Heredity and eugenics in relation to insanity / by F.W. Mott.

  • Frederick Walker Mott
Date:
[1912]
Catalogue details

Licence: In copyright

Credit: Heredity and eugenics in relation to insanity / by F.W. Mott. Source: Wellcome Collection.

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    of great interest in connexion with the inheritance of the predisposition to nervous and mental diseases, a predisposition which is termed the neuro pathic taint. Galton’s law of filial regression again seems to explain many facts regarding the inheritance of feeble-mindedness as well as ability. In respect to the latter, Galton showed that only a few out of many children would be likely to differ from mediocrity as their mid parent, and still fewer would differ as widely as the more exceptional of the two parents. The more bountifully the parent is gifted by nature, the more rare will be his good fortune if he begets a son as richly endowed as himself, and still more so if he begets a son who is endowed yet more largely. But the law is even-handed, it levies an equal succession tax on the succession of badness as of goodness. If it discourages the extravagant hopes of a gifted parent that his children will inherit all his powers, it no less discountenances extravagant fears that they will inherit all his weaknesses and tende?icies to diseaseThis tendency to revert to the normal average of the race is thus a great factor in heredity. Amphimixis, or the blending of the in¬ heritances of two individuals, is claimed by Weismann as the great factor in the production of variation and evolution, but when a functional and structural dynamic equilibrium has been established in all the organs and tissues of the body for a species and race, amphimixis would act in an opposite manner in tending to prevent the perpetuation of variation, patho¬ logical or otherwise. Change of type comes about through inheritance of modification, and many abnormalities and defects, arising we know not why, are transmitted through successive generations, and apparently are not swamped out by dilution unless they interfere with self-preservation or with marriage selection and propagation. I may cite the following as examples : Polydactylism, six fingers and six toes; brachydactylism, short fingers, lobster claw hand, white tufts of hair, various eye and skin diseases. A remark¬ able example of an hereditary visual defect is congenital stationary night blindness which has continued through nine generations, affecting 135 members out of close on 2,000 descendants (Nettleship and Cunier). Colour blindness, and the tendency to bleed (hoemophilia) are curious affections limited to the male sex but transmitted by the females. Then we have those tendencies to disease affecting stocks, e.g., tuberculosis, rheumatism, diabetes, gout, and nervous and mental diseases, or neuropathic tendency. In the case of tuberculosis and rheumatism the tendency is shown by a weak¬ ness in defence against specific and ubiquitous microganisms. In gout and diabetes there is a tendency in the stock to disease arising from a disturbance of the bio-chemical equilibrium of the blood in relation to the functions of the organs and tissues of the body and nutrition. The neuropathic diathesis may also be due to an inherent tendency to a disturbance of the bio-chemical equilibrium of the blood and the nervous system occurs, especially in the brain, or the potential energy stored is nervous and mental diseases, a predisposition which is termed the neuro-