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. Gallon'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 tendencies to 

 disease." This tendency to revert to the normal average of the race is 

 tEus 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 (haemophilia) 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- 



