Exhibit
10.5


 



February
22, 2021


 


CM
Life Sciences II Inc.


c/o
Corvex Management LP


667
Madison Avenue


New
York, New York 10065


 


Re:Initial
Public Offering


 


Ladies
and Gentlemen:


 


This
letter (this “Letter Agreement”) is being delivered to you in accordance with the Underwriting Agreement
(the “Underwriting Agreement”) entered into by and between CM Life Sciences II Inc., a Delaware corporation
(the “Company”), and Jefferies LLC, as representative of the several underwriters (the “Underwriter”),
relating to an underwritten initial public offering (the “Public Offering”), of up to 27,600,000
of the Company’s units (including up to 3,600,000 units that may be purchased to cover over-allotments, if any) (the “Units”),
each comprised of one share of the Company’s Class A common stock, par value $0.0001 per share (the “Class A
Common Stock”), and one-fifth of one redeemable warrant. Each whole warrant (each, a “Public
Warrant”) entitles the holder thereof to purchase one share of Class A Common Stock at a price of $11.50 per share,
subject to adjustment as described in the Prospectus (as defined below). The Units will be sold in the Public Offering pursuant
to a registration statement on Form S-1 and prospectus (the “Prospectus”) filed by the Company with
the U.S. Securities and Exchange Commission (the “Commission”) and the Company has applied to have the
Units listed on the New York Stock Exchange. Certain capitalized terms used herein are defined in paragraph 11 hereof.


 


In
order to induce the Company and the Underwriter to enter into the Underwriting Agreement and to proceed with the Public Offering
and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, each of CMLS Holdings
II LLC, a Delaware limited liability company (the “Sponsor”), and the undersigned individuals or entities,
each of whom is a member of the Company’s board of directors and/or management team and/or an entity controlled by them
(each of the undersigned individuals or entities, an “Insider” and collectively, the “Insiders”),
hereby agrees with the Company as follows:


 


1. The
Sponsor and each Insider agrees that if the Company seeks stockholder approval of a proposed Business Combination, then in connection
with such proposed Business Combination, it, he or she shall (i) vote any shares of Common Stock (as defined below) owned by it,
him or her in favor of any proposed Business Combination and (ii) not redeem any shares of Common Stock owned by it, him or her
in connection with such stockholder approval. If the Company seeks to consummate a proposed Business Combination by engaging in
a tender offer, the Sponsor and each Insider agrees that it, he or she will not sell or tender any shares of Common Stock owned
by it, him or her in connection therewith.


 


2. The
Sponsor and each Insider hereby agrees that in the event that the Company fails to consummate a Business Combination within 24
months from the closing of the Public Offering, or such later period approved by the Company’s stockholders in accordance
with the Company’s amended and restated certificate of incorporation (as it may be amended from time to time, the “Charter”),
the Sponsor and each Insider shall take all reasonable steps to cause the Company to (i) cease all operations except for the
purpose of winding up, (ii) as promptly as reasonably possible but not more than ten business days thereafter, redeem 100% of
the shares of Class A Common Stock sold as part of the Units in the Public Offering (the “Offering Shares”),
at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account (as defined below),
including interest earned on the funds held in the Trust Account and not previously released to the Company to pay its taxes (less
up to $100,000 of interest to pay dissolution expenses), divided by the number of then outstanding Offering Shares, which redemption
will completely extinguish all Public Stockholders’ (as defined below) rights as stockholders (including the right to receive
further liquidating distributions, if any), and (iii) as promptly as reasonably possible following such redemption, subject to
the approval of the Company’s remaining stockholders and the Company’s board of directors, liquidate and dissolve,
subject in each case to the Company’s obligations under Delaware law to provide for claims of creditors and other requirements
of applicable law. The Sponsor and each Insider agrees to not propose any amendment to the Charter to modify the substance or
timing of the Company’s obligation to redeem 100% of the Offering Shares if the Company does not complete a Business Combination
within the required time period set forth in the Charter or with respect to any other material provisions relating to stockholders’
rights or pre-initial business combination activity, unless the Company provides its Public Stockholders with the opportunity
to redeem their Offering Shares upon approval of any such amendment at a per-share price, payable in cash, equal to the aggregate
amount then on deposit in the Trust Account, including interest earned on the funds held in the Trust Account and not previously
released to the Company to pay its taxes, divided by the number of then outstanding Offering Shares.


