born 1877, Utica, N.Y., U.S.
died Nov. 10, 1916, Kansas City, Kan.
U.S. geneticist.
He received a medical degree from Columbia University and practiced surgery the rest of his life. In 1902 he provided the earliest detailed demonstration that somatic chromosomes (those in cells other than sex cells) occur in distinct pairs of like chromosomes, hypothesizing that chromosomes carry the units of inheritance and that their behaviour during meiosis is the physical basis of Gregor Mendel 's concept of heredity. In 1903 he concluded that chromosomes contain units of heredity (now known as genes) and that their behaviour during meiosis is random. His work formed the basis for the chromosomal theory of heredity .