reserves its
configuration at all times and places during the ontogeny. External
stimuli impign upon the organism usually at a definite point, but they
not only effect a local transformation of the idioplasm but also
reproduce themselves in a dynamic manner in the entire idioplasm, which
is in unbroken connection throughout the whole individual. The idioplasm
is thus changed everywhere in the same manner, so that the germ cells
that are given off at any point feel and inherit the effects of those
local stimuli.

In the formation of the germ cells in sexual reproduction, the
idioplasms of both parents must come into contact with each other,
whereupon there results either a material union and formation of a mixed
idioplasm or perhaps rather a dynamic action; and through these agencies
there is produced a remodeled form which is, however, exactly equivalent
to the combined idioplasms entering into it. Fertilization by diosmose
of the spermatic substance is impossible.[D]

[D] This assertion is a direct corollary from the structure of
the determinants and the idioplasm. If the idioplasm of the
fertilizing cell were to pass through the membrane about the
ovum by osmosis, its organized structure would be
lost.--_Trans._

In the idioplasm of a germ cell arising from the crossing of unlike
individuals the micellar rows of the individual determinants have
sometimes an intermediate constitution and produce characteristics in
the organism which are intermediate between the characteristics of the
parents. Sometimes the micellar rows derived from the father and mother
respectively lie side by side unchanged in the idioplasm of the
offspring in distinct groupings and may reproduce in the organism their
respective characteristics side by side, or only one of them may
develop, while the other remains latent.

On account of the union of both idioplasms as the result of fecundation,
two sexually mature organisms are the more able to form with each other
a viable germ cell, the nearer they are genetically related--that is,
the more nearly the male and female idioplasms correspond in their
configuration and chemical nature, because in this case the micellar
arrangements are best suited to each other, and the idioplasm of the new
fertile germ cell receives its most suitable nourishment from the
mother. If, however, self-fecundation or the closest in-and-in breeding
often yields products of less virility and is avoid