Page:Popular Science Monthly Volume 83.djvu/39

Rh species, an inhibitory mechanism by which the expected reaction may be stopped. The inhibitory mechanism (aside from its usefulness to the individual) is a device for protecting the community from reactions that, however favorable originally to the individual, are antisocial. Children at birth have the inhibitors undeveloped, but they have a marvelous capacity for acquiring them in some or all forms. Many a person, however, unfortunately for himself and society, is incapable of acquiring the full complement of them; he tends constantly or periodically, throughout life and despite the best training, to react directly to the stimulus that falls upon him, antisocial though the reaction may be. Such a person may have perfect "society manners" and be faithful in conjugal relations but on occasion will take from shops articles for which she has no need; or another is regarded as a valuable member of his community, a leading member of the bar and a pillar of the church, but about once a year consumes a nearly lethal quantity of alcoholic drinks; or another is an agreeable, generous, affectionate young fellow who, about once a month, secretly sets fire to buildings in order to feed an irresistible love of the excitement produced by the flames; or a young girl who does well at school starts out from a comfortable home ostensibly to go to Sunday School, but makes it a practise of spending the afternoon in the rooms of some marines; or a lad of refined home, beloved of his parents and loving them, slips out of doors instead of going to bed at night and sleeps in entry ways or wanders out into the country and spends the night in a barn. These are examples, among hundreds that could be cited, of a lack of specific inhibitions. The stimulus can not be shunted off; it must lead to the specific response. Just as the amoeba throws out its pseudopods along the path of the incident ray and so moves from the source of light; as the moth flies towards the candle; as the carrion fly is directed in its movements by the scent wafted to it from afar, so such persons perform their unsocial acts as part of their necessary reactions.

In another set of cases every reaction to a stimulus is of a socially desirable sort. All desires for the property of others, all inclinations to avenge insult by violence, all tastes and appetites, including the sex instinct, are readily inhibited—are under perfect control. And why are they under control? Because, first, the person who has the inhibitors came from a fertilized egg that carried the determiners for them; and, secondly, was surrounded by influences that were favorable to their development. In what sense can these people be held to be equal before the law with those considered in the preceding paragraph?

Even in numerous elements of mood and behavior the influence of the hereditary make-up is striking. One person is prevailingly elated, jovial, irrepressible; another quiet, depressed, melancholic; another, still, alternates in these moods and when elated he believes he can do