December 16, 1955

Mr. Donald M. Green
Biviogy
University of Rochester, N.Y.

Dear Mr. Grean:

I am sorry but I do not have any of the chloramphenisol resistant
cultures of ©. coli K-12 at Madison. I am sure that Pr. Cavalli will
be happy to send them to you, but I suggest that you give him a more
explicit outline of what you intend to do, so that hs can make thea
better choice among his material for you. You can write to Or. Cavalli
at the "Istituto Sieroterapico Milanese, Via Darwin 20, Malan, Italy".

I hope you will be more successful at obtaining a DNA-transiuction
with K-12 than Atchley was (see CSH, 16:441). There is certainly no
reason in principle why this can't be done. Or. Doasrec has recently
been claiming such a transduction in Salmonella: perhaps his methods
would be of some use to you. If it dows come out, T hope you will let
me know.

My best ragardsa for ths season to Or. Ravin,

Yours sincsreiy,

Joshua Lederberg
Professor of Genetics