect to the disposition of all securities
    covered by such registration statement.
    
    (c)  Furnish to any Holder such numbers of copies of a prospectus,
    including a preliminary prospectus, in conformity with the requirements of
    the Act, and such other documents as they may reasonably request in order
    to facilitate the disposition of Registrable Securities owned by him.
    
    (d)  Use its best efforts to register and qualify the securities covered by
    such registration statement under such other securities or Blue Sky laws of
    such jurisdictions as shall be reasonably requested by any Holder.  


                                     -9-

    (e)  In the event of any underwritten public offering, enter into and
    perform its obligations under an underwriting agreement, in usual and
    customary form, with the managing underwriter of such offering.  Any Holder
    participating in such underwriting shall also enter into and perform its
    obligations under such an agreement.

    (f)  Notify any Holder of Registrable Securities covered by such
    registration statement at any time when a prospectus relating thereto is
    required to be delivered under the Act of the happening of any event as a
    result of which the prospectus included in such registration statement, as
    then in effect, includes an untrue statement of a material fact or omits to
    state a material fact required to be stated therein or necessary to make
    the statements therein not misleading in the light of the circumstances
    then existing.

    (g)  Furnish, at the request of any Holder requesting registration of
    Registrable Securities pursuant to this Agreement, on the date that such
    Registrable Securities are delivered to the underwriters for sale in
    connection with a registration pursuant to this Agreement: (i) an opinion,
    dated such date, of the counsel representing the Company for the purposes
    of such registration, in form and substance as is customarily given to
    underwriters in an underwritten public offering, addressed to the
    underwriters, if any, and to any Holder requesting registration of
    Registrable Securities; and (ii) a letter, dated such date, from the
    independent accountants of the Company, in form and substance as is
    customarily given by independent accountants to underwriters in an
    underwritten public offering, addressed to the underwriters, if any, and to
    any Holder requesting registration of Registrable Securities.

7.  INDEMNIFICATION.

    (a)  The Company will indemnify any Holder, each of its respective officers
    and directors and partners, and each person controlling such Holder within
    the meaning of Section 15 of the Act, with respect to which registration,
    qualification or compliance has been effected pursuant to this Agreement,
    and each underwriter, if any, and each person who controls any underwriter
    within the meaning of Section 15 of the Act, against all expenses, claims,
    losses, damages or liabilities (or actions in respect thereof), including
    any of the foregoing incurred in settlement of any litigation, commenced or
    threatened, arising out of or based on any untrue statement (or alleged
    untrue statement) of a material fact contained in any registration
    statement, prospectus,


                                     -10-

    offering circular or other document, or any amendment or supplement 
    thereto, incidental to any such registration, qualification or 
    compliance, or based on any omission (or alleged omission) to state 
    therein a material fact required to be stated therein or necessary to 
    make the statements therein, in light of the circumstances in which they 
    were made, not misleading, or any violation by the Company of any 
    federal, state, provincial or common law rule or regulation applicable 
    to the Company in connection with any such registration, qualification 
    or compliance, and the company will reimburse each such Holder, each of 
    their respective officers and directors, and each person controlling 
    such Holder, each such underwriter and each person who controls each 
    such underwriter, for any legal and any other expenses reasonably 
    incurred in connection with investigating, preparing or defending any 
    such claim, loss, damage, liability or action, provided that the Company 
    will not be liable in any such case to the extent that any such claim, 
    loss, damage, liability or expanse arises out of or is based on any 
    untrue statement or omission or alleged untrue statement or omission, 
    made in reliance upon and in conformity with written information 
    furnished to the Company by an instrument duly executed by such Holder, 
    controlling person or underwriter and stated to be specifically for use 
    therein.

    (b)  Each Holder will, if Registrable Securities held by such Holder are
    included in the securities as to which such registration, qualification or
    compliance is being effected, indemnify the Company, each of its directors
    and officers, each underwriter, if any, of the Company's securities covered
    by such a registration statement, each person who controls the Company or
    such underwriter within the meaning of Section 15 of the Act, and each
    other such Holder, each of its officers and directors and each person
    controlling such Holder within the meaning of Section 15 of the Act,
    against all claims, losses, damages and liabilities (or actions in respect
    thereof) arising out of or based on any untrue statement (or alleged untrue
    statement) of a material fact contained in any such registration statement,
    prospectus, offering circular or other document, or any omission (or
    alleged omission) to state therein a material fact required to be stated
    therein or necessary to make the statements therein not misleading, and
    will reimburse the Company, such Holders, such directors, officers,
    persons, underwriters or control persons for any legal or any other
    expenses reasonably incurred in connection with investigating or defending
    any such claim, loss, damage, liability or action, in each case to the
    extent, but only to the extent, that such untrue statement (or alleged
    untrue statement) or omission (or alleged omission) is made in such
    registration statement, prospectus, offering circular or other document


                                     -11-

    in reliance upon and in conformity with written information furnished to the
    Company by an instrument duly executed by such Holder and stated to be
    specifically for use therein.  Notwithstanding the foregoing, the liability
    of each Holder under this subsection (b) shall be limited in an amount
    equal to the public offering price of the shares sold by such Holder,
    unless such liability arises out of or is based on willful misconduct by
    such Holder.

