Page:Popular Science Monthly Volume 47.djvu/408

396 that evolutionary disorders of the nervous system due to morbid heredity or provoked by influences of the medium may exist without external morbid aberrations. Furthermore, many lesions of the centers met with in neuropathic families in which no external deformities have been found have been attributed to evolutionary troubles of the nervous system.

A race is formed by the fixing of the specific characteristics transmissible by sexual generation. The families and the individuals composing the race transmit to their descendants characteristics of the family and individual characteristics combining themselves in infinite variety to constitute personalities which are yet capable of differing only in limited measure. When the specific qualities that characterize the race cease to be transmitted by heredity; when the children in a family cease to resemble their parents and their brothers and sisters without recovering an ancestral type, and there results a defective change in the adaptation to the physical and social medium, we say that the race is degenerating. By degeneration should be understood the loss of the hereditary qualities that have determined and fixed the characteristics of the race. The characteristic of what is called in human races morbid heredity, which is simply a degeneration, is an abnormal tendency to variation in the posterity, which becomes, in consequence of physical, mental, and moral faults, progressively capable of adapting itself. In the artificial races of domestic animals the result of degeneration is often reversion to a primitive type of the species with capacity to recover the old adaptations. The designation race has in this case been really given to variety, the hereditary qualities of which had not the fixity that characterizes a race. No reversions are observed in the natural races. In the human races in particular degeneration is not manifested, whatever some authors may have said about it, by returns to ancestral forms, but rather by evolutionary disorders bringing on somatic deformities and functional perversions incompatible both with the adaptations now necessary and with ancestral adaptations. Harelip, spina bifida, malconformations of the genital organs, so frequent in degenerates, have nothing to do with ancestral types; and sterility, which is the inevitable outcome of degeneration, can have but little relation to atavism. Considering the matter more closely, we find that the vices in the conformation of degeneration, which we call the stigmata of degeneration, are teratological deformities. If the degenerate fails to give origin to beings that resemble him, it is not because he has acquired the special faculty of transmitting characteristics that do not belong to him, but because degeneration is the dissolution of heredity.

The similarity which we find in the human species among