A modest Midwesterner who became one of the most influential geneticists of the first half of the 20th century, William E. Castle spent his career at Harvard University and the University of California, Berkeley working on patterns of inheritance in a variety of mammalian taxa. Born in Alexandria, Ohio, on October 25, 1867, Castle graduated from Denison College (1889) and half-heartedly began a career teaching Latin at the University of Ottawa (Kansas). Three years with the classics, however, convinced him that his love of botany might afford a more interesting future. Applying to enter Harvard with the senior class in 1892, he received his A.B., A.M., and Ph.D. in three successive years, during the course of which he became laboratory assistant to Charles B. Davenport and switched to zoology. His dissertation, "The Early Embryology of Ciona intestinalis," provided the first documentation of self-sterility in animals, and was published in the Bulletin of the Museum of Comparative Zoology in 1896.

Like Davenport, Castle acquired an interest in the problems of heredity, and after brief appointments on the faculties at the University of Wisconsin and Knox College, he returned to Harvard in 1897 to begin what would become a forty year career in the department of zoology. Turning to the question of the hereditary basis of sexual differentiation, began large scale breeding experiments using mice and rats, but the rediscovery of Gregor Mendel's theory of inheritance changed the tenor of his work. Castle soon emerged as one of the most ardent of the early Mendelians in the United States. Helping to construct the framework of Mendelism in America -- his article "Mendel's law of heredity" (Proceedings of the American Academy of Arts and Sciences 30 (1903), 543-548) is often considered the first on the topic written by an American -- Castle applied his experimental skills to a variety of fundamental problems in mammalian genetics ranging from studies of the selection of Mendelian characters to the effects of inbreeding to linkage and gene mapping. In one of his best known and characteristically elegant experiments, he and John C. Phillips transplanted the ovaries from a black guinea pig into an albino female and mated that female to an albino male. The progeny of the union were all black, neatly demonstrating that it was the genes, not the soma, that carried hereditary information. While best known for his work on mammals, he was also the first to use Drosophila for genetic experimentation, the organism that became synonymous with the work of Thomas Hunt Morgan.

In 1908, the Bussey Institution at Harvard was reorganized as a graduate school for applied sciences, and Castle relocated his lab, his mice and guinea pigs there, followed by E. M. East in the following year, transforming the Bussey into one of the two most active early centers of genetic study in the country. Castle served as Director of the Bussey until his retirement in 1936, at which time the Bussey was shuttered for economic reasons. Castle's influence, however, continued through the large number of graduate students he mentored who went on to careers in genetics, including C. C. Little, L. C. Dunn, George Snell, Sewall Wright, and Sheldon C. Reed. In a different line, his influence was also felt through his advocacy for scientific eugenics during the 1920s. Although he later repudiated eugenics, his textbook Genetics and Eugenics (1916) was widely used and went through four editions in fourteen years.

After receiving emeritus status from Harvard, Castle refused to retire. Instead, he moved to the West Coast to become a research associate at the University of California, Berkeley and spent an additional twenty five years in research, focusing on the genetics of coat coloration in horses. The last of his 242 scientific papers was published in 1961 at the age of 94. During his long career, he served as an officer for a number of professional societies and received his share of awards, including election to the American Academy of Arts and Sciences (1900), the American Philosophical Society (1910), and the National Academy of Sciences (1915), and he was the first recipient of the Kimber Genetics Award of the National Academy of Sciences in 1955. Castle died in California on June 3, 1962.

Despite the length and importance of his career, the geneticist William E. Castle left only a slender documentary record. He appears to have disposed of old correspondence on a regular basis, and at his death in 1962, little remained. The Castle Papers contain one linear foot of correspondence dating primarily from the period after his "retirement" to the University of California Berkeley in 1936 until his death in 1962, dealing almost exclusively with his research on horse breeding and the inheritance of coat coloration in horses.

Much of Castle's surviving correspondence consists of letters to and from horse breeders, breeders' associations, and clubs for horse and pony breeds regarding the inheritance of coat color and patterns, and less often with other academic geneticists, such as Dewey Steele of the University of Kentucky and Miguel Odroziola of the Estación de Mejora de la Patata in Spain. Castle's most prolific correspondents during the period were Ralph Singleton of the Blandy Experimental Farm in Virginia and Ralph Armstrong, an attorney and pony breeder in Washington state, and like many others, they occasionally sent photographs documenting examples of particular coat colorations or, in the case of Armstrong, hair samples from unusual ponies.

Castle's correspondence with his former student L. C. Dunn is an exception, focusing on mouse genetics while ranging to a variety of other topics including Castle's retirement from Harvard (to make room, he notes, for younger researchers less set in their ways) and the closing of the Bussey Institution to the conduct of scientific research during the Second World War to Castle's interests in the early history of genetics. The collection is arranged alphabetically by writer.

None.

The bulk of the collection was donated by Mrs. Ralph Singleton, 1982, however the letters to and from L. C. Dunn and E. C. MacDowell and Castle's autobiographical and genealogical notes were donated to the APS Library by L. C. Dunn in 1963 (accn. nos. 1963-169ms and 1963-224ms).

Cite as: William Ernest Castle Papers, American Philosophical Society.

Recatalogued by rsc, 2002.

The Castle Papers are also described in Bentley Glass, Guide to the Genetics Collections at the APS.

The Printed Materials Department holds reprints of many of Castle's major works, along with a number of monographs, including:

Castle appears as a correspondent in several collections at the APS, including the papers of George W. Corner (Ms. Coll. 11), Charles B. Davenport (B D27), Milislav Demerec (B D394), and L. C. Dunn (B D917), C. C. Li (B L61), and the University of California Department of Genetics Collection (378.794 C12gen).