Page:Popular Science Monthly Volume 34.djvu/235

Rh to-day have been at work for ages upon ages. That was no sarcasm, but the plainest statement of scientific truth, on the part of Oliver Wendell Holmes, when, after declaring his conviction that every disease might be cured if taken in season, he added, significantly, that in some cases it would be necessary to begin a hundred years before the patient was born. This is a hard world, and no weakling ever has half a chance. "The survival of the fittest" is a merciful provision of nature. "The strongest live and the weakest die." A race of criminals, paupers, and idiots deteriorates with each successive generation, and goes down to speedy extinction. It is the robust, sturdy, clear-headed, strong-handed toiler of to-day, whose sons and daughters will inhabit homes of wealth and occupy positions of responsibility a few years hence.

The effects of unfavorable heredity may be manifested in various ways. In the first place, the child may be born with the disease already developed. Examples of this class may be seen in hypertrophies, atrophies, and inflammations of various organs; in exudations, as hydrocephalus; in infantile syphilis; in new growths, such as nævus, tumors, and certain forms of cancer; in the pre-natal deposition of tubercles, parasites, and some inorganic products; in arrests of development, such as cleft-palate, hare-lip, spina bifida, and that defective closure of the heart which produces cyanosis; and in those unusual developments known as monstrosities. Secondly, the disease may be transmitted, although its manifestations are not developed at birth. This may be the case with some of the diseases already mentioned as also occurring in the first class, as well as with many others. Examples are seen in scrofula, cancer, consumption, epilepsy, rheumatism, gout, insanity, and the "specific" disease. Again, there may be no actual disease, but only a tendency to disease, in the shape of an inherited weakness of some special organ or in some particular direction. These tendencies render their possessors unduly liable to suffer from particular diseases, but do not make it necessary that they should do so, provided that their environment is favorable. Lastly, the faulty heredity may be manifest only in a general weakness of the whole system, a lack of vigor and vitality, which renders its possessor an easy victim to whatever malady may attack him. This is the cause of many of the deaths which are registered under the heads of infantile debility, diarrhœa, brain-disease, and other common affections of infancy.

To the actual diseases, special weaknesses, and unsound constitutions resulting from unfavorable heredity, add now the environment of poverty, with its usual accompaniments of ignorance, carelessness, and inefficiency on the part of the parents, resulting for both parents and children in privation of food, clothing,