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a speculative theory of heredity and development.
According to Hippocrates, who lived in the fifth and fourth centuries B.C., close physical resemblances between children and their parents were caused by the fact that in animals and man “the seed separates from the rest of the body.” Similar views were developed in the 17th century by G. Borelli and in the 18th century by G. Buffon. In 1868, C. Darwin advanced the concept of pangenesis in his “provisional hypothesis of pangenesis.” Attempting to encompass in a single theory the phenomena of individual development and of variability, heredity, and phylo-genetic development, Darwin suggested that submicroscopic germs called gemmules migrate from all parts of the body through the circulatory system to the sex cells. The gemmules ensure that descendants will develop characteristics similar to those of their parents, including newly acquired characteristics. Darwin’s hypothesis received neither support nor empirical confirmation. Thus, F. Galton, attempting in 1871 to ascertain whether there are gemmules in the blood that determine the color of hair, transfused blood from dark-colored rabbits to light-colored ones and found that the transfusion caused no change in the coloring of the offspring. Darwin’s hypothesis of pangenesis is important in that it contains the concept, later confirmed, of the discreteness, or corpuscular nature, of the material basis of heredity.
Intracellular pangenesis, a hypothesis advanced by H. de Vries in 1889, suggested that hereditary instincts are caused by the presence of material particles (pangens) in living protoplasm. In contrast to Darwin, de Vries denied that pangens were transferred to the sex cells; he believed that each cell nucleus from its very inception contains all the pangens distinctive to a given individual. Elements of de Vries’ hypothesis have been proven valid in modern biology, especially since the successful transplantation of somatic cell nuclei to egg cells without nuclei has proved that complete genetic information is contained in the nuclei of the body’s cells.
REFERENCESDarwin, C. Soch., vol. 4. Moscow-Leningrad, 1951.
Vries, H. de. Intracellulare Pangenesis. Jena, 1889.
L. IA. BLIAKHER