pee

February 21, 1953

Dr. E. J. Csarneteky
Wileon and Company
Chicago Tllinoia

Bear Dr, Czarnetaky:

A few days ago, & was visiting P. R. Edwards at Chamblee,Ga., and
happened to refer to the preservation technique outlined in the enclosed
eiroular. In the coures of our conversation, he referred to a process
of which he had heard from you, and which may be based on a similar prin-
ciple. If you can make available any additional details, I would appre-
ciate hearing about them.

The ciroular ie more discouraging, perhaps, than it might be. In pre-
vious private discussions, I had been optimistic and I did not want to
mishead any of my friends into relying on thie technique until it had been
thoroughly tested. It will be a good many yeara before this can be done;
our own results have been, on the whole quite good and better than repre-
eented, but not always reproducible. More researeh is needed on at least
three points:

1) the best medium on which to dry the oells themselves

2) optimal residual free water (as I suspect some failures may have
been due to overdrying)

%) optimal suspending medium-—— some of my colleagues using this
method have had better luck with serum or milk.

These empirical problems would be better solved, and in my own mind
are superseded by more fundarental biophysical atudies on "suspended ani-
mation", to which relatively little thought has been given on the theoretical
elda.

Do you know of anyone else following up thie line of work? Dr. Freeman
Wehes, at the Type Culture Collection has been planning to do some studies,
as I understand, on this silica gel procedure.

Yours sincerely,

Joshua Lederberg
Associate Professor of Genetics

SILICA GEL