the problem of the struggle for efficacy and
its meaning fades into insignificance. These are the functions and
capacities of living organisms in general, and in particular those of
variation and inheritance, of development and self-differentiation. What
is, and whence comes this mysterious power of the organism to build itself
up from the smallest beginnings, from the germ? And the equally mysterious
power of faithfully repeating the type of its ancestors? And, again, of
varying and becoming different from its ancestors? Even the "mechanical"
theory of selection is forced to presuppose the secret of life. Weismann
indeed attempts to solve this riddle through his germ-plasm theory, the
predisposition of the future organism in the "ids," determinants, and
biophors, and through the variation of the determinants in germinal
selection, amphimixis and so on. But this is after all only shifting the
problem to another place, and translating the mystery into algebraical
terms, so to speak, into symbols with which one can calculate and work for
a little, which formulate a definite series of observations, an orderly
sequence of phenomena, which are, however, after all, "unknown quantities"
that explain nothing.

In order to explain the developing organism Weismann assumes that each of
its organs or parts, or "independent regions," is represented in the
germ-plasm by a determinant, upon the fate of which the development of the
future determinate depends. It is thought of as a very minute corpuscle of
living matter. Thus there are determinants of hairs and scales, pieces of
skin, pits, marks, &c. But every determined organ, or part, or
"independent region," is itself in its turn an "organism," is indeed a
system of an infinite number of interrelated component parts, and each of
these again is another, down to the individual cells. And each cell is an
"organism" in itself, and so on into infinity. Is all this represented in
the determinants? And how?

Further, the individual determinate, for instance of a piece of skin, is
not something isolated, but passes over without definite boundary into
others. Therefore the determinants also cannot be isolated, but must be
systems within systems, dependent upon and merging into one another. How,
at the building up of the organism, do the determinants find their
direction and their localisation? And, especially, how do they set to work
to build up their organ? Here the whole riddle of the the