july 31, 1948.
Dr. Ym. Burrows,
Dept. “Jacterlology,
University of Chicago,
Chicazo 37, Tllinois.
Dear Burrows,

You aay bs interested to hear that our first fairly conclusdve teats
for recombination in a Salmonella (a monophasic typhi~mriun) have been
very disappointing. Two double mutants (tryptephane-,arabinose-) and
(Asoleucine/valine-, calactose-) were secured, and plated on glucose syn-
thetic medium. A very few prototropha have apneared, but so far they have
showed no recombinations of the feremntation characters, and are assuzed to
ba reverse-mitants for the nutritional rejuirements, such as are occasionally
found in the separate cultures. I hope that "your" girl is doing better.

Ne are moving on to some other strains.

Rith best regards,

Tours sincerely,

Joshua Lederberg
Assistant Professer of Genetics.

 

 

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