January 16, 1951.

Dr. J. &. Gots,

Dert. of vBacterlology,
University of Pennsylvania,
Philsdelphia 4, Pa.

Dear Dr. Gota:

In reply to yours of the 9th, I an afraid that I hava only one or two
tryptcphanelseses mutants in K-12, on hand, beth of which have responded
to Indole, but whose general behavior has been rather drreproducible.

May I suggest that you comminicate with the following people, sach of
whom hes, I belfeve, picked up a few such mutants in K-12:

3.9. Davie 411%, 69 5t., New York,
Dan Harris Dept. Zoology, U. of Chicago
", L. Tatun Blology Stanford

nh, M. Bonner Eotany Yale.

Lam sorry to be unabls to be of greater assiatance,

Sincerely ycurs,

Joshua Lederberg,
Associate Professcr cf Genetics.