UNITED STATES DEPARTMENT OF AGRICULTURE
AGRICULTURAL RESEARCH ADMINISTRATION

BUREAU OF PLANT INDUSTRY, SOILS, AND
AGRICULTURAL ENGINEERING
DIVISION OF BELTSVILLE, MARYLAND

CEREAL CROPS AND DISEASES
December 31, 1951

Dr. Joshua Lederburg
Department of Genetics
College of Agriculture
University of Wisconsin
Madison, Wisconsin

Dear Dr. Lederburg:

I understand that you have developed a method of preserving bacteria
on the granules of a silica jel. Can you send me a reprint or give
me the citation dealing with this method?

I am enclosing a reprint in which is described a method of preserving
plant viruses in situ by means of chemical dehydration at cool temper-
atures. I have found that the use of anhydron (anhydrous magnesium
perchlorate) in the storage bottles extends the period of viability

of the viruses that have been tested,

Thanking you for any information you may be in a position to give ,
I am,

Sincerely yours,

Sy | 4,

AAHE Ks Ji FL
H. H. McKinney |
Senior Pathologist