Page:Popular Science Monthly Volume 15.djvu/452

 Optimists assure us that even if insanity, idiocy, deaf-mutism, blindness, and intractable disease and deformity be upon the increase, the evil is not unmingled with good, as it at once serves the twofold purpose of illustrating and exercising the benevolence of the age.

The only rational interpretation that can be put upon the manifestations of defective blood is, that they are the prodroma of its extinction. If the genetic conditions are continuously applied, such will be, as familiar experience often illustrates, the ultimate result; the salient points of the process being, a large infant mortality, death before reproduction, and infertility. On the theory of Dr. N. Allen, that increase of population is mainly governed by the law of approximation to perfection in bodily structure and harmony of function, the postulate can be easily proved that, as a people, we are gradually but surely degenerating. Dr. Toner, the compiler of vital statistics at the national capital, has found that "there is undoubted evidence of a gradual decline in the proportion of children under fifteen to the number of women between fifteen and fifty years of age throughout our country."

The vital statistics of Rhode Island have been carefully and intelligently collected for many years by Dr. Snow, who states that there has been a gradual decline in the birth-rate among those of American parentage for the last twenty years. The same is true of Massachusetts, and, in fact, of New England; the birth-rate being actually lower than in any country of Europe, France alone excepted.

The causes of race degeneration are usually very complex; some pertaining to environment, others to a faulty personal hygiene. Through heredity all the evil effects are accumulated and perpetuated. But fortunately there is a principle in life which tends to antagonize and obliterate the destructive tendency of these innate defects upon life. If nothing of the kind existed—if there were no opposing force—the failure of physiological action would be rapid, uniform, and progressive, until morbid energy gained its fatal mastery over that which tends to hold organic structure in a cycle of harmonious changes.

What is known as reversion, and termed by Darwin "the great principle of inheritance," furnishes the clearest conception of this opposing energy. Of its essential cause nothing is known, but as to its steady operation there is indubitable evidence. In two well-defined conditions of organic life, its steady influence may be observed: in processes that are normal, and in those that are abnormal. The influence of reversion in the perpetuity of normal characters is fully recognized, but the same can not be said of its true relation to those that are abnormal. Writers who have treated upon this point apparently consider the principle as one which tends to restore a lost character without regard to its nature, or, in other terms, that a quality ill suited for the continuance of life, and which has disappeared for one or more generations, is quite as likely to reappear as one well suited. This