INST. FOR TUMORBIOLOGI |
KAROLINSKA INSTITUTET
STOCKITOLM 60

DEPT. OF TUMOR BIOLOGY

KAROLINSKA INSTITUTET Stockholm, April 27; 1961
STOCKHOLM 60

Professor Joshua Lederberg
Stanford University
Medical Center

Department of Genetics
Palo Alto, Calif,

USA

Dear Joshua:

Thank you very much for your letter of April 24, Many thanks also for
the advance honorarium which will solve all the problems regarding the deposit
for the house, etc. I hope that this is not too much trouble for you. We have
now made arrangements to arrive on June 10, I shall let you know the exact
time of our arrival as soon as I get the reservations confirmed,

Eva thinks that experiments regarding the transfer of genetic information
in B, gubtilis by DNA sound very exciting. Have you seen the recent letter
of Ephrussi regarding fusion in somatic cells? It shows fusion very clearly,
with help of chromosome markers, and it does not seem to be a very rare occur-
rence at all. On the other hand, the cells fused are all tetraploid and in his
paper there is no evidence for segregation. Should there be segregation as a
regular event, we ought to have seen it in the experiments on mixing two F
tumors, A lot could be done with fused cells without segregation also, at least
as far as questions of dominance and gene expression are concerned. The "somatic
crossing over" project which I mentioned in Bar Harbor is going on at full
speed and so far we have not obtained anything that would contradict or exclude

this mechanism. Much more remains to be done, however, before we can be sure
of it.

We are getting closer to the day of the departure and, although things
get more and more hectic all the time, we are looking with great expectation
and, indeed, relief (that is, relief from the telephone, from visitors, from
the new building, from committees, etc.) to our trip.

With warmest greetings, also to Esther,

Yours as ever,

— .

George Klein

GK/AL