July 24, 1946
Dear Dr. Lederberg:
I have sent you under separate cover reprints that are still available of my papers and will keep you on my mailing list in the future.
The reference I promised to send you on the chromosomes of Paramecium is to an article by Wenrich that appeared in 1940 in the Collective Net, 15:1-6. There is also a list of chrosome numbers given in Kudo's Protozoology, 1946, page 149. I hope this will be of some help to you.
With best wishes for continued success in your work,
Cordially yours,
T.M. Sonneborn