    (c)  Each party entitled to indemnification under this Section 7 (the
    "Indemnified Party") shall give notice to the party required to provide
    indemnification (the "Indemnifying Party") promptly after such Indemnified
    Party has actual knowledge of any claim as to which indemnity may be
    sought, and shall permit the Indemnifying Party to assume the defense of
    any such claim or any litigation resulting therefrom, provided that counsel
    for the Indemnifying Party, who shall conduct the defense of such claim or
    litigation, shall be approved by the Indemnified Party (whose approval
    shall not unreasonably be withheld), and the Indemnified Party may
    participate in such defense at such party's expense, provided, however,
    that the Indemnifying Party shall bear the expense of independent counsel
    for the Indemnified Party if the Indemnified Party reasonably determines
    that representation of both parties by the same counsel would be
    inappropriate due to actual or potential conflicts of interest, and
    provided further that the failure of any Indemnified Party to give notice
    as provided herein shall not relieve the Indemnifying Party of its
    obligations under this Agreement unless the failure to give such notice is
    materially prejudicial to an Indemnifying Party's ability to defend such
    action and provided further, that the Indemnifying Party shall not assume
    the defense for matters as to which there is a conflict of interest or
    separate and different defenses.  No Indemnifying Party, in the defense of
    any such claim or litigation, shall, except with the consent of each
    Indemnified Party, consent to entry of any judgment or enter into any
    settlement which does not include as an unconditional term thereof the
    giving by the claimant or plaintiff to such Indemnified Party of a release
    from all liability in respect to such claim or litigation.

8.  INFORMATION BY HOLDER.  Any Holder of Registrable Securities included in 
any registration shall furnish to the Company such information regarding such 
Holder, the Registrable Securities held by him and the distribution proposed 
by such Holder as the Company may request in writing and as shall be required 
in connection with any registration, qualification or compliance referred to 
in this Agreement.


                                     -12-

9.  RULE 144 REPORTING.  With a view to making available the benefits of 
certain rules and regulations of the Commission which may at any time permit 
the sale of the Restricted Securities to the public without registration, 
after such time as a public market exists for the Common Stock of the 
Company, the Company agrees to Use its best efforts to:

    (a)  make and keep public information available, as those terms are
    understood and defined in Rule 144 under the Act, at all times after the
    effective date that the Company becomes subject to the reporting
    requirements of the Act or the SECURITIES EXCHANGE ACT of 1934, as amended.

    (b)  use its best efforts to file with the Commission in a timely manner
    all reports and other documents required of the Company under the Act and
    the SECURITIES EXCHANGE ACT of 1934, as amended (at any time after it has
    become subject to such reporting requirements);

    (c)  so long as any Holder owns any Restricted Securities, to furnish to
    any Holder forthwith upon request a written statement by the Company as to
    its compliance with the reporting requirements of said Rule 144 (at any
    time after 90 days after the effective date of the first registration
    statement filed by the Company for an offering of its securities to the
    general public), and of the Act and the SECURITIES EXCHANGE ACT of 1934 (at
    any time after it has become subject to such reporting requirements), a
    copy of the most recent annual or quarterly report of the Company, and such
    other reports and documents of the Company and other information in the
    possession of or reasonably obtainable by the Company as any Holder may
    reasonably request in availing itself of any rule or regulation of the
    Commission allowing a Holder to sell any such securities without
    registration.

10. TRANSFER OF REGISTRATION RIGHTS.  The rights to cause the Company to
register securities granted under Sections 2, 3 and 4 may be assigned to a
transferee or assignee in connection with any transfer or assignment of the
Warrants, the Conversion Right or Registrable Securities by a Holder, provided
that such transfer may otherwise be effected in accordance with applicable
securities laws and such transferee or assignee assumes in writing the
obligations of such Holder under this Agreement.

11. STANDOFF AGREEMENT.  Each Holder agrees, so long as such Holder holds
Registrable Securities that, upon request of the Company or the underwriters
managing any underwritten offering of the Company's securities, not to sell,
make any short sale of, loan, grant any option for the purchase of, or otherwise
dispose of any Apollo Common Shares (other than those included


                                     -13-

in the registration) without the prior written consent of the Company or such 
underwriters, as the case may be, for such period of time (not to exceed one 
hundred eighty (180) days) from the effective date of such registration as 
may be requested by the underwriters, provided that the officers and 
directors of the Company enter into similar agreements.

