From pea Rrotiosen SW Ae Sse, THE WRIGHT-FLEMING INSTITUTE OF MICROBIOLOGY,
ST. MARY'S HOSPITAL MEDICAL SCHOOL.
PADDINGTON. LONDON. W.2.

15th July 1953.

TELEPHONE PADoincTon 1148

Dear Dr. Lederberg,

You may be aware that we have been amusing ourselves
by dabbling in bacterial genetics lately. In particular
we have been analysing the possible linkage of valine and
mnorleucine inhibition of Kl2 strains, with other factors,
We find that valine inhibition is closely linked with
leucine independence and morleucine inhibiton€islinked to
galactose fermentation as shown on EMB plates.

This is not my main reason for writing at the moment
however, Bruce Storker suggested nat you might be kind
enough to send me subcultures of (all. your EH. coli strains
which mate with K12. I am doing some work on the virulence

to mice of E, coli strains and your cultures might well be
of great help to me,

Are you coming over to Europe for either of the
Congresses in Italy in September? If so I would welcome
the opportunity of meeting you.

Yours sincerely,
~

wel ee payee oe

Dr. Derrick Rowley,

Dr. J. Lederberg,
Department of Genetics,
University of Wisconsin,
Maddison,

Wisconsin, U.S.A.