Fun ue Bekele,

Dr. O. He Browning,
July 31, 1950.

Professor C. H. Browning,
Department ofvBacterLology,
University of Glasgow,
Scotland.

Dear Professor Browning:

Thank you for your kind note of Jume 12. I was very pleased that
you called my attention to your 1908 paper citing your experiment wth
mixed trypanosome infections. As far as I know, this fe clearly the earliest
anticipation of the selective methods for the detection of microbial
recombinants. May I interpret your statement "Inoculationa with mixtures
of two resistant strains show that the two varieties, although derived from
the same stock originally, behave as if they were distinct species" to
mean that this experiment was actually designed to test for the occurrence
of character reoombination?

I shall be very glad indeed to send you reprints of this work, as
soon as I can. It 1s probably too mich to ask, but if you should hapven
to have preserved an extra reprint of thie 1908 paper, I would enjoy re-
ceiving it. Too, if you happen to recall any other contemporary published
work of this sort, I would appreciate your telling me of it.

For some time, I have been intrigued (in a literary way only, so far)
by the problem of the mechanism of induction of aparabasal drug-resistant
mutants of trypanosomes. The literature seems to be somewhat indecisive as
to whether the drugs aet purely as selective agents, or whether they may indeed
directly induce the loss or modification of the parabasal body. The genetic
significance of this possibility should be apparent. Any eco-nent you may have,
or suggestion as to the posaibility of in vitro studies to verify this point,
would be appreciated.

Youra respectfully,

Joshua Lederberg,

 

Vieiting, Surmer Session.

Associate Professor of Genetics
UNIVERSITY OF WISCONSIN

)- PA, Bec

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