1870-1946

American biologist who studied the role of chromosomes in heredity beginning in the 1890s and provided the basis for the study of heredity during the twentieth century. McClung examined the role of chromosomes in sex determination and, based on his belief in the significance of development, argued that the environment played a significant role in determining an individual's sex. He was also active as an administrator and held positions in several prominent scientific organizations, including the National Research Council and the Marine Biological Laboratories at Woods Hole.