1856-1939

American cytologist who helped discover the existence and nature of sex chromosomes. Wilson's "The Cell in Heredity and Development" (1928) integrated cell structure and function with heredity, adaptation, and evolution, and helped advance Mendelian genetics. Wilson identified the spiral cleavage of annelids, arthropods, and mollusks, and the radial cleavage of echinoderms, chordates, and vertebrates as the two major patterns of embryo development. Wilson insisted that the scientific method of careful observation, testable hypothesis formulation, and precise experimentation be used throughout biological research.