selection" within the
germ-plasm, influencing it, and being influenced by it--for instance,
restrained.

In order to explain the mystery of heredity, Weismann long ago elaborated,
in his germ-plasm theory, the doctrine that the developing individual is
materially preformed, or rather predetermined in the "idants" and "ids" of
the germ-cell. Thus every one of its physical characters (and, through
these, its psychical characters), down to hairs, skin spots, and
birth-marks, is represented in the "id" by "determinants" which control
the "determinates" in development. In the course of their growth and
development these determinants are subject to diverse influences due to
the position they happen to occupy, to their quality, to changes in the
nutritive conditions, and so on. Through these influences variations in
the determinants may be brought about. And thus there comes about a
"struggle" and a process of selection among the determinants, the result
of which is expressed in changes in the determinates, in the direction of
greater or less development. On this basis Weismann attempts to reach
explanations of the phenomena of variation, of many apparently Lamarckian
phenomena, and of recognised cases of "orthogenesis," and seeks to
complete and deepen Roux's theory of the "struggle of parts," which was
just another attempt to carry Darwinism within the organism.

What distinguishes Weismann, and makes him especially useful for our
present purpose of coming to an understanding in regard to the theory of
selection is, that his views are unified, definite and consistent. In his
case we have not to clear up the ground and to follow things out to their
conclusions, nor to purge his theories from irrelevant, vitalistic, or
pantheistic accessory theories, as we have, for instance, in the case of
Haeckel. His book, too, is kept strictly within its own limits, and does
not attempt to formulate a theory of the universe in general, or even a
new religion on the basis of biological theories. Let us therefore inquire
what has to be said in regard to this clearest and best statement of the
theory of selection when we consider it from the point of view of the
religious conception of the world.

Whatever else may be said as to the all-sufficiency of natural selection
there can be no doubt that it presupposes two absolute mysteries which
defy naturalistic explanation and every other, and which are so important
that in comparison with them