F. W. Mott.Medicine and Eugenics.401
recognised, however, that this law only applied to masses of people and not
to individual cases, for he says : “ Though one half of each child may
be said to be derived from either parent, yet he may receive a heritage from
a distant progenitor that neither of his parents possessed as personal char
acteristics.” Again, speaking of Particulate Inheritance, he remarks; “ All
living beings are individuals in one aspect, composite in another. We seem
to inherit bit by bit this element from one progenitor, that from another,
in the process of transmission by inheritance elements derived from the
same ancestor are apt to appear in large groups, just as if they had clung
together in the pre-embryonic stage, as perhaps they did.” They form
what is well expressed by the word traits—traits of feature and character,
that is to say, continuous features, not isolated points. The offspring of
parents possess a mosaic of inheritance bearing usually a more or less
similarity, yet the mosaics of character, whether bodily or mental, are
not in any way identical, except in the case of identical twins. Now,
there is a reason for this. Identical twins are the result of fertilization of
one ovum containing two germs of identical substance, and this leads rne
to refer to Galton’s remarkable inquiry into the History of Twins in con
nection with Nature and Nurture. He found that similar twins living in a
different environment nevertheless remained similar in temperament and
character, while dissimilar twins brought up and living in the same environ
ment remained dissimilar; these dissimilar twins, however, were the product
of two separate ova with dissimilar germs. This shows that every germ has
a specific energy of its own, as manifested by a different potential
inheritance. Galton also made a statistical inquiry into good and bad tempers, and
as a result of this inquiry he says : “It now becomes clear enough and
may be taken for granted that the tempers of progenitors do not readily
blend in the offspring, but that some of the children take mainly after one
of them, some after another, but with a few threads, as it were, of
various ancestral tempers woven in, which occasionally manifest themselves.
If no other influences intervened, the tempers in the children of the same
family would on this account be almost as varied as those of their ancestors.
To recapitulate briefly, one set of influences tends to mix good and bad
tempers in a family at haphazard; another tends to assimilate them, or
that they shall all be good or all be bad; a third set tends to divide each
family into contracted portions. These facts, ascertained by Galton, are.
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. DD
