CHEMICAL CORPS BIOLOGICAL LABORATORIES
MEDICAL BACTERIOLOGY DIVISION

Gomp Detrick, Frederick, Maryland

3 July 1953

Dr. Joshua Lederberg
Dept. of Genetics
University of Wisconsin
Madison 6, Wisconsin

Dear Josh:

I have an extra copy of the MS which Hayes presented at the
Cold Spring Harbor meeting. In case you did not get a copy of this
MS directly from Hayes, I shall be glad to send you my extra copy.

Incidentally, there are some differences in residual growth be-
tween F+ and F- strains, but more work has to be done in order to
determine whether these differences are in any way correlated with
recombination frequencies. The present difficulties arise from the
fact that the observed differences in residual growth shift signifi-
cantly with the siZe of the inoculum employed.

With best regards,

Very sincerely yours,

Les

WERNER BRAUN
WB/bls