Department of Genetics
University of Wisconsin
Madison 6, Wisconsin

April 18, 1952

Dear Dr. Spicer:

There are a few questions about your proposed fellowship visit
that ought to be cleared yp before fixing definite plans. First of
all, how long would you like to work here? You mentioned a period
of 3 - 6 months for the fellowship. Were you thinking of spending
most of that time here, or did you contexplate travelling a bit? An
interval of 4, perhaps 5, montha would be most likely to be productive.

As to starting time, it is a matter of probabilities. Some time
thie swmer or fall, depending on conetruction schedules in an another
building, we are due for some additional space. This itself would re-
quire some remodelling of our present facilities. It would be wmfor-
tunate if thie happened to coincide with your visit, and I mentioned
an advanced date so as to minimize thie possibility. If you are willing
to take your chances, you will be welcome if you can only conveniently
manage an earlier date. We could probably manage six square feet, but
ef course there's more to it than that.

With respect to possible proglems, there would be least likelihood
of collision with other work likely to be developed here,or by Zinder
at his new station after this spring, if we look for the recombination
system in other Salmonellas. I thought of 3. thompson because of the
variety of lysogenic forma worked out by Williame~Gmith. Can you obtain
access to a representative set? A similar group in typhimurium (after
Idlleengen) was quite invaluable. Your typhimurium x potsdam would he
quite interesting if it oan be extended to other markers. Our transduc-
tion system appears to be confined to the XIIz types, but we hardly know
enough yet to make any strict generalizations. Heve you any further de-
tails on this cross since your earlier letters on the subject? If they
would be of any help to you, we could probably provide some auxotropha
from S. typhimurium, or an 8 auxotroph for "SRP" testing for recombi-
nation. Or would you prefer to work them up yourself?

f

ure /sincerély, :
Jpetma Lederberg ow

Associaté Professor of Genetiog