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Page:Popular Science Monthly Volume 4.djvu/70

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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, insanity oftentimes appears following menstruation, pregnancy, or childbirth; 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 deplorable 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 irreparable 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 what 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 constant, 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 series of instances and authorities got together and cited by certain writers, we are struck, it is true, by the apparent force of their arguments, and one is ready to assign to heredity a large share in the development 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 interest; 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.