A number of malformations are produced by accidental conditions arising in the environment; for instance, the vascular cord connecting mother and child may become wound around parts constricting them or even cutting them off, and the membrane around the child may become adherent to certain parts and prevent the development of these. The extrinsic causes are more operative the more unfavorable is the environment of the mother. Malformations are more common in illegitimate children than in legitimate and more common in alcoholic mothers; there is an unfavorable environment of poverty in both cases, added to in the latter and usually in the former by the injurious action of the alcohol.

The more extensive malformations have no effect on heredity, because the subjects of them are incapable of procreation. The malformations which arise from the accidents of pregnancy and which are compatible with a perfectly normal germ are in the nature of acquired characteristics and are not inherited. Those malformations, however, which are due to qualities in the germinal material itself are inherited, and certain of them with remarkable persistence. There are instances in which the slight malformation consisting in an excess of fingers or toes has persisted through many generations. It may occasionally lapse in a generation to reappear later. In certain cases, notably in the bleeders, the inheritance is transmitted by the female alone, in other cases by the sexes equally, but there are no cases of transmission by the male line only. It is evident that when the same malformation affects both the male and the female line the hereditary influence is much stronger. A case has been related to me in which most of the inhabitants in a remote mountain valley in Virginia where there has been much intermarriage have one of the joints of the fingers missing. There is a very prevalent idea that in close intermarriage in families variations and malformations often unfortunate for the individual are more common. All experimental evidence obtained by interbreeding of animals shows that close interbreeding is not productive of variation, but that variations existing in the breed become accentuated. Variations either advantageous or disadvantageous for the race or individual may either of them become more prevalent by close intermarriage. It seems, however, to have been shown by the customs of the human race that very close intermarriage is disadvantageous.

Eugenics, which signifies an attempt at the betterment of the race by the avoidance of bad heredity, has within recent years attracted much attention and is of importance. Some of its advocates have become so enthusiastic as to believe that it will be possible to breed men as cattle and ultimately to produce a race ideally perfect. It is true that by careful selection and regulation of marriage certain variations, whether relating to coarse bodily form or to the less obvious changes denoted by function, can be perpetuated and strengthened. That the Semitic race excels in commerce is probably due to the fact that the variation of the brain which affected favorably the mental action conducive to this form of activity, was favorable for the race in the hostile environment in which it was usually placed and transmitted and strengthened by close intermarriage. It is impossible, however, to form a conception of what may be regarded as an ideal type of the human species. The type which might be ideal in a certain environment might not be ideal in another, and environment is probably of equal importance with the material. The eugenics movement has enormously stimulated research into heredity by the methods both of animal experimentation and observation, and study of heredity in man.

As in all of the beginning sciences there is not the close inter-relation of observed facts and theory, but there is excess of theory and dearth of facts. Certain considerations, however, seem to be evident. It would seem to be evident that individuals should be healthy and enabled to maintain themselves in the environment in which they are placed, but the qualities which may enable an individual successfully to adapt himself to factory life, or life in the crowds and strong competition of the city, may not be, and probably are not, qualities which are good for the race in general or for his immediate descendants. At present our attempts to influence heredity should be limited to the heredity of disease only. We can certainly say that intermarriage between persons who have tuberculosis or in whose families the disease has prevailed is disadvantageous for the offspring; the same holds true for insanity and for nervous diseases of all sorts, for forms of criminality, for alcoholism, and for those diseases which are long enduring and transmitted by sexual contact such as syphilis and gonorrhoea. It is of importance that the facts bearing on the hereditary transmission of disease should become of general knowledge, in order that the dangers may be known and voluntarily avoided. No measures of preventive medicine are successful which are not supported by a public educated to appreciate their importance, and the same holds true of eugenics. How successful will be public measures leading to the prevention of offspring in the obviously unfit by sterilization of both males and females is uncertain. It is doubtful whether public sentiment at the present time will allow the measure to be thoroughly carried out. Some results in preventing unfit heredity may be attained by the greater extension of asylum life, but the additional burden of this upon the labor of the people would be difficult to bear. At best such measures would only be carried out in the lower class of society.

New York, Henry Holt And Company.
London, Williams and Norgate, originally published 1913

Tags: Disorders and Diseases