Morgan, Thomas Hunt, 1866–1945, American zoologist, b. Lexington, Ky., Ph.D. Johns Hopkins, 1890. He was professor of experimental zoology at Columbia (1904–28) and from 1928 was director of the laboratory of biological sciences at the California Institute of Technology. He is noted for his ingenious demonstration of the physical basis of heredity and the importance of the gene, using in his research the fruit fly, Drosophila. He described the phenomena of linkage and crossing over crossing over, process in genetics by which the two chromosomes of a homologous pair exchange equal segments with each other. Crossing over occurs in the first division of meiosis .
..... Click the link for more information. , which he and his students utilized to map the linear arrangement of genes along the chromosome. Morgan received the 1933 Nobel Prize in Physiology or Medicine. His books, classics in the literature of genetics, include The Physical Basis of Heredity (1919), Mechanism of Mendelian Heredity (rev. ed. 1923), Evolution and Genetics (1925), The Theory of the Gene (rev. ed. 1928), and Embryology and Genetics (1934).

Morgan, Thomas Hunt

(born Sept. 25, 1866, Lexington, Ky., U.S.—died Dec. 4, 1945, Pasadena, Calif.) U.S. zoologist and geneticist. He received his doctorate from Johns Hopkins University. As a professor at Columbia University (1904–28) and California Institute of Technology (1928–45), he conducted important research on heredity. Like many of his contemporaries, Morgan found Charles Darwin's theory of natural selection implausible because it could not be tested experimentally, and he objected to Mendelian and chromosome theories, arguing that no single chromosome could carry specific hereditary traits. His opinion changed as a result of his studies of Drosophila. He developed the hypothesis of sex-linked traits. He adopted the term gene and concluded that genes were possibly arranged in a linear fashion on chromosomes. He was awarded the Nobel Prize in 1933. See also Calvin Blackman Bridges.

Morgan, Thomas Hunt (1866–1945) geneticist; born in Lexington, Ky. Trained as an embryologist, he became a biology professor at Bryn Mawr (1891–1904), where he wrote his first major book, Regeneration (1901). He became a professor at Columbia University (1904–28), and began his revolutionary genetic investigations of the fruit fly Drosophila (1908). Initially skeptical of Gregor Mendel's research, Morgan performed rigorous experiments which demonstrated that genes were indeed discrete chromosomal units of heredity. In 1910 he discovered sex-linkage in Drosophila, and postulated a connection between eye color in fruit flies and human color blindness. With his "fly room" colleagues, he mapped the relative positions of genes on Drosophila chromosomes, then published his seminal book, The Mechanisms of Mendelian Heredity (1915). Followed by some of his Columbia group, he moved to the California Institute of Technology (Caltech) (1928) to continue Drosophila research. In 1933 he received the Nobel Prize in physiology for his studies of the role of chromosomes in heredity. He remained at Caltech until his death, performing administrative duties and pursuing investigations of inheritance in Drosophila, mammals, birds, and amphibians.