e are unable
to conceive how dispositions for good or ill lie implicit within the
protoplasmic unit in which the individual life begins. The fact is
undoubted that the initiatives of moral character are in some degree
transmissible, though from the nature of the case the influences of
education, example, environment, and the like are here more potent than
in regard to structural features. We cannot make a silk purse out of a
sow's ear, though the plasticity of character under nurture is a fact
which gives us all hope. Explain it we cannot, but the transmission of
the raw material of character is a fact, and we must still say with Sir
Thomas Browne: "Bless not thyself that thou wert born in Athens; but,
among thy multiplied acknowledgments, lift up one hand to heaven that
thou wert born of honest parents, that modesty, humility, and veracity
_lay in the same egg_, and came into the world with thee."

2. Inheritance of Original Nature[76]

The principles of heredity (may be recapitulated as follows):

First of all, we find useful the principle of the unit-character.
According to this principle, characters are, for the most part,
inherited independently of each other, and each trait is inherited as a
unit or may be broken up into characters that are so inherited.

Next, it must be recognized that characters, as such, are not inherited.
Strictly, my son has not my nose, because I still have it; what was
transmitted was something that determined the shape of his nose, and
that is called in brief a "determiner." So the second principle is that
unit-characters are inherited through determiners in the germ cells.

And finally, it is recognized that there really is no inheritance from
parent to child, but that parent and child resemble each other because
they are derived from the same germ plasm, they are chips from the same
old block; and the son is the half-brother to his father, by another
mother.

These three principles are the three corner stones of heredity as we
know it today, the principles of the independent unit-characters each
derived from a determiner in the germ plasm.

How far are the known facts of heredity in man in accord with these
principles? No doubt all human traits are inherited in accordance with
these principles; but knowledge proceeds slowly in this field.

As a first illustration I may take the case of human eye color. The iris
is made up of a trestle-work of fibers, in which are suspended par