USE - INHERITANCE. The Lamarekian principle of the transmission by heredity of characters acquired during the lifetime of the individual; they are contrasted with congenital characters. That slight lesions are not trans mitted was apparently proved by the experi ments of \Veismann in docking the tails of white mice for nineteen generations, and his finding that such a mutilation was not transmitted. At the present time the alleged transmission of mutilations or various lesions, as tattooing or flattening of the head, is not proved. On the other hand, the Lamarckian principle of the in heritance of characters formed by adaptation to changes in the physical environment, changes of climate, as well as those resulting from use or disuse, or any kind of external stimulus, al though denied by 1Veismann and his followers, have not been disproved. Adaptation to a differ ent medium from that of their ancestors, as in the case of birds and insects, is the result of use-inheritance. Very obvious examples are the cetaceans where, by change from terrestrial to aquatic habits. the legs have been converted into fin-like members. Another instance is the ac quired habit of pointing in the pointer breed, cases being known of young dogs pointing with out having been trained. The habit of holding the tail erect is an acquired one in dogs, as the wolf and fox never elevate the tail. The senile expression of the face in children of old parents is claimed to be an example of such inheritance. Such examples as these prove that, as Eimer states, every character formed by the functional activity of the animal is an acquired character.
The changes begin during the lifetime of the in dividual, become transmitted (or at least the tendency), until after a number of generations, the new conditions becoming permanent, the new characters are formed, and these are preserved by use-inheritance.
The experimental proofs of use-inheritance have accumulated sufficiently to prove that, where the changed climate, or temperature and moisture or dryness of the air, remain the same, the new characters arc transmitted. In plants, where use or disuse do not come into play, the changes of station, of climate, temperature, soil, and nu trition. when permanent, result in the formation of new varieties and species, according to the La marckian principle. It is maintained that the transmission of acquired diameters, struc tural, physiologieal, and mental, is demanded by the theory of evolution. Weismann's objection to use-inheritance is that modifications of the animal are acquired anew every individual life and cannot be transmitted. It remains to be seen whether this criticism will withstand the mass of data now being accumulated. Consult the writings of Lamarck, Darwin, Koelliker, Eimer. Cope, Herbert Spencer. Gallon, Hyatt, 11'eismann, Standfuss, Fischer. Packard, Piepers, Kidd, and others. See EVOLUTION; HEREDITY.