CARNEGIE INSTITUTION OF WASHINGTON

DEPARTMENT OF GENETICS

COLD SPRING HARBOR. LONG ISLAND, N. Y.

January 11, 1955

Professor Joshua Lederberg
Department of Genetics

The University of Wisconsin
Madison 6, Wisconsin

Dear Joshua:

We are sending you today a batch of about 30 vials with lysates
of various mutants. Another shipment will be made within the next few
days, as soon as we receive a new supply of small vials.

I assume that the symbols we use are not different from yours,
and that you won't have any trouble in identifying the material. How-
ever, I will just outline in a few words our procedure, A mutant is
given a name according to the effect it shows: for example, proline,
histidine, cystine, and so on, As a symbol we use the abbreviation of
the name. Similar mutants of independent origin receive numbers, in
the order in which they were found, Finally, a capital letter is
assigned after the mutant has been placed in a group (after the locus
has been determined), Thus the complete symbols for some cystineless
mutants are as follows: cysA-1, cysA-20, cysB-10, cysB-15, cysC-7,
cysC-36, etc.

With best regards,

Sincerely yours,

JA. prerieree, of

MD:af M. Demerec