UNIVERSITY of PENNSYLVANIA PHILADELPHIA 4 The College ZOOLOGICAL LABORATORY 38th St. and Woodland Ave. May 16, 1951 ’ Dr. Joshua Lederberg University of “isconsin Madison, Wisconsin Dear Dr. Lederberg: I am trying to organize a symposium on "Sex in microorganisms" for the meetings of the A. A. A. S. to be held in rhiladelphia next December. This symposium is to be sponsored by Section G (Botany) and Section F (Zoolorsy) of the Association. Two sessions are planned, one for each Section. Yor the Botanical Section it seems desirable to have a paper on the evidences for sex in bacteria end viruses, one on sex in fungi, and one on sex in unicellular algae. Dr. W. G. Hutchinson has given me your name as the man to give us the report on bacteria and viruses. ‘Will you, therefore, let me know at the earliest possible moment whether or not you can participate in this symposium in the way suggested. If you find it impossible to do so, will you please suggest one or more men who could give us a paper on the subject indicated. an early reply is urgent. Very Sincerely yours, D. He. Jenrich DIM: se