CARNEGIE INSTITUTION OF WASHINGTON

DEPARTMENT OF GENETICS

COLD SPRING HARBOR, LONG ISLAND, N. Y.

February 14, 1950

DR. Joshua Lederberg
Department of Genetics
University of Wisconsin
Madison, Wisconsin

Dear Joshua,

I think the following compounds, in addition to methyl
green, will suit your mysterious purposes: basic fuchsin,
mereuric chloride, silver nitrate, sodium hydroxide and sulfuric
acid, These are all highly toxic, and clearly nonmutaegenic
within the limits of the phege and streptomycin methods of
detection. There are lots of others that are nonmutagenic but
not very toxic -- I assime you don't care about these,

I’m anxious to get your note -- my curiosity is roused,

Best regards to Esther --

Sincerely,

Evelyn Witkin