Columbia Gnibersity
College of Physicians and Surgeons

630 WEST 168TH STREET
NEW YORK 32, N. Y.

DEPARTMENT OF BIOCHEMISTRY

CELL CHEMISTRY LABORATORY January 35 1958 OFFICE: ROOM 12-201
TEL. WADSWORTH 3-2500
EXT. 7479

Dr. Joshua Lederberg
Genetics Building
The University of Wisconsin
Madison 6, Wisc.
Bear Joshuas

Being the benign old professor type I love to correspond with my
former students if they write nice letters. Our interpretation may of
course have been incorrect, though I hope not; but I do not believe our
observations were. If your explanation of a selection process having
occurred were right, I should have expected that we should have had more
than the rare successes we recorded. We are, however, continuing along
different lines; it is slow worke I was sorry to hear that you had been

unsuccessful in similar experiments.

pir

Erwin Chargaff: eb