Pangenesis

Pangenesis, a hypothesis put forward by Darwin in 1868 in his Variation of Plants and Animals under Domestication to explain the facts of heredity. It supposes all the cells of an organism to throw off inconceivably minute gemmules, which multiply by self-division and are capable of developing into cells similar to those from which they are derived. By mutual affinity these gemmules are collected into the sperm-cells and germ-cells of the organism, so that the offspring of the union of sperm and germ combines gemmules from all parts of each parent's body. A large number of gemmules are supposed to be transmitted in a dormant state to future generations, thus explaining the phenomena of reversion or atavism. This hypothesis has been opposed by that of Mr. Herbert Spencer, of physiological units, and by Professor Weismann's hypothesis of "the continuity of the germ-plasm." [Weismann.]