November 18, 1946.
Director of Research Development,
Atlas Powder Co.,
Wilmington, Delaware.
Dear Sir:

This letter is inspired by the report cf Dubos and Davis (J.—Exp. Med.,
83:409-423 1946. Factors affecting the growth of tubercle bacilli in lighid
media.) that the product Tween 80 (polyoxyethylene sorbitan mono-oleate)
was exceedingly efficacious in promoting the diffuse growth of tubercle
bacilli. We would apprediate it very much if a sample of about 20 g.
of this material could be made avalaable to test whether it would have similar
properties in influencing the growth of other bacteria and of yeast,
which would greatly facilitate researches we are conducting on these organisms,

Very sigjcerely yours,

Joshua Lederberg,