November 13, 1950.
Dear Ed:
I was a little surprised at the note in the last J. Bact. on use of tetrazolium for differentiating R & S "your bug"--why so coy about naming it in your letter?  It would almost imply some difference either in general rH level between R and S, or else some specific metabolic difference in dehydrogenation of some substrate in your medium.  Are you making similar comparisons with other species?
I doubt that I have any mimeograph material for class use that you don't already have.  UW Press has approved a republication of a selected set of reprints (Luria and Delbruck; etc.) for teaching use; they should be out by next Fall.  The current Methods in Medical Research (Vol. 3), just out, has a section on methods in microbial genetics.  There are rumors of a text, in press, in England.
What, exactly, do you mean that a stored suspension goes avirulent?  Is this a propagated change, or is it simply a matter of the immediate physiological conditon of the cells at the time they are inoculated.
How about those gigas forms?
Camphor had no effect on E. coli.  I'd tried this in 1947, but thought I could do better now, but no luck.
Sincerely,
Joshua Lederberg