February 12, 1952

Dr. P. R. Edwards
Comminicable Diseases Ctr.
Box 185, Chamblee, Ga.

Dear Dr, Edwards:

Thank you for so phogmtly returhing our manuscript on Salmonella
genetic tranaductions. We are waiting only for a few more electrok micro-
graphs of some more highly purified "FA" (activity re prototrophs, several
million unite per ml) to submit the paper to the Journal of Bacteriology.
We are also making amendations in response to your suggestions.

You did catch us on the regularity of occurrence of the flagellar
transductions! Mhile you had the paper, we did some more oxner{mente.
In about 20 incoulations, about 10 were motile against anti-d. One or
two were j-phases; the rest were 1;-—-~-. Stramgely enough, no -—-1,2,3...
traneductions have been observed yet, utkkwexwk using PA from either a
diphasie or a phase-2-monophasic 8. typhimurium, The 1 phase has not,
of course, appeared from typhi without FA. The experiment should not be
difficult to reproduce; we would be pleased to send you some active
material from typhimrium if you had any special interest in it.

Ag to the fermentetive changes, xo evidently did not make x& sufficiently
clear what we were doing. Because we did most of this work within 3.
typhiaurlum, we relied on non-fermenta&ing mutants obtained in the labo-
ratory. The transduced changes are, indeed, back tc the nopmal wild-type
condition, As such, they are not in any sense novelties. However, the
rate at which such back-autations! occur is a useful test for the genetic
properties of the ective preparations. In some stoeks, back~-mutations
ocourred spontaneously, but this was carefully taken into account in
evaluating the "FA" results. The only novelties were in the stypén "crosses",

We have been interested in the monotonous cecurrence of 1;-- types,
and wonder if we could not now transduce 1,2,3... in a second step. For
this we need a new supply of specific sera, Your 1942 pamphlet recom
mends S. bonaeriensis phase 1 and 3. newport v. puerto-rico. If we could
have these cultures, and the S. typhimurium 0-ferm,(#13) we would again
be most grateful.

Yours sincerely,

Joshua Lederberg

P.S. A dissecting microscope makes a fairly effective microfilm-reader.