304 Heredity. 



customs, religious ideas, institutions, and laws, which often are 

 very influential in determining the degeneration of a race. In the 

 east, the harem, with its life of absolute ignorance and complete 

 indolence, has, through physical and moral heredity, led to the 

 rapid decay of various nations. * We have no harem in France,' 

 says a naturalist, ' but there are other causes, quite different in 

 their origin, which tend ultimately to lower the race. In our day, 

 paternal affection, with the assistance of medical science, more 

 certain, and possessed of more resources, makes more and more 

 certain the future of children, by saving the lives of countless weak, 

 deformed, or otherwise ill-constituted creatures that would surely 

 have died in a savage race, or in our own a century or two ago. 

 These children become men, they marry, and by heredity transmit 

 to their descendants at least a predisposition to imperfections 

 like their own. Sometimes both husband and wife bring each a 

 share to this heritage. The descendants go on degenerating, and 

 the result for the community is debasement, and, finally, the disap- 

 pearance of certain groups.' l 



The only way of getting a clear idea of a case of psychological 

 and moral decay, hereditarily transmitted, is by finding for it some 

 organic cause. The physiology and anatomy of the brain are not 

 yet sufficiently advanced to explain it ; we cannot say to what 

 change in the brain such and such a decay of intellect, or such and 

 such a perversion of the will, is to be attributed. But cerebral 

 phenomena and psychical phenomena are so closely connected 

 that a variation of the one implies a variation of the other. 



This being assumed, let us take a man of average organization, 

 physically and morally. Let us suppose that, in consequence of 

 disease, outward circumstances, influences coming from his sur- 

 roundings or from his own will, his mind is impaired, to only a 

 trifling extent it may be, but yet permanently. Clearly heredity 

 has nothing to do with this decay ; but then, if it is transmitted to 

 the next generation, and if, further, the same causes go on acting in 

 the same direction, it is equally clear that heredity in turn becomes 

 a cause of decay. And if this slow action goes on with each new 

 generation it may end in total extinction of intellect 



* JRevtu da Cours Sdentifiques, vol. vL p. 690. 



