396 THE POPULAR SCIENCE MONTHLY. 



liensible 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 indi- 

 viduals composing the race transmit to their descendants charac- 

 teristics 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 transmit- 

 ted 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 adapta- 

 tion 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 char- 

 acteristics 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 be- 

 comes, in consequence of physical, mental, and moral faults, pro- 

 gressively 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 dis- 

 orders bringing on somatic deformities and functional perver- 

 sions incompatible both with the adaptations now necessary and 

 with ancestral adaptations. Harelip, spina bifida, malconforma- 

 tions 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 trans- 

 mitting 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 de- 



