But a better definition, based on
the results of genetics, looks at it as a mechanism, not as an external
appearance. From this point of view, heredity may be said to be "the
persistence of certain cell-constituents (in the germ-cells) through an
unending number of cell-divisions."
HETEROZYGOTE (different yolk), a zygotic individual which
contains both members of an allelomorphic pair.
HOMOZYGOTE (same yolk), an individual which contains only one
member of an allelomorphic pair, but contains that in duplicate, having
received it from both parents. A homozygous individual, having been
formed by the union of like gametes, in turn regularly produces gametes
of only one kind with respect to any given factor, thus giving rise to
offspring which are, in this regard, like the parents; in other words,
homozygotes regularly "breed true." An individual may be a homozygote
with respect to one factor and a heterozygote with respect to another.
HORMONES (chain), the secretions of various internal glands,
which are carried in the blood and have an important specific influence
on the growth and functioning of various parts of the body. Their exact
nature is not yet understood.
INBORN usually means germinal, as applied to a trait, and it is
so used in this book.
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