MEDICAL RESEARCH COUNCIL

Telegrams .- ' NATINMED, MILL, LONDON.'

NATIONAL. INSTITUTE FOR MEDICAL RESEARCH,

Telephone : MILL HILL 3666. THB RIDGEWAY, MILL HILL,

LONDON, N.W.7.

11th September, 1951.

Dr. S. Spiegelman,
Depts. af? Bacteriology 62 Physiology,
University of Illinois,
Urbana, Ill., U.S.A.

Dear Spiegelman,

"hank you very much for your letter and reprints,  and also

for the manuscript of your recent paper which I have only just
read, having been away on holiday.  I am very grateful to you
for letting me see this manuscript which I found most interesting
and stimulating.

There is just one question I would like to put to you;

have you tested the effect of galactose conwfzjn the rate
of reversion of cellse subsequent to growth
galactose?  U so, what effect did you find, i.e., did it dfect
the speed of reversion or the proportion of positive colonies
appearing after the point when mass reversion occurred in galactose

concentration of

It seems to me that this might have an important
peptone and yeast extract! is really completely

possible interpretation of your phenomena;
re you satisf'ied that your

          and,
alactose-free medium

ose?

It seems to me that this might conceivably

on the production of the small quantity of
which you ascribe to genetic factors.

    I wonder if you would mind my holding on to your manuscript
for a week or two longer and whether you have any objection to my
showing it to one or two colleagues wha  are also interested in the
subject:
year .

I suspect we  may possibly see each other in Paris next

\

With best wishes,