atavism_. Some children resemble their father,
others their mother, and others a kind of mixture of father and
mother.

A closer examination reveals further very curious facts. An infant
which, in its early years, strongly resembles its father, may later on
resemble its mother, or inversely. Certain peculiarities of a certain
ancestor appear suddenly, often at an advanced age. It is needless to
say that peculiarities concerning the beard cannot appear till this
has grown, and this simple fact is so characteristic that it has been
called _hereditary disposition_. Everything may be transmitted by
heredity, even to the finest shades of sentiment, intelligence and
will, even to the most insignificant details of the nails, the form of
the bones, etc. But the combinations of ancestral qualities vary so
infinitely that it is extremely difficult to recognize them.
Hereditary dispositions arise from the energy of two conjugated germs
during the whole of life and till death. Old people sometimes develop
peculiarities hitherto unknown in them, owing to the fact that one or
more of their ancestors also presented the same phenomena at an
advanced age.

_Semon_ has clearly proved that, although forming an infinite number
of combinations the engrams or hereditary energies never blend in the
proper sense of the term, and in the light of his exposition the above
facts are more clearly explained than they had been hitherto. The
experiments of _Mendel_ have shown in plants a certain alteration in
the hereditary ecphorias of the products of dissimilar parents.

Certain parental characters, according as they are added or
subtracted, may disappear during one or two generations, to reappear
all the more strongly in the following generations. In short, there
are a number of phenomena, the laws of which may be more clearly
explained to us in the future.

To sum up, each individual inherits on the average as much from his
paternal as from his maternal side, although the minute nucleus of the
spermatozoid is the only agent concerned on the paternal side, while
the mother provides not only the egg which is much larger, but also
nutrition during the nine months of embryonic life. We can only
conclude that in the egg also it is only from the part of the nucleus
which conjugates with the male nucleus that arise all the inherited
maternal peculiarities; that all the rest is only utilized as food;
and that the nutritive blood of the mother in no w