YALE UNIVERSITY DEPARTMENT OF MICROBIOLOGY 310 CEDAR STREET NEW HAVEN 11, CONNECTICUT June 7, 1961 Dr. Joshua Lederberg Department of Genetics Stanford University Medical School Stanford, California Dear Josh: I can be reached at my New Haven address until July 17th. On July 18th I shall fly to Paris and continue immediately to Marseille. On July 20th I can be reached in Marseille in the lab of Jaques Senez C.N.R.S., 66 rue St. Sebastien, Marseille. That weekend I will go to England and at least part of the time I can be reached vis Sidney Elsden, Department of Microbiology, The University, Sheffield. Before leaving England I will check with Sidney whether he has any messages for me. From Monday, July 3lst, through Saturday, Augugt 5th, I shall be in Sweden and can be reached c/o Julius Neumann, Ekbaksvagen 7, Nasby Park, Stockholm, Sweden. August 6th and 7th I shall be in Leningrad, the hotel address is not yet known, and starting August 8th in Moscow where I can presumably be reached through the Congress. Please give my best regards to Esther. Sincerely, Wolf Vishniac WV: jtv P.S, Starting September 1 my address will be : Department of Biology, University of Rochester, Rochester 20, New York. . C 1 DEMS, (A