Jamaary 17, 1952

Dear Brucet

Your friendly letter somewhat mitigated my disappointment at
your indispensability to higher learning in Britain. I had no right
to expect that you would be able to extend your visit, as Esther had
told me you had discussed yourpplans with her. A shorter visit would
be second best, and we approve heartily of the principle.

Ne have indeed worked full steam during the summers (except 1950
when I taught at Berkeley). Unfortunately, steam ie almost too apt a
description of the atmosphere, and we had more or less wanted to go
aomerhere else (anywhere would do) for part of this summer. However,
our plans are by no means fixed, snd my own ucedemic responsibilities
will be rather fiexible, sc that it mey still be possible to work
something out to our mutual advantage. Since the demands on you form
somewhat of a fulcrum for any discussion, it might. be simplest if
you could first indicate your probable range cf action in time, from
which we could then try to work out the beat arrsngement. I was not
entirely clear just when you could leave NYU, and the latest you had
to be back in London. Three months would be 2hout one-fourth as valuable
28 a year, and should he barely Long enough to start snd begin to
finish something. I am delighted et the prospects of a resuscitation
of H-phages: perhaps we could find something to do with them together.
I am locking forwsrd tosseeing what they ranlly are

Since I wrote you, I've managed to shake off some of the incubus
of ~riting, and em working on a very curious self—sterility situation
in K-12. Esther had pikked it up somo time ago, and a letter from
Cavalli brought it again to my attention. It boils down to the fact
that some strains are F-, most are Fs, the symbols being defineble by
the condition that F~ x F- is completely sterile, whereas F+ x F-~ and
F+ x F+ are fully fertile, The inheritance of F was very peculiar, all
sexual progeny being F+. Some experiments where a cixtcre of F+ and Be
was used as "one" parent (nutritionally speaking) x F~ led me to think
for a while that an "P+ Bormone" was involved, but it turns out that
the activation of F- growth with F+ {in one experiment) was permanent,
so that it looks $fAke there 1s extracellular transmission of the F+ factor,
almost cer not via lambda. Filtrates of F+ cultures have.not so
far diplayed any modification of F-, so that the experiments so far are

not entirely satisfydng. Ig this sounds confusing, don't blame yourself.
Sincerely,

Joshua Lederberg