Aaron Franklin Shull

James Marion Shull (1872–1948). He grew up on the family farm, learning first hand about agriculture and plants. After an informal early schooling, he received an AB from the University of Michigan in 1908 and briefly joined the Michigan Biological Survey. He then joined Columbia University where he became interested in heredity, inspired by T. H. Morgan and E. B. Wilson. He examined the influence of environmental factors on development. He received a PhD in 1911 and became a zoology instructor at the University of Michigan. He began to examine sex determination in rotifers and conducted experiments on mutation induction and crossing in Drosophila. He also conducted experiments on insect biology and took a special interest in polymorphisms such as in the presence or absence of wings in aphids. Shull was a critical opponent of suggestions on mimetic relationships based on human visual observation. He would point out that W. L. McAtee showed from stomach contents of birds that mimics and models were eaten in proportion to their availability. He believed that care needed to be taken to examine the predator and their perception.^[2] He was an evolutionist but believed that many of the contemporary researchers were too descriptive and lacking rigour in their claims. In his teaching he believed that there had to be specific principles including cell organization, genetics, systematics and distribution rather than merely descriptions of "type specimens". He also believed that a purely historical approach to teaching biology did not help unify the field.^[3]

Elizabeth Shull Russell.^[4]