Novanber 2151924?-

Dr. Wikhon 5, Stone,
Dept. of Zoology,
University of Texas,
Austin, 12, Texasé

Dear Dr, Stone

In response to your request, I have sent E. coli K-12 under
separate cover.

Will nothing else do for Y~24? I have not maintained this
culture at Wisconsin, because I had no speoial need for it and
it wae a nuisance adding extra cystine to stock agar slants. If
you have to have it, you may be able to get it either from Bonner
at Yale,or Tatum at Stanford. It was very likely lyophilized.

. Yours sincerely,

Joshua Lederberg
Aasistant Professor of Genetics