Clarence McClung
April 5, 1870 - January 17, 1946
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Scientific Discipline: Cellular and Developmental Biology Membership Type:
Member
(elected 1920)
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Clarence McClung‘s work with grasshopper cells contributed greatly to the theory of the chromosomal basis of heredity. In 1901 McClung hypothesized that sex determination in grasshoppers is dependent upon the number of X chromosomes within a cell. Maleness in grasshoppers is determined by the absence of a second X chromosome (XO), while femaleness is induced by the presence of two X chromosomes (XX). This theory helped to prove that chromosomes carry genetic information that determines phenotype.
McClung graduated from the University of Kansas in 1892 and earned his PhD in 1902. He was appointed professor of zoology and served as the medical school’s dean at the University of Kansas from 1902 to 1906. He served as chairman of the Division of Biology and Agriculture of the National Research Council from 1912 to 1921. He left the University of Kansas in 1912 to head the Zoological Laboratories at the University of Pennsylvania, where he also served as a professor of zoology until 1940.
