Sonneborn, Tracy M.

Sonneborn, Tracy M. (Morton) (1905–81) geneticist; born in Baltimore, Md. He was a National Research Council fellow (1928–30), moved to Johns Hopkins (1930–39), then joined the University of Indiana (1939–76), remaining active after his retirement. He discovered crossbreeding and mating types in paramecia (1937), thus integrating the genetic principles known in multicellular organisms with that of protozoa. He wrote many books and professional articles dealing with mitochondrial inheritance, nuclear differentiation, and the relationship of genetics and the environment.