FLEXNER, SIMON (1863— ) , American pathologist, was born at Louisville (Ky.), on March 25, 1863. After he gradu ated from the University of Louisville in 1889 he pursued his studies further at Johns Hopkins university and the universities of Strasbourg, Berlin and Prague, and at the Pasteur institute, Paris. He was associate professor and later professor of patho logical anatomy at Johns Hopkins during 1889-99, becoming in 1899 professor of pathology at the University of Pennsylvania. In 1903 he was appointed director of the laboratories of the Rockefeller institute for Medical Research, New York. Dr. Flex ner became widely known in 1905 for his successful treatment of cerebrospinal fever by the use of a serum, the administration of which reduced the mortality rate from 75% in untreated cases to 25% in cases where the serum was used. He has published numerous monographs, on The Pathology of Toxalbumin Intoxi cation, Serum Treatment of Epidemic Meningitis (1917) ; Epi demic Poliomyelitis, Epidemiology.