Dear Professor Browning:

It was most thoughtful and gracious of you to forward
a copy of the "Paul Fhrlich Centennial" sympcsium. I was
actively reading the university library's copy when yours
arrived, and I am delighted to have it for my own library.

I suppose you had in mind particularly the design of
experiments on selective recombination, which are the main
preoccupation of this laboratory, and which you had antictpated
in your early trypanosome experiments.

Since 190 there have been a number of not very credible
reports on sexuality in trypanosomes. It cccurs to me that the time might be
ripe to reopen the questicn with a more comprehensive application of the same
design. It would be appropriate to try to "cross" a irger varlety of strains
and species, to use various #ifferent drug-resistance Markers, and so forth.
Perhaps this has bean done on a larger scale than was indicated in 1908. If
not, I would earnestly ask that you consider the matter further: there would
hardly be anyohe more appropriately qualified.

Under separate cover I an sending another offprint that may interest
you, this tims of a talk at the dedication of Waksman's research Institute
of Rinkagx Microbiology, held last June. I wish I could also send you Dr.
van Niel's article, but the book is now in print. I must express my whole-
hearted agreement with van Niel's closing paragpaph, but siso my discourage-
ment at his hope, which is the contrast of Ehrlich's Institute and the present
one.

Yours sincerely,

Joshua Lederberg
Professor of Genetics