duly 30, 1952

Dr. Norton D. Zinder
Roakefeller Institate for Medical Research
New York 21, N.Y.

Dear Norton:

Qebhdy proof for Genetic Exchange in Salmonella came in today. There did
not seem to be auch point in forwarding it to you, eftpecializ as I did not
know whether you were easily accessible or not, so I took care of it. Your
new address was added to the footnote. You made a couple of boners, especially
in the bibliography, but the editor caught theg, The figures cage out beautifully.
The text reads about the same as over. [I should have myself!)

600 reprints were ordered ($35), with inetructdons to ship 200 to you. Let
me know 4f this arrangement is unsatisfactory. You should have received 25
reprints of the C&H '51 paper, plus a couple specifically for Rockefeller people.
We have a fairly coafortable supply of these, but no surfeit.

Stocker has been giving us, and I hope himself, a good time. Most of the
O forme in warious spp. are non-allelic, at least they trana@uce each other.
He has pioked up a very interesting effect: tracks of nicrocolonies which only
occasionally end in a swarm. They aay be temporary fomam or very unstable trans-
ductions. Most swarms begin {in such tracks (possible segregation of O- from transduced
OH- nuclei). The Gel- transduction in B, solt looks very substantial, and very
likely due to lambda. Wo other loci ae yet. Many of the transductions are undtable
and give rather than Gal+ papillae, anlike spontaneous papillae which are
all Gal+{ weather has been aostly awfully hot; there have been innumerable
mss., proofs, etc. Ethelyn has picked several cells that later turned out to be
aygotes. They are not especially distinctive, and we have no knowledge of their
previous ickuws history in the mixed cultures, but I still suspect temporary pairings.

Sincerely,

Joshua Lederberg

i

4 : —

P.S. Your diligence in notifying correspondents has gaved us from having to
forward any appreciable amount of mail. But anyhow,{ may I have your explicit
permission to use ay judgement in throwing out 34 class junk?

dL