May 22, 1951.

Dear Kin-

You ean probably best anawer this in person at CSH; if I had finished
my s., T'd be hanpler about the trip-—- I1'21 bet you're in the same bost.

Have you considered this possibility?-

Accept that the initial h- and he arising from it ere selectively equivakent
in your medium, and that the initial rise of h+ is cheoked by non-sepecific
PS, Suppose, however, that there were adaptations which were only or more
effective in h- than h+ timupckam; and the converse. The result would be
that predcminantly le populations woud fix modifiers that select against h+,
and wice versa. The ultimate equilibrina would, then, be one cf mation as
againat selectiicn, although your initial cultures do not necessarily start
out that way. This can be checked, of course, by comparing h+ from terminal
he, ageinet that i, with the luitial pairs. It#would account for the con-
tinuation of an squilibriua. Do your fully adapted cultures cn synthetic
medium grow as rapidly as their counterparts on complete? that would seem
to fix some sort of lhait oa tue potentiality for adaptation.

Thanks for the information on Woods Hole. Right now it lAoks as if we may
est up thera for a fow days, but don't want to be tied down to a definite
conmal tment.

We@ll see all of you scon-

\ Sinserely,
i t

i
fe

Joshua Lederberg