 






     


     


    

 


The
Sponsor and each Insider acknowledges that it, he or she has no right, title, interest or claim of any kind in or to any monies
held in the Trust Account or any other asset of the Company as a result of any liquidation of the Company with respect to the
Founder Shares held by it, him or her. The Sponsor and each Insider hereby further waives, with respect to any shares of Common
Stock held by it, him or her, if any, any redemption rights it, he or she may have in connection with (A) the consummation of
a Business Combination, including, without limitation, any such rights available in the context of a stockholder vote to approve
such Business Combination, or (B) a stockholder vote to approve an amendment to the Charter to modify the substance or timing
of the Company’s obligation to redeem 100% of the Offering Shares if the Company has not consummated a Business Combination
within the time period set forth in the Charter or with respect to any other material provisions relating to stockholders’
rights or pre-initial business combination activity or in the context of a tender offer made by the Company to purchase Offering
Shares (although the Sponsor, the Insiders and their respective affiliates shall be entitled to redemption and liquidation rights
with respect to any Offering Shares it or they hold if the Company fails to consummate a Business Combination within the time
period set forth in the Charter).


 


3. Notwithstanding
the provisions set forth in paragraphs in 7(a) and 7(b), during the period commencing on the effective date of the Underwriting
Agreement and ending 180 days after such date, the Sponsor and each Insider shall not, without the prior written consent of the
Underwriter, (i) sell, offer to sell, contract or agree to sell, hypothecate, pledge, grant any option to purchase or otherwise
dispose of or agree to dispose of, directly or indirectly, or establish or increase a put equivalent position or liquidate or
decrease a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange
Act”), and the rules and regulations of the Commission promulgated thereunder, with respect to, any Units,
shares of Class A Common Stock (including, but not limited to, Founder Shares), Warrants (as defined below) or any securities
convertible into, or exercisable, or exchangeable for, shares of Class A Common Stock owned by it, him or her, (ii) enter into
any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of
any Units, shares of Common Stock (including, but not limited to, Founder Shares), Warrants or any securities convertible into,
or exercisable, or exchangeable for, shares of Common Stock owned by it, him or her, whether any such transaction is to be settled
by delivery of such securities, in cash or otherwise, or (iii) publicly announce any intention to effect any transaction specified
in clause (i) or (ii); provided, however, all of the foregoing does not apply to the forfeiture of any Founder Shares pursuant
to their terms or any transfer of Founder Shares to any current or future independent director of the company (as long as such
current or future independent director transferee is subject to this Letter Agreement or executes an agreement substantially identical
to the terms of this Letter Agreement, as applicable to directors and officers at the time of such transfer; and as long as, to
the extent any Section 16 reporting obligation is triggered as a result of such transfer, any related Section 16 filing includes
a practical explanation as to the nature of the transfer). Each of the Insiders and the Sponsor acknowledges and agrees that,
prior to the effective date of any release or waiver, of the restrictions set forth in this paragraph 3 or paragraph 7 below,
the Company may announce the impending release or waiver by press release through a major news service at least two business days
before the effective date of the release or waiver. The provisions of this paragraph will not apply if the release or waiver is
effected solely to permit a transfer not for consideration and the transferee has agreed in writing to be bound by the same terms
described in this Letter Agreement to the extent and for the duration that such terms remain in effect at the time of the transfer.


 






