Auguat 8, 1952

Dr. 2. B. BE. mrray
Departmant of Bacteriology
University of Sestern Ontario
London, Ontario

Dear Dr. Murray:

Ve saw Bertani about tio weeks ago, when we heard his account of the
possibsy neterozygous Shigella. Tt seems a reasonable possibility that it
is diploid, although it may poasibly be diplogenic only for the proviral
"locus” itaslf. “a have now reasonably wall substantiated cases of both
occurrences in &. coll.

We are just now going over our slide material; I don't know whether
or aot T8211 be able to pick out a suitable set before I leuve for a vacation
a few duys henve, I do have soms photographs which are quite typical, and
enclose them for your bensfit. If these will not suffice, let ae know about
5 weeks from now, and I will try to do better. I hope such a delay will
nct embarrass you unduly.

Offhand, I should aay that if you can't easily tell the cultures apart
that this approach ought to be held in abeyance for more critical genetic
evicance. There ars a wumber of possibilities for verifying the diploid
hypothesis, based on the usa of recexsive sutations.

Froa your cytological observations, would you conclude that it is
likely that ladividual infested ceils beccne normal lysogsate without inter-
Galated call divisions? Scms cf our observations auggcst Uhat infected
ceils usually give contaminated clones, out of uwiich lysogenics arise only
iater. Such a pleture would of course suggest that the efficiency with which
sensitive celia can become converted to lysogenic is less than the prima
facie evidence would angseate.

Yours sincerely,

Joshua Hederberg