October 19, 1953

Dr. G. H. Bergold
Laboratory of Ineect Pathology
Sault Ste. Marie, Ont., Canada

Dear Dr, Bergold:

Thank you for your cordial message of the 15th. It obviously would be
impossible to investigate the mode of transmission of insect viruses until
one can be confident of securing virus-free lines, but the very prevalence
of the virus would be strong circumstantial evidence of an endosymbicsis.
However, I have in mind the work of Fukushi and Black on the assimilation
of plaht viruses to insects. I have in question now not so mch the persis~
tent heredity of the viruses in the insect, but rather the diet as a possible
recurrent source of virus agents. Are the insects commonly used as subjects

of virus research amanable to culture under stepile ({1.e. axenic) conditiong?
excluding even plant cells?

I appreciate your suggestion of a visit to your laboratory, and will
keep it in mind for any future opportune cesasion. In fact, last summer
(August 1952) we vacationed in Ontarlo,agietiec and the Maritimes, and drove
right past your laboratory. It was a rather depressing rainy afternoon, and
I am sorry that it ddd not occur to either of us at the time tc visit it.

Yours sincerely,

Joshua Lederberg

P.S. By all means, may I reciprocate your invitation. Wa are not often
anay from Madison except occasional summers.