nce it is
highly favourable to the victory of our modern doctrine of evolution
that its chief problem, the question as to the origin of species, is
being more and more pressed by these opposite alternatives: Either all
organisms are naturally evolved, and must in that case be all
descended from the simplest common parent-forms--or: That is not the
case, and the distinct species of organisms have originated
independently of each other, and in that case can only have been
created in a supernatural way, by a miracle. Natural evolution, or
supernatural creation of species--we must choose one of these two
possibilities, for a third there is not.

But as Virchow, like many other opponents of the doctrine of
evolution, constantly confounds this latter proposition with the
doctrine of descent, and that again with Darwinism, it will not be
superfluous to indicate here, in a few words, the limitation and
subordination of these three great theories.

I. The general doctrine of development, the progenesis-theory or
evolution-hypothesis (in the widest sense), as a comprehensive
philosophical view of the universe, assumes that a vast, uniform,
uninterrupted and eternal process of development obtains throughout
all nature; and that all natural phenomena without exception, from the
motions of the heavenly bodies and the fall of a rolling stone to the
growth of plants and the consciousness of men, obey one and the same
great law of causation; that all may be ultimately referred to the
mechanics of atoms--the mechanical or mechanistