Department of Genetics
University of Wisconsin
Madison 6 Wis.

Septenber 17, 1952

Dear Dr. Hirsch:

Dr. Be Ae Ds Stocker (of the London Behool of Hygiene) and I
have recently been collaborating in a study of nonmotile vardante
in Selmonella, and have thus been directed to your 1°47 paper on
this subject which appeared in the Journal of Hygiene.

IT am writing to ask whther the very Interesting cultures of
Se paratypnl B described in this paper have been preserved, and
whether you would be kind enough to make them abailable to us for
further genetic study. If possible, we would appreciate having the
presurebly original H form, as well as the psralyzed mutente In addi-
tion we are looking for reasonably stable © variants, of this same or
any other oripin.

We nave been working on nen-Plagellated and paralysed mutants
of 3. typhimurium for the moct part (the letter provided by BE. Leifson
of tha Ohicago). There is very little doubt that your suggestion is
correct that the paralyeed mutante represent a genetic change quite
distinct from the O varierts. The cxperimental details are too com-
plex to sumsarize briefly here, but will be forwarded to you as a
reprint in due course.

If Toomey nate o further requeet, may I have « reprint of the
above mentioned paper?

Yours sincerely,

Joshua Lederberg
Acscciate Professor of Gonetdes

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