60 THE POPULAR SCIENCE MONTHLY. 



vous temperament favors neuroses ; the lymphatico-sanguine, arthritis 

 and tetter ; and the lymphatic, scrofula. The changes occurring in the 

 physiological equilibrium of an individual have a very definite action 

 on the movements and aspects of constitutional affections. Thus, in- 

 sanity oftentimes appears following menstruation, pregnancy, or child- 

 birth ; and, in like manner, epilepsy and hysteria manifest themselves 

 at the first appearance of the signs of puberty. Education and habits 

 exercise a similar influence. Harsh usage and excessive severity, as 

 also complete lack of discipline and watchfulness, have often deplo- 

 rable effects on the brain of children. Alcoholic excesses and high 

 living are extremely injurious to those whose parents had the gout or 

 the gravel, just as squalor and bad air decimate those who have in 

 themselves the germs of consumption. 



This much at least is certain, that the fatal character of hereditary 

 disease is a great and mournful fact, of which they alone are fully and 

 sadly conscious who have daily to witness its consequences. One must 

 see the premature infirmity, the long-continued suffering, the irrepara- 

 ble catastrophes, the slow, cruel agonies, to which parents oftentimes 

 condemn their children, to form a judgment of the power possessed by 

 the demon of disease which lurks in the depths of their being. We 

 must read the authors who have treated these questions, and especially 

 the great alienists of France, if we would learn w^hat a mysterious and 

 baleful energy is oftentimes brought into the world by the babe as it 

 opens its eyes to the light of day — the poor, innocent, puny creature, 

 which, for this brief moment of illusion, is the object of unbounded 

 joys and blessings, and bright hopes ! 



In short, we may say that the hereditary transmission, whether of 

 individual peculiarities of anatomical structure and of temperament, or 

 of liability to such and such a morbid condition — and the same holds 

 good for certain bodily aptitudes — is a very frequent, though not con- 

 stant, phenomenon in animals and in man. 



Hereditary transmission of individual peculiarities of the mental or 

 affectional kind, and of aptitudes for such and such speculative or 

 moral activities, is also a phenomenon which may be observed, though 

 more rarely than that just mentioned. When we go through the se- 

 ries of instances and authorities got together and cited by certain 

 writers, we are struck, it is true, by the apparent force of their argu- 

 ments, and one is ready to assign to heredity a large share in the de- 

 velopment of intellect and character, in the genesis of the thinking 

 individual. We do not see, we forget, the immense number of facts 

 which stand on the other side. The illusions of these mirages have 

 not been useless, seeing that they have led to researches of great in- 

 terest ; but they would be dangerous if they were to be taken by the 

 public as demonstrating the conclusions drawn by some writers. We 

 will state, in brief, the substantial benefits accruing from the researches, 

 and we will then try to refute the conclusions. 



