January 11, 1960

Dr. €3. George Mandel
Department of Pharmacology
I'he George -Washington University
School of Medicine
1339 H. Street
Washington. 5, D. C.

Dear George:

Thanks for writing and telling me about your interesting

experiments.
the pathway:

I can only guess at the interpretation but would favor

rhe question of ''turnoveri1 or' DNA or of DNA synthesis in

                     After all, when the cells

the absence of cell division can be debated but I'm inclined to feel
that it's safer to assume it can occur.
are presented with a variety of confusing environmental factors they
may try to initiate "growth'' even though some of the essential
factors eventually prove to be limiting.
experience with bromouracil incorporation (described in a recert
JBC) has some points of similarity to yours.

I imagine some of Zamenhof's

With best regards.

Arthur Kcrrzberg

es