Washington, D.C. Carnegie Institution of Washington, 1905; 1906. Two volumes. 8vo. 32; [ii], 33-74 pp., including bibliography in both volumes. FIRST EDITION. With 15 total plates. Original publisher’s cloth, library markings on front covers, tear in first free endpaper of Volume II, interiors otherwise excellent. Bookplates of Cornell University Library noting the gift on Hon. A.D. White (withdrawn stamp), and the ownership signature of Mark A. Cukierski. Item #15960
First edition of this monumental study of chromosomal sex determination in the sperm and egg cells of insect species, an early example of XY sex-determination. The work describes Stevens’ research on the generation of sperm cells (spermatogenesis) and their role in the fertilization of egg cells, with a focus on chromosomal differences in sperm cells. Part I, published in 1905, investigates a theory first noted by Clarence Erwin McClung, that an odd number of chromosomes found in insects from some species formed a basis of sexual determination by which an extra chromosome caused cells to differentiate differently than normal. Stevens investigates the theory as a potential sex determination mechanism. The results of additional research are published in Part II, which focuses on beetles, and her search for sexual differentiation mechanisms in similar species to confirm sex determination by a distinct chromosomal element. Stevens devotes much of her work describing chromosomes in both germ cells (precursor cells to egg and sperm cells) and somatic cells and her ability to determine which chromosome will result in the development of a male or female. Stevens provides one of the first observations of XY sex-determination, allowing researchers to locate the material of Mendelian inheritance that passed specific traits through a distinct chromosomal element.
Studies in spermatogenesis influenced biologists such as Thomas Hunt Morgan and Edmund Beecher Wilson, who, after Stevens published her results in Part I, revised his previous publications, deleting references to environmental influences. Stevens (1861-1912) studied at Stanford and then Bryn Mawr. Along with Wilson, the previous head of the biology department there, she was the first researcher to describe the chromosomal basis of sex.