CARNEGIE INSTITUTION OF WASHINGTON
DEPARTMENT OF GENETICS

COLD SPRING HARBOR, LONG ISLAND, N. Y.

viay 2, 1946

Mr. Joshua Lederberg

Osborn Botanical Taboratory
Yale University

New Haven, Conn.

Dear Mr. Lederberg:

In your letter of avril 29th, you
requested information on stocks of Neurosvora crassa
that give good results with the aceto-orcein stain.

The best staining I obtained, and it was excentionally
good, followed from the cross of Em 5256A x Chilton a.
“ow these staining qualities would behave in various
other erosses of tnese strains is still unknown, Your
suggestion of carrying on good cytological material slong
with snecial genetic material is well taken. Mowever,

we know nothing about the segreeation factors involved.
it} would be easy to follow this. «2 quick test of stain-
ing is all that is necessary to determine the quality of
the staining. It aovears almost immediately.

The reprint that you reouested has been
sent.

Sincerely yours,

(Lubes Weclubey

jarbara MeClintock