402Section IV.F. W. Mott.
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
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 by which an insufficient storage of potential energy in the
nervous system occurs, especially in the brain, or the potential energy stored is
unstable, consequently there is an inherent failure to control its conversion
into active energy as in epilepsy and other paroxysmal nervous states.
The discovery of Mendelism has opened up a new and vast field of investi
gation, and although so far Mendelian analysis is as yet imperfectly developed
in respect to human inheritance, yet as Bateson says : “ Organisms may be
regarded as composed to a great extent of separate factors, by virtue of
which they possess their various characters or attributes. These factors
are detachable, and may be recombined in various ways. It thus becomes
