Definitions
American Heritage® Dictionary of the English Language, Fourth Edition
- n. The theory that all heritable characteristics arise in the germ plasm and that acquired characteristics cannot be inherited.
Century Dictionary and Cyclopedia
- n. The opinions and teachings of August Weismann, a noted German zoölogist and writer on speculative biology. In a memoir on the origin of the sexual cells of hydroids (1883), he showed that the sexual cells which undergo their development in the gonophores of certain hydroids are present, and recognizable, long before the gonophores, the blastostyles which carry them, or the hydranths which carry the blastostyles, come into being; and that the germ-cells reach their destination by long and complicated migrations along definite lines or germ-paths. He was afterward led, by reflection upon these facts and others, to the system of speculations about the nature of inheritance which is known by his name. These consist of the doctrine of germ-plasm together with the logical consequences of its acceptance. Germ-plasm is held to be the substance of inheritance, endowed with a complicated architecture, and never formed anew, being handed down from generation to generation in unbroken continuity. Among the logical consequences, real or assumed, of belief in this theory are: belief that germ-plasm, germ-cells, and unicellular organisms are potentially immortal, or independent of or exempt from natural death; that the development of multicellular organisms always is, has been, and must be, evolution or unfolding of the preexistent; that cell-division is differential, consisting of the division of a cell into two or more with unlike values in inheritance and with unlike predetermined fates; that inheritance is due to the continuity of germ-plasm; that the somatic cells, or those which enter into the composition of the body, are out of the line of descent to future generations and subject to natural death, and that modifications produced in the soma (“acquired characters”) are not and cannot be inherited by descendants, because the somatic cells have no descendants; that certain somatic cells serve as the bearers of germ-plasm along definite cell-paths to the regions of the body where new germ-cells are to be formed; that new hereditary modifications arise only in the germ-plasm through new combinations in sexual reproduction or amphigony; and that among these those that are fittest are preserved according to the principle of natural selection, which is the only and all-sufficient ground of the origin of species.
- n. In popular biological literature, the doctrine or opinion that acquired characters are not, and can not be, inherited. See doctrine of germ-plasm, substance of heredity, acquired character.
GNU Webster's 1913
- n. (Biol.) The theories and teachings in regard to heredity propounded by the German biologist August Weismann, esp. in regard to germ plasm as the basis of heredity and the impossibility of transmitting acquired characteristics; -- often called
neo-Darwinism .
Etymologies
- After August Friedrich Leopold Weismann. (American Heritage® Dictionary of the English Language, Fourth Edition)
Examples
“This may be in a physical sense: Weismannism assumes that intergenerational continuity exists only for germ cell nuclei whereas somatic cells and germ cell cytoplasm arise anew in each generation.”
“Fortuitously initiated development is a condition sine qua non of Darwinism and Weismannism.”
“Weismannism not only retained the principle of utility and selection, but made it the only principle, rejecting entirely the action of external conditions as a cause of congenital modifications, _i. e._ of characters whose development is predetermined in the fertilised ovum.”
“Weismannism that not only sex but all other congenital characters are determined in the fertilised ovum or zygote.”
“Weismannism_ -- occupied a distinguished place in contemporary biology.”
“Of the English, Herbert Spencer, who however, was averse to the vitalistic attitude, Vines and Henslow among botanists, Cunningham among zoologists, have always resisted Weismannism; but, I think, none of these was distinctly influenced by Hering and Butler.”
“Weismannism, therefore, is the inevitable outcome of the straits to which Charles-Darwinians were reduced through the way in which their leader had halted between two opinions.”
“Now let me return to the recent division of biological opinion into two main streams -- Lamarckism and Weismannism Both Lamarckians and”
“The former is sometimes called the theological view, because it recognises the presence in organic nature of design, whether it be called creative power, directive force, directivity, or vital principle; the latter view, in which the existence of design is absolutely negatived, is now usually described as Weismannism, from the name of the writer who has been its principal advocate in recent years.”
“Mr. Wallace, therefore, may well be excused if he casts longing eyes towards Weismannism.”
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