Septegber 22, 1952

Dear Topsy:

We had the same experience with the serineless. I think it may
actually do best on serine+glyctne, but we have never been especially
interested in their chemistry. From what I can recall hearing from
other people this experience is pretty general. The sam mutants sean
to do quite well on complete medium; perhaps there is a nondescript
requirement for other metabolites (perhaps as a result of inhibition
by accumulated intermediates).

I would like very mich to have reprints from Joe and yourself.
I think the mat recent I now have were the work with ELT.

\ Sincer ely ’
j “ : er

. Joshua Lederberg

Dr. S. Simonds

Dept. Physiological Chemistry
Yale University School of Medicine
New Hagen, Conn.