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4. In
the event of the liquidation of the Trust Account upon the failure of the Company to consummate its initial Business Combination
within the time period set forth in the Charter, the Sponsor (the “Indemnitor”) agrees to indemnify
and hold harmless the Company against any and all loss, liability, claim, damage and expense whatsoever (including, but not limited
to, any and all legal or other expenses reasonably incurred in investigating, preparing or defending against any litigation, whether
pending or threatened) to which the Company may become subject as a result of any claim by (i) any third party for services rendered
(other than the independent registered public accounting firm) or products sold to the Company or (ii) any prospective target
business with which the Company has entered into a written letter of intent, confidentiality or other similar agreement or Business
Combination agreement (a “Target”); provided, however, that such indemnification of the Company
by the Indemnitor (x) shall apply only to the extent necessary to ensure that such claims by a third party for services rendered
(other than the independent registered public accounting firm) or products sold to the Company or a Target do not reduce the amount
of funds in the Trust Account to below the lesser of (i) $10.00 per Offering Share and (ii) the actual amount per Offering Share
held in the Trust Account as of the date of the liquidation of the Trust Account, if less than $10.00 per Offering Share is then
held in the Trust Account due to reductions in the value of the trust assets, less taxes payable, (y) shall not apply to any claims
by a third party or a Target which executed a waiver of any and all rights to the monies held in the Trust Account (whether or
not such waiver is enforceable) and (z) shall not apply to any claims under the Company’s indemnity of the Underwriter against
certain liabilities, including liabilities under the Securities Act of 1933, as amended. The Indemnitor shall have the right to
defend against any such claim with counsel of its choice reasonably satisfactory to the Company if, within 15 days following written
receipt of notice of the claim to the Indemnitor, the Indemnitor notifies the Company in writing that it shall undertake such
defense.


 


5. To
the extent that the Underwriter does not exercise its over-allotment option to purchase up to an additional 3,600,000 Units within
45 days from the date of the Prospectus (and as further described in the Prospectus), the Sponsor agrees to forfeit, at no cost,
a number of Founder Shares in the aggregate equal to 900,000 multiplied by a fraction, (i) the numerator of which is 3,600,000
minus the number of Units purchased by the Underwriter upon the exercise of their over-allotment option, and (ii) the denominator
of which is 3,600,000. The forfeiture will be adjusted to the extent that the over-allotment option is not exercised in full by
the Underwriter so that the Founder Shares will represent an aggregate of 20.0% of the Company’s issued and outstanding
shares of Class A Common Stock after the Public Offering (not including shares of Class A Common Stock underlying the Public Warrants
or Private Placement Warrants (as defined below)). The Sponsor further agrees that to the extent that the size of the Public Offering
is increased or decreased, the Company will purchase or sell Units or effect a stock dividend or share contribution back to capital,
as applicable, immediately prior to the consummation of the Public Offering in such amount as to maintain the number of Founder
Shares at 20.0% of its issued and outstanding Common Stock upon the consummation of the Public Offering. In connection with such
increase or decrease in the size of the Public Offering, (A) the references to 3,600,000 in the numerator and denominator of the
formula in the first sentence of this paragraph shall be changed to a number equal to 15% of the number of Offering Shares included
in the Units issued in the Public Offering and (B) the reference to 900,000 in the formula set forth in the first sentence of
this paragraph shall be adjusted to such number of Founder Shares that the Sponsor would have to surrender to the Company in order
for the number of Founder Shares to equal an aggregate of 20.0% of the Company’s issued and outstanding shares of Class
A Common Stock after the Public Offering (not including shares of Class A Common Stock underlying the Public Warrants or Private
Placement Warrants).


 






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6. The
Sponsor and each Insider hereby agrees and acknowledges that: (i) the Underwriter and the Company would be irreparably injured
in the event of a breach by such Sponsor or an Insider of its, his or her obligations under paragraphs 1, 2, 3, 4, 5, 7(a), 7(b)
and 9, as applicable, of this Letter Agreement (ii) monetary damages may not be an adequate remedy for such breach and (iii) the
non-breaching party shall be entitled to injunctive relief, in addition to any other remedy that such party may have in law or
in equity, in the event of such breach.


 


7. (a)
The Sponsor and each Insider agrees that it, he or she shall not Transfer (as defined below) any Founder Shares (or any shares
of Class A Common Stock issuable upon conversion thereof) until the earlier of (A) one year after the completion of the Company’s
initial Business Combination and (B) subsequent to the Business Combination, (x) if the closing price of the Class A Common Stock
equals or exceeds $12.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the
like) for any 20 trading days within any 30-trading day period commencing at least 150 days after the Company’s initial
Business Combination or (y) the date following the completion of the Company’s initial Business Combination on which the
Company completes a liquidation, merger, capital stock exchange, reorganization or other similar transaction that results in all
of the Company’s stockholders having the right to exchange their shares of Class A Common Stock for cash, securities or
other property (the “Founder Shares Lock-up Period”).


 


(b) The
Sponsor and each Insider agrees that it, he or she shall not Transfer any Private Placement Warrants (or any share of Class A
Common Stock issued or issuable upon the exercise of the Private Placement Warrants), until 30 days after the completion of a
Business Combination (the “Private Placement Warrants Lock-up Period”, together with the Founder Shares
Lock-up Period, the “Lock-up Periods”).


 


(c) Notwithstanding
the provisions set forth in paragraphs 7(a) and (b), Transfers of the Founder Shares, Private Placement Warrants and shares of
Class A Common Stock issued or issuable upon the exercise or conversion of the Private Placement Warrants or the Founder Shares
that are held by the Sponsor, any Insider or any of their permitted transferees (that have complied with this paragraph 7(c)),
are permitted (a) to the Company’s officers or directors, any affiliates or family members of any of the Company’s
officers or directors, any members or partners of the Sponsor or their affiliates (including members of the Sponsor’s members),
any affiliates of the Sponsor, or any employees of such affiliates; (b) in the case of an individual, by gift to a member of such
individual’s immediate family or to a trust, the beneficiary of which is a member of such individual’s immediate family,
an affiliate of such individual or to a charitable organization; (c) in the case of an individual, by virtue of laws of descent
and distribution upon death of such individual; (d) in the case of an individual, pursuant to a qualified domestic relations order;
(e) by private sales or transfers made in connection with any forward purchase agreement or similar arrangement or in connection
with the consummation of an initial Business Combination at prices no greater than the price at which the securities were originally
purchased; (f) by virtue of the laws of the State of Delaware or the Sponsor’s organizational documents upon liquidation
or dissolution of the Sponsor; (g) to the Company for no value for cancellation in connection with the consummation of an initial
Business Combination; (h) in the event of the Company’s liquidation prior to the consummation of an initial Business Combination;
or (i) in the event of the Company’s completion of a liquidation, merger, capital stock exchange or other similar transaction
which results in all of the Company’s stockholders having the right to exchange their shares of Class A Common Stock for
cash, securities or other property subsequent to the Company’s completion of an initial Business Combination; provided,
however, that in the case of clauses (a) through (f), these permitted transferees must enter into a written agreement with
the Company agreeing to be bound by the transfer restrictions herein and the other restrictions contained in this Agreement (including
provisions relating to voting, the Trust Account and liquidating distributions).


 






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8. The
Sponsor and each Insider represents and warrants that it, he or she has never been suspended or expelled from membership in any
securities or commodities exchange or association or had a securities or commodities license or registration denied, suspended
or revoked. Each Insider’s biographical information furnished to the Company (including any such information included in
the Prospectus) is true and accurate in all material respects and does not omit any material information with respect to such
Insider’s background. The Sponsor and each Insider represents and warrants that the questionnaire it, he or she furnished
to the Company is true and accurate in all material respects. The Sponsor and each Insider represents and warrants that: it, he
or she is not subject to or a respondent in any legal action for, any injunction, cease-and-desist order or order or stipulation
to desist or refrain from any act or practice relating to the offering of securities in any jurisdiction; it, he or she has never
been convicted of, or pleaded guilty to, any crime (i) involving fraud, (ii) relating to any financial transaction or handling
of funds of another person, or (iii) pertaining to any dealings in any securities and it, he or she is not currently a defendant
in any such criminal proceeding.


 


9. Except
as disclosed in the Prospectus, neither the Sponsor nor any officer, nor any affiliate of the Sponsor or any officer, nor any
director of the Company, shall receive from the Company any finder’s fee, reimbursement, consulting fee, non-cash payments,
monies in respect of any repayment of a loan or other compensation prior to, or in connection with any services rendered in order
to effectuate, the consummation of the Company’s initial Business Combination (regardless of the type of transaction that
it is), other than the following, none of which will be made from the proceeds held in the Trust Account prior to the completion
of the initial Business Combination: repayment of a loan and advances up to an aggregate of $300,000 made to the Company by the
Sponsor; reimbursement for any reasonable out-of-pocket expenses related to identifying, investigating, negotiating and completing
an initial Business Combination; and repayment of loans, if any, and on such terms as to be determined by the Company from time
to time, made by the Sponsor or an affiliate of the Sponsor or any of the Company’s officers or directors to finance transaction
costs in connection with an intended initial Business Combination, provided, that, if the Company does not consummate an initial
Business Combination, a portion of the working capital held outside the Trust Account may be used by the Company to repay such
loaned amounts so long as no proceeds from the Trust Account are used for such repayment. Up to $1,500,000 of such loans may be
convertible into warrants of the post-Business Combination entity at a price of $1.50 per warrant at the option of the lender.
Such warrants would be identical to the Private Placement Warrants, including as to exercise price, exercisability and exercise
period.


 


10. The
Sponsor and each Insider has full right and power, without violating any agreement to which it is bound (including, without limitation,
any non-competition or non-solicitation agreement with any employer or former employer), to enter into this Letter Agreement and,
as applicable, to serve as an officer and/or director on the board of directors of the Company and hereby consents to being named
in the Prospectus as an officer and/or director of the Company.


 


11. As
used herein, (i) “Business Combination” shall mean a merger, capital stock exchange, asset acquisition,
stock purchase, reorganization or similar business combination, involving the Company and one or more businesses; (ii) “Common
Stock” shall mean the Class A Common Stock and Class B common stock, par value $0.0001 per share, of the Company
(“Class B Common Stock”); (iii) “Founder Shares” shall mean the 6,900,000
shares of Class B Common Stock issued and outstanding immediately prior to the consummation of the Public Offering (up to 900,000
shares of which are subject to forfeiture by the Sponsor if the over-allotment option is not exercised by the Underwriter); (iv)
“Initial Stockholders” shall mean the Sponsor and any Insider that holds Founder Shares; (v) “Private
Placement Warrants” shall mean the 4,533,333 warrants (or 5,013,333 warrants if the over-allotment option is exercised
in full) that the Sponsor and certain Insiders have agreed to purchase for an aggregate purchase price of $6,800,000 (or $7,520,000
if the over-allotment option is exercised in full), or $1.50 per warrant, in a private placement that shall occur simultaneously
with the consummation of the Public Offering; (vi) “Public Stockholders” shall mean the holders of securities
issued in the Public Offering; (vii) “Trust Account” shall mean the trust fund into which a portion
of the net proceeds of the Public Offering and the sale of the Private Placement Warrants shall be deposited; (viii) “Transfer”
shall mean the (a) sale of, offer to sell, contract or agreement to sell, hypothecate, pledge, grant of any option to purchase
or otherwise dispose of or agreement to dispose of, directly or indirectly, or establishment or increase of a put equivalent position
or liquidation with respect to or decrease of a call equivalent position within the meaning of Section 16 of the Exchange Act,
and the rules and regulations of the Commission promulgated thereunder with respect to, any security, (b) entry into any swap
or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any security,
whether any such transaction is to be settled by delivery of such securities, in cash or otherwise, or (c) public announcement
of any intention to effect any transaction specified in clause (a) or (b); and (ix) “Warrants” shall
mean the Private Placement Warrants and Public Warrants.


 






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12. The
Company will maintain an insurance policy or policies providing directors’ and officers’ liability insurance, and
each of the Company’s directors and officers shall be covered by such policy or policies, in accordance with its or their
terms, to the maximum extent of the coverage available for any of the Company’s directors or officers.


 


13. This
Letter Agreement constitutes the entire agreement and understanding of the parties hereto in respect of the subject matter hereof
and supersedes all prior understandings, agreements, or representations by or among the parties hereto, written or oral, to the
extent they relate in any way to the subject matter hereof or the transactions contemplated hereby. This Letter Agreement may
not be changed, amended, modified or waived (other than to correct a typographical error) as to any particular provision, except
by a written instrument executed by all parties hereto.


 


14. No
party hereto may assign either this Letter Agreement or any of its rights, interests, or obligations hereunder without the prior
written consent of the other parties. Any purported assignment in violation of this paragraph shall be void and ineffectual and
shall not operate to transfer or assign any interest or title to the purported assignee. This Letter Agreement shall be binding
on the Sponsor and each Insider and their respective successors, heirs and assigns and permitted transferees.


 


15. Nothing
in this Letter Agreement shall be construed to confer upon, or give to, any person or corporation other than the parties hereto
any right, remedy or claim under or by reason of this Letter Agreement or of any covenant, condition, stipulation, promise or
agreement hereof. All covenants, conditions, stipulations, promises and agreements contained in this Letter Agreement shall be
for the sole and exclusive benefit of the parties hereto and their successors, heirs, personal representatives and assigns and
permitted transferees.


 


16. This
Letter Agreement may be executed in any number of original or facsimile counterparts and each of such counterparts shall for all
purposes be deemed to be an original, and all such counterparts shall together constitute but one and the same instrument.


 


17. This
Letter Agreement shall be deemed severable, and the invalidity or unenforceability of any term or provision hereof shall not affect
the validity or enforceability of this Letter Agreement or of any other term or provision hereof. Furthermore, in lieu of any
such invalid or unenforceable term or provision, the parties hereto intend that there shall be added as a part of this Letter
Agreement a provision as similar in terms to such invalid or unenforceable provision as may be possible and be valid and enforceable.


 


18. This
Letter Agreement shall be governed by and construed and enforced in accordance with the laws of the State of New York. The parties
hereto (i) all agree that any action, proceeding, claim or dispute arising out of, or relating in any way to, this Letter Agreement
shall be brought and enforced in the courts of New York City, in the State of New York, and irrevocably submit to such jurisdiction
and venue, which jurisdiction and venue shall be exclusive and (ii) waive any objection to such exclusive jurisdiction and venue
or that such courts represent an inconvenient forum.


 


19. Any
notice, consent or request to be given in connection with any of the terms or provisions of this Letter Agreement shall be in
writing and shall be sent by express mail or similar private courier service, by certified mail (return receipt requested), by
hand delivery or facsimile transmission.


 


20. This
Letter Agreement shall terminate on the earlier of (i) the expiration of the Lock-up Periods and (ii) the liquidation of the Company;
provided, however, that this Letter Agreement shall earlier terminate in the event that the Public Offering is not consummated
and closed by December 31, 2021; provided further that paragraph 4 of this Letter Agreement shall survive such liquidation.


 


[Signature
Page Follows]


 






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	 	Sincerely,
	 	 	 
	 	CMLS
    HOLDINGS II LLC
	 	 	 	 
	 	By:	/s/ Keith
    Meister
	 	 	Name: 	Keith Meister
	 	 	Title:	Manager
	 	 	 	 
	 	/s/ Eli
    Casdin 
	 	Name: Eli
    Casdin
	 	 	 
	 	/s/ Keith
    Meister
	 	Name: Keith
    Meister
	 	 	 
	 	/s/ Brian
    Emes
	 	Name: Brian
    Emes
	 	 	 
	 	/s/ Shaun
    Rodriguez
	 	Name: Shaun
    Rodriguez
	 	 	 
	 	/s/ Kevin
    Conroy
	 	Name: Kevin
    Conroy
	 	 	 
	 	/s/ Troy
    Cox
	 	Name: Troy
    Cox
	 	 	 
	 	/s/ Jason
    Kelly
	 	Name: Jason
    Kelly
	 	 	 
	 	/s/ Stephen
    Quake
	 	Name: Stephen Quake
	 	 	 
	 	CONROY
    FAMILY FOUNDATION, INC.
	 	 	 	 
	 	By:	/s/ Sheila
    Conroy
	 	 	Name:	Sheila Conroy
	 	 	Title:	President
	 	 	 
	 	THE
    KELLY FAMILY REVOCABLE LIVING TRUST DATED MARCH 31, 2015
	 	 	 	 
	 	By:	/s/ Jason
    Kelly
	 	 	Name: 	Jason Kelly
	 	 	Title:	Trustee


 






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	Acknowledged and Agreed:	 
	 	 
	CM LIFE SCIENCES II INC.	 
	 	 	 
	By:  	/s/ Brian Emes	 
	 	Name: Brian Emes	 
	 	Title: Chief Financial Officer and Secretary	 



 


 


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