UNIVERSITE DE PARIS FACULTE DES SCIENCES ' LABORATOIRE o:GENETIQUE 13, RUE PIERRE CURIE, PARIS V’° December 17, 1952 Tél. : ODEon 16-40 Dr. J. LEDERBERG Department of Genetics University of Wisconsin Madison, Wisconsin U.S.A. Dear Josh, I will be very grateful for sending me a reprint of your review in Physiological Reviews. I read it yesterday and was very happy to see that our points of view have considerably converged. You will see that when a little book of mine on "Nucleo-cytoplasmic relations in Microorganisms" (a result of three lectures given last May in Birmingham), which ig presently in press at the Clarendon Press, Oxford, appears. With kind regards to both of you from both of us, ‘ Sincerely, Pom A+ Boris EPHRUSSI