12. TERMINATION OF REGISTRATION RIGHTS.  All rights of the Holders under this
Agreement shall terminate 5 years from the completion date of the Company's
Initial Public Offering.

13. AMENDMENT OF REGISTRATION RIGHTS.  Any provision of the Agreement may be
amended and the observance thereof may be waived (either generally or in a
particular instance and either retroactively or prospectively), only with the
written consent of the Company and any Holders.  Any amendment or waiver
effected in accordance with this Section shall be binding upon each Holder of
any Registrable Securities then outstanding, each future holder of such
Registrable Securities, and the Company.

14. LIMITATIONS ON SUBSEQUENT REGISTRATION RIGHTS.  The Company shall not,
without the prior written consent of any Holder, enter into any agreement with
any holder or prospective holder of any securities of the Company which would
allow such holder or prospective holder to include such securities in any
registration filed under this Agreement, unless under the terms of such
agreement, such holder or prospective holder may include such securities in any
such registration only to the extent that the inclusion of his securities will
not reduce the amount of the Registrable Securities of any Holders which is
included 

15. ENTIRE AGREEMENT.  This Agreement constitutes the full and entire
understanding and agreement among the Parties with regard to the subject matter
hereof.  Nothing in this Agreement, express or implied, is intended to confer
upon any person or entity, other than the parties hereto and their respective
successors and assigns, any rights, remedies, obligations, or liabilities under
or by reason of this Agreement, except as expressly provided herein.

16. GOVERNING LAW.  This Agreement shall be governed by and interpreted and
enforced in accordance with the laws in force in the Commonwealth of
Massachusetts.  The Parties irrevocably submit to the non-exclusive jurisdiction
of the courts of the Commonwealth of Massachusetts with respect to any matter
arising hereunder or related thereto.


                                     -14-

17. SUCCESSORS AND ASSIGNS.  Except as otherwise expressly provided herein, the
provisions hereof shall inure to the benefit of, and be binding upon, the
successors, assigns, heirs, executors and administrators of the parties hereto.

18. NOTICES, ETC.  All notices and other communications required or permitted
hereunder shall be given or made in accordance with the provisions for notice
set out in Section 10.13 of the Royalty Agreement.

19. SEVERABILITY. Any invalidity, illegality or limitation in the
enforceability of the Agreement or any part thereof, by any Holder whether
arising by reason of the law of the respective Holder's domicile or otherwise,
shall in no way affect or impair the validity, legality or enforceability of
this Agreement with respect to any other Holder.  If any provision of this
Agreement shall be judicially determined to be invalid, illegal or
unenforceable, the validity, legality and enforceability of the remaining
provisions shall not in any way be affected or impaired thereby.

20. TITLES AND SUBTITLES.  The titles of the sections and subsections of this
Agreement are for convenience of reference only and are not to be considered in
construing this Agreement.

21  NUMBER AND GENDER.  In this Agreement, words in the singular include the
plural and vice versa and words in one gender include all genders.

22. COUNTERPARTS.  This Agreement may be executed in any number of
counterparts, each of which shall be an original, but all of which together
shall constitute one instrument.

23. DELAYS OR OMISSIONS.  It is agreed that no delay or omission to exercise
any right, power or remedy accruing to the Holders, upon any breach or default
of the Company under this Agreement, shall impair any such right, power or
remedy, nor shall be construed to be a waiver of any such breach or default, or
any acquiescence therein, or of any similar breach or default hereafter
occurring; nor shall any waiver of any single breach or default be deemed a
waiver of any other breach or default theretofore or thereafter occurring.  It
is further agreed that any Holder, permit, consent or approval of any kind or
character by a Holder of any breach or default under this Agreement, or any
waiver a Holder of any provisions or conditions of this Agreement must be in
writing and shall. be effective only to the extent specifically set forth in
writing and that all remedies, either under this agreement, or by law or
otherwise afforded to a Holder, shall be cumulative and not alternative.


                                     -15-

24. ATTORNEY FEES.  If any action at law or in equity is necessary to enforce
or interpret the terms of this Agreement, the prevailing party shall be entitled
to its reasonable attorney's fees, costs and necessary disbursements in addition
to any other relief to which such party may be entitled.


IN WITNESS WHEREOF, the Parties have caused this Agreement to be duly executed
and delivered by their proper and duly authorized officers as of the day and
year first written above.



                                   NEUROSCIENCE PARTNERS LIMITED
                                   PARTNERSHIP by its General Partner
                                   MDS ASSOCIES-NEUROSCIENCE INC.



                               Per:  /s/ Michael J. Callaghan, Vice-President
                                         _____________________________________
                                         Michael J. Callaghan, Vice-President

                               Per:  /s/ Keith Dorrington, Vice-President
                                         _____________________________________
                                         Keith Dorrington, Vice-President


                                   APOLLO GENETICS, INC.



                                   Per: ______________________________________