Department of Genetics
University of Wisconsin
Madison 6, Wis.

*

July 9, 1951

Dear Dr. Inoki:

I have your letter of May 25. I regret not having replied sooner
but could not owing to a business trip.

T am very vleaged to hear of your work on trypanoglsome
variation. Many of us have long suspected that the cyclical changes
found in infected animals might have a bsis similar to the changes
in Paramecium, but of course the possibility of natural selection
of spontaneous changes has had to be ruled out. I shall look forward
to reading the details of your work.

You mention that fission is not required for the development of
serological changes. Does this mean that a limited time of treatment
with antiserum suffices, or more strictly that the changes can actually
be detected in the sane treated individuals. Several examples have
been found where a limited exposure of cella te an external agent
resulted in influences which persisted several generations, owing to
adsorbed agent; metabolic alterations, etc., ~-therefore this question.

Heve vou considered another similar problem with trypanosomes:
the mechanism cf formation of aparabasal forms under the influence of
acridine dyes? The published work suggests strongly that this is a
diructed effect aleg, and not selection of spontaneous mitants, but
the work that has been done has not really been adequate to settle
the point, Since, in this case, the "plasmagene" is a visible particle,
it might afford considerable edvantages in the analysis of these
directed effects. I have hoped to find a student who would be interested
to work on this problem, but the cecasion has not yet arisem, and is
rather unlikely to for some time.

Under separate cover, I am sending whatever reprints are still
in supply, and I will be heppy to add your name me to our mailing list
for exchanges from time to time.

Yours sincerely,

Joshua Lederberg,
Associate Professor of Genetics