November 21, 1950.

Dr. P. Frederica,
Institute of Bacteriology,
University of Liege,
Liege, Belgiua.

Dear Dr. Fredericq:

I have your letter of November 15, asking for a note in support
of your candidacy for the directorship of your institute. I should
be pleased to support you in this position, to the extent that the
obvious limitations permit. I hope that the enclosed letter will suit
your needs.

My second letter mst have crossed yours in the mails. In it, I asked
whether you would be kind enough to send me 17 E. coli cultures represen-
ting the different colicin types, as well as a single sensitive, to each
of them. My work with strain crosses now emphasizes the importance of
colicin-producers aga well as colicin-seasitives, so that I would like
to ask an extended favor. I can only readily correlate the types of
colicin-prdducers with yours by comparisons with resistant strains.

I could obtain these myself as mutants by selecting with the different
colicin producers, but it would save considerable effort if you could
send me the different resistant strains with which you type the colicins.
This is now quite a large request: at least 35 cultures. If you would
prefer to ship these cultures by air express, rather than by mail, I will
be ghhd to assuge the charges (i.e., C.0.D. or collect on delivery).

Thank you for your troubles,
Sincerely,

Joshua Lederberg,
Associate Professor of Genetics