UNIVERSITY of PENNSYLVANIA PHILADELPHIA 4 The College ZOOLOGICAL LABORATORY 38th St. and Woodland Ave. June 6, 1951 Dr, Joshua Lederberg c/o Dr. M. Jemerec Long Island Biological Laboratory Vold Spring Harbor, Long Island, N. Y. Wear Ur. Lederberg: I know that you have been very busy of late, and you may not have received my letter of May 23. Ur. Raymond Taylor of the A.A.A.S. office wrote that he tried to reach you by telephone last week but was told that you had already left. I very much hope that we may have an early acceptance of our invitation to participate in the symposium on "Sex in Microorganisms" scheduled for the meetings here next December. Someone has suggested that Dr. A. v2. hershey 1s well qualified to present the evidence indicating sex in the viruses, If you would like to share the field with someone else, I should be willing to approacly Ur.. Hershey in regard to participation. Sharing the topic would also invol vee "Ethe alloted to the topic. will you let me know as soon as possible whether“er not you would prefer to have someone take over the virus part of the Sug gested topic, namely, "Evidence for Sex in Bacteria and Viruses", Very sincerely yours, BAe dk DH: RB D.™E. Wenrich