Columbia Aniversity
College of Physicians and Surgeons

630 WEST 168TH STREET

NEW YORK 32,N.Y.

DEPARTMENT OF SURGERY
SURGICAL PATHOLOGY

August 20, 1946

Dear Josh;

With my head boweé in shame I write you that the
coli mutants would not grow in transplants (3 attempts) .
Could you send me duplicates of all three since I am rather
anxious to determine their usefulness in assay.

As far as biosynthesis is concerned, I will certainly
consult you well in advance. I think it will be useful, however,
at this time to determine the organism's efficiency in utilization
of nitrogen; how much of the medium N goes into nucleic acid,
Roukhly 10% of the neurospora N is nucleic acid N, but even there
I haven't determined the efficiency of utilization. I may then
grow a small culture for analysis; I should expect that from the
E. Coli will get about thirty to fourty percent nucleic acid,
certainly more profitable than neurospora for us.

We are having variable results in our isolation of
nucleic acid from neurospora; we don't have the last word there yet.
E, Coli will present adifferent picture, but I wonder if we'll get a=

more desoxyribo out of it.

Sincerely,
amuel Graff,