April 9, 1946+

Dr+ LJ. Wickerhan,

NRRL; Peoria Ill,

Dear Sir:

Excuse me for writing you twice on the same subject, but in the process of

moving here from Columbia, your last letter to me was packed away in a plage
not now accessible, I am working here now with E+L.Tatum on the genetics of
some microorganisms, and we have definitely decided to take a crack at studying
mutations (if we can induce them) in your Schizosaccharomyces versatilis (W+D)
of which you already sent me culture some time ago.

The only important point whic} I cannot quite recall is the simplest medium
(synthetic) on which they will grow, if there is any. I h&pe you will correct
me if I am wrong in the assumption that the Sehtzosacch. are haploid in the
vegetative phase (like Neurospora) and conjugate just before sporulation, and
that the ascospores are presumed haploid. I do not mean to d:mand critical
evidence (which we hope tc fini) but is that the assumed picture? Also pre-
sumably the organism is homothallie «nd single spore cultures can sporulate?
Trust that we shall keep you informed of eny important developents. If you
know of any heterothallic yeasts with a life cycle Uke Neurospora,we should
of course be very grateful to hear about it. I suppose that question has been
put to you before.

Sincerely yours,

Joshua Lederberg.