CHEMICAL CORPS BIOLOGICAL LABORATORIES
MM DIVISION

Camp Detrick, Frederick, Moryland

12 December 1951

Dr. Joshua Lederberg
Department of Genetics
University of Wisconsin
Madison, Wisconsin

Tenant eee ns

Dear Josh:

T have just retured from a very pléasant trip to Texas
and had only a little time to check up on some of the points
which we discussed but here is at least sore of the information.

The critical vapor pressure equilibrium for lyophilization
is supposed to be somewhere between 50 and 500 micrdS and closer
to 50 than to 500. I understand that there is a paper by
Greaves in the July issue of the Journal of Hygiene which contains
some additional information. Dr. Bateman has oromised me to
try to write you directly about the new method for separating
cells. As far as the molecular filters are concerned, I understand
that they are not in the open market as yet but should be avail-
able within the near future. I have been told that the firm of
Schleicher and Schuell Company, Keene, New Hampshire, Attn:
Mir. H. A. Holz,is importing the somewhat inferior German model
of this filter and is selling it commercially. This filter,
however, requires water extraction prior to use.

During my trip back to Maryland, it occurred to me that there
may be a trick which Norffen Zinder might use for the so far futile
attempts in transforming rough Salmonella. I understand that
the specific "0" antigen is necessary for the absorption of the
filterable agent and I wonder whether this might not be accomplished
by using the temporary production of S phenotypes in R forms of
Salmonella claimed to be possible in the presence of soluble starch
supplements (see Crossley, Ferguson and Brydson, "The use of
soluble. starch medium in the preparation of smooth "0" Salmonella
antigens", J. Bact., 52, 367-371, 1946.

The contract proposal got here alright and is now in the mills.
I would like to take the opportunity to thank Esther and you
once more for the kind hospitality afforded me during my recent

trip to Madison.

With best regards—

Soyre ty yours ,

CePA TO BDATTIN