Jamuary 2, 1952

Dr. H. H. McKinney

Division of Cereal Crops and Diseases
U. S. DB. AL

Belteville, Md.

Dear Dr. MeKinney:

Thaticyyou for calling my attention to your paper on virus preservation.
I don't have a well-worked out uebhed for preservation on a silica gel, only
an idea on which T've Jone a few papsriments. I simply thought that. cne
could dry culture’ dfrectly con a chemically inert dessicant such as anhy-—
drous silica gol. The problem is in roughly the same state as your own
experience-— a design that looks good, but will have to be worked out
in detail.

I would imagine that silica geil ought to work very weil with plant viruses,
but I have no experience along this line. Al} I have done has been to add
a desase suspension of bacteria to about twenty parts of silica gel
(Davidson So., Baltimore, Grade 40) in a small tube, then seal off in air.
The material dkhes down almost imnediately. Survival has been arratic:
probably the best menstrun should be worked out. The silica tubes are
baked beforehand to sterilize and dehydrate them, and are then kept in
a vacuum dessicator.

I am pisasad in your interes? in this, and hope that you or your staff
may be cbh.e to give some attention to it. It is the sort of thing that noone
is likely to want to handle unless they ure closely concerned with preservation
problems. On the other hand, I think that the blophysigs of preservation
of living corgmaiams is a subject ci the deepest theoretical im ortance, about
which we are woefully ignorant.

Sincerely,

Joshua sederberg
Associate Professor of Ganetics