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Born:September 25, 1866LexingtonKentucky...(Show more)Died:December 4, 1945 (aged 79)PasadenaCalifornia...(Show more)Awards and also Honors:Copley Medal (1939)Nobel prize (1933)...(Show more)Notable Works:“The device of Mendelian Heredity”...(Show more)Subjects of Study:Drosophilachromosome mapgenehereditysex-linked character...(Show more)

Thomas hunt Morgan, (born Sept. 25, 1866, Lexington, Ky., U.S.—died Dec. 4, 1945, Pasadena, Calif.), American zoologist and geneticist, famous for his speculative research through the fruit fly (Drosophila) by which he created the chromosome theory of heredity. He confirmed that genes are attached in a collection on chromosomes and also are responsible because that identifiable, hereditary traits. Morgan’s work-related played a vital role in developing the ar of genetics. He got the Nobel Prize because that Physiology or medication in 1933.

Early life

Morgan’s father, Charlton hunting Morgan, was a U.S. Consul, and also his uncle, john Hunt Morgan, had actually been a Confederate military general.


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Early in life, Morgan confirmed an attention in organic history. In 1886 he got the B.S. Level from the State university of Kentucky (later the college of Kentucky) in zoology and also then entered Johns Hopkins college for graduate job-related in biology. In ~ Hopkins, Morgan studied under the morphologist and also embryologist william Keith Brooks. After being awarded the Ph.D. In 1890, Morgan remained there a year prior to accepting a teaching short article at Bryn Mawr College.

Experiments in embryology

During the period 1893–1910, Morgan applied experimental methods to an essential problems that embryology. In bespeak to identify causally connected events throughout development, that analyzed such troubles as the development of embryos from separated blastomeres (early embryonic cells) and also fertilization in nucleated and also nonnucleated egg fragments. As examples of the effects of physics factors, that analyzed the method in i beg your pardon the spatial orientation of egg affects their future advancement and the action of salt concentration ~ above the advance of fertilized and unfertilized eggs. In 1904 that married one of his graduate students in ~ Bryn Mawr, Lillian V. Sampson, a cytologist and embryologist of significant skill. The very same year, he accepted an invite to assume the professorship of speculative zoology in ~ Columbia University, where, throughout the next 24 years, he carried out most of his crucial research in heredity.

Like most embryologists and many biologist at the revolve of the century, Morgan discovered the Darwinian concept of advancement lacking in plausibility. The was complicated to conceive of the development of complicated adaptations simply by an accumulation of slight opportunity variations. Moreover, Darwin had listed no mechanism of heredity come account for the beginning or transmission of variations, other than his early and also hypothetical theory of pangenesis. Back Morgan believed that development itself to be a fact, the device of natural selection proposed by Darwin seemed incomplete since it might not be placed to an speculative test.

Morgan had quite various objections come the Mendelian and chromosome theories. Both theories attempted to explain organic phenomena by postulating systems or product entities in the cell that somehow control developmental events. Come Morgan this was as well reminiscent the the preformation theory—the idea that the totally formed adult is current in the egg or sperm—that had dominated embryology in the 18th and early 19th centuries. Return Morgan admitted the the chromosomes might have something to execute with heredity, he said in 1909 and 1910 the no solitary chromosome might carry specific hereditary traits. He additionally claimed the Mendelian theory was completely hypothetical: return it might account for and even predict breeding results, it can not explain the true procedures of heredity. The each pair that chromosomes separates, with the individual chromosomes climate going into different sperm or egg cell in exactly the very same manner as Mendelian factors, did no seem come be adequate proof come Morgan for claiming that the 2 processes had actually anything to carry out with every other.

The occupational on Drosophila

Morgan apparently began breeding Drosophila in 1908. In 1909 he it was observed a little but discrete variation well-known as white-eye in a single male paris in among his culture bottles. Aroused through curiosity, he bred the fly v normal (red-eyed) females. All of the offspring (F1) to be red-eyed. Brother–sister matings among the F1 generation created a second generation (F2) with some white-eyed flies, every one of which were males. To define this curious phenomenon, Morgan emerged the theory of sex-limited—today dubbed sex-linked—characters, which the postulated were component of the X-chromosome of females. Other genetic variations developed in Morgan’s stock, plenty of of which were additionally found to be sex-linked. Since all the sex-linked characters were usually inherited together, Morgan came to be convinced that the X-chromosome carried a number of discrete hereditary units, or factors. He adopted the ax gene, which was introduced by the Danish botanist Wilhelm Johannsen in 1909, and concluded that gene were probably arranged in a straight fashion ~ above chromosomes. Much to his credit, Morgan rubbish his skepticism around both the Mendelian and also chromosome theories when he witnessed from 2 independent currently of evidence—breeding experiments and cytology—that one can be treated in regards to the other.


sex-linked inheritance
Sex-linked inheritance of white eyes in Drosophila flies.
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In teamwork with A.H. Sturtevant, C.B. Bridges, and also H.J. Muller, who were graduates in ~ Columbia, Morgan quickly arisen the Drosophila work right into a large theory the heredity. Particularly important in this occupational was the demonstration that each Mendelian gene could be assigned a particular position along a straight chromosome “map.” further cytological work showed the these map positions can be figured out with an accurate chromosome regions, thus providing definitive proof the Mendel’s factors had a physical communication in chromosome structure. A summary and presentation the the beforehand phases the this work-related was released by Morgan, Sturtevant, Bridges, and also Muller in 1915 as the influential book The mechanism of Mendelian Heredity. to varying degrees Morgan also accepted the Darwinian concept by 1916.

In 1928 Morgan was invite to to organize the department of biologic of the California institute of Technology. The was likewise instrumental in developing the naval Laboratory ~ above Corona del Mar together an integral component of Caltech’s biology training program. In subsequent years, Morgan and his coworkers, consisting of a variety of postdoctoral and graduate students, continued to intricate on the countless features of the chromosome concept of heredity. Towards the end of his stay at Columbia and much more so after relocating to California, Morgan self slipped away from the technological Drosophila work and began to return to his earlier interest in experimental embryology. Although aware of the theoretical links between genetics and development, he found it an overwhelming at that time to attract the connection explicitly and to assistance it with experimental evidence.

In 1924 Morgan got the Darwin Medal; in 1933 he to be awarded the Nobel Prize because that his discovery of “hereditary transmission mechanisms in Drosophila”; and also in 1939 he to be awarded the Copley Medal by the Royal culture of London, of i m sorry he was a foreign member. In 1927–31 he offered as president of the nationwide Academy that Sciences; in 1930 the the American Association because that the development of Science; and also in 1932 the the Sixth worldwide Congress of Genetics. He stayed on the faculty at Caltech till his death.

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Among Morgan’s many important books are those dealing with (1) evolution: Evolution and Adaptation (1903), in i m sorry he strong criticizes Darwinian theory; and also A Critique of the concept of Evolution, (1916), a an ext favourable watch of the an option process; (2) heredity: Heredity and also Sex (1913), his first major exposition the the Mendelian device in relation to Drosophila; and also with A.H. Sturtevant, H.J. Muller, and also C.B. Bridges, The system of Mendelian Heredity (1915; rev. Ed., 1922); and also The concept of the Gene (1926; enlarged and also revised ed., 1928); the latter two works firmly developed the Mendelian theory as it used to heredity in all multicellular (and numerous unicellular) organisms; and (3) embryology: The development of the Frog’s Egg: An development to experimental Embryology (1897), a comprehensive outline that the developmental step of frogs’ eggs; Experimental Embryology (1927), Morgan’s explain on the value of experimentation in embryology; and also Embryology and Genetics (1934), an attempt to relate the concept of the gene to the trouble of embryological differentiation and development.