ISTITUTO SUPERIORE DI SANITA Rome, January 12th, 1953 ROMA VIALE REGINA MARGHERITA, 2399 Doctor Joshua Lederberg, College of Agriculture, University of Wisconsin, Madison, Wisconsin Dear Dr.Lederberg, As you probably know the next International Congress of Microbiology is due to take place in Rome on September Sth to 10th. The provisional programme foresees 6 Symposia and over 20 sections. The subjects of the Symposia will be the foliowing: 1) Microbial Metabolism, 2) Nutrition and Growth Factors, 3) Growth Inhibition and Chemotherapy, 4) Host-Virus Relationship, 5) Bacterial Cytology, 6) Actinomycetes, The Symposia will consist of lectures of a dura= tion of about 30 to 45 minutes, given by specialists in their respective fields; each lecture will be followed by a discussion of about 15 minutes. The lectures of the Symposia will be published in spe= cial monographs and must be in the hands of the Organising Committee not later than April 1st, 1953. The Symposia will be organized under the au= Spices of the Istituto Superiore di Sanita. Dr.Harry Eagle who is the Scientific Director of the Symposium on Growth Inhibition and Chemo= therapy has suggested that we should contact you to ask you whether you would prepared to give a lecture within the framework of the Symposium on Growth Inhibition and Chemotherapy on the subject of Genetic Aspects of Drug Resistance. Unfortunately the Organising Committee has no funds to cover your travel expenses but will be glad to carry your Hotel and maintainance expenses in Rome during the Congress. ISTITUTO SUPERIORE DI SANITA ROMA MIALE REGINA MARGHERITA, 289 Your active participation in the Symposium on Growth Inhibition and Chemotherapy will be a most valuable contribution towards the scientific success of the Congress and I very much hope you will be able to accept the invitation. If you agree to give one of the Symposia lectures you will receive an official invitation from Prof. D.Marotta in his capacity as Director General of the Institute. Hoping to hear from you soon, Yours very sincerely, th. Cho, ( E.B.Chain, F.R.S.) scientific Director International Research Centre for Chemical Microbiology