april 12, 1949.

Dr. A. H. Doerrmann,
Carnegie Inst.,

Cold Spring Harbor, L.I., N.Y.

Dear Gus:

If you still have one handy, I wonder if you could send me a copy
of the Phage Information Service in which you detailed your work on
the enumeration of intracellular phage. E. coli K-12 turns out to
be lysogenic, and I think that I'd like to try to count the number
of phage particles that it's carrying per cell. I've been trying to
use radiation, a la Preer, but with very sporadio success so far.

Just to antisipate a question, lysogenicity has nothing to do
with recombination, although the latent virus does condition resistance
(by Interference?} to u f6-phage isolated from sewage for just this
characteristic. |

Thanks for your assistance.

If there's tims, I'll try to visit the labs the week of May 30
when I may be East.
Sincerely,

Joshua Lederberg