int can readily adopt the fact that we do not now observe the
origination of new species; for it is in full harmony with their
metaphysical doctrines, without the same being on that account essentially
dependent upon the confirmation or rejection of the hypothesis of the
present constancy of species. With this very fact, the maxim that if new
species once originated through descent, new species must still originate
through descent, has lost for them its truth, and therefore its power of
demonstration. So we see even here, while in the midst of the discussion of
a purely scientific problem, in what close correlation metaphysics and
natural science stand, and moreover--since the metaphysical view is most
closely connected with the religious--in what close relationship religion
and natural science stand. At the same time we also see how little the
metaphysical interest, and much more how little the religious interest, has
reason to avoid the investigation of facts in nature.

Sec. 4. _The Theory of Evolution--Archaeology, Ethnography, Philology._

The evolution theory teaches that the species have developed themselves one
from another in gradual transitions, each of which was as small as the
individual differences still observed to-day among the individuals of the
same species. It is not without support, especially in the _history of the
development of plants and animals_.

Each organic being becomes what it is by means of organic development. Each
plant, even the highest organized, begins in its seed-germ with a simple
cell, {78} and is differentiated in constant development up to the fully
perfected individual. Each animal, even the most highly organized (man
included), begins the course of its existence as an egg; and each egg has
no greater value of form than that of a single cell. This egg-cell is
differentiated, after fecundation, in gradual and imperceptible
transitions, farther and farther, higher and higher, until the individual
has reached its perfect organization. No organ, no function of the body, no
power or function of the soul or of the mind, appears suddenly, but all in
gradual development. Since we see all individuals thus originating by means
of gradual development, the possibility lies very near that the different
organic formations of all the organic kingdoms could also have been
originated by the same means.

In still another direction does the history of the development of single
plants and animals