exuyrne whore mtion was inreparably oonmcrted wlth tb maintenanoe of life ..* Thlr
ir oertainly aorreot if one oonaM.rr regregation data a8 tho only valid proof for the
existemu of geaea,  Emever a oueful aaralyrir of aurvival oru~W8 daring ergoaure to
~~10~8 lethal agsntr (ergo radiation, heat, ~OIOOEU, eta,) intitoate the exiatenm of
*iIr4bFftablo units' rho88 tnaotiration lead8 to deatb.  Ob0 might oonaoiwablp Macsgt
ruclhdata as rtrong imdicrationr for the erirteaoo of genes who80 abrenoe la lethal.
There are other mpeotr of this problem I hop to dlaanrr wlth you but in any ease a
quallfloation of the PbotQ atatemant might be safer although it ~g be admitted tbt
'safety' per ae la (B pretty nonotonow thing to atrive for.

With reierenoe to -8trrYea, I b I??-, but it 18 bprO8afOn that h~

war not rttinking of 'vttolly os8ential* ensJwnr when he ret np hla definition of the
ooxmitutinb enr;gfplb.
mnt and -8 f beliew,, reeking to empba8i~e differemes in rerponre to preaenae axxi
abaenae of aubrtrate.  He thua ended tap with a qualitatim raha&9 of oh8rifioetion
of enzyme8 altho it aee~ probable tlvrt thre d*ffetencre is fPrdarentally quatitatire
in nmare. Plsase bear in lalztd that I
have noted.

It sacma ti0 tly~ thiat la wao fa~turing hlr attention on the environ-

biased an thla eubjeot a8 you probably already

Thnnta again for your letOer and hares hoping we oan get t@getthbr som,