ESTABLISHITD 1895 CABLE ADDRESS “DIFCO” Ihmo LABORATORIES DETROIT 1. A~~~IGCAN i Stanford University Dr. Lederberg Palo Alto, Cal. PHONE WO. l-0800 June 25, 1960 Dear Dr. Lederberg: On several occasions we have had inquiries requesting the formulation of your modified EMB Agar for genetic studies. referred to as EMS Medium of Lederberg. The medium has been We have been unable to find this in the literature and would appreciate your giving us the refer- ence to your publication describing the medium and its uses and if possible to send us reprints' on such articles. Thanking you for this service, I am fd ,.i' c. Yours very sincerely, _ / ,' /_ - '-. 4 ,' I _ . I. ,. 1 _ C .W. Christensen,Ph.D D irector, Microbiology See : Methods in tiedical. Research 1950 3: 5 table 1C Subsequently also used with omission of succinate see: encl. ref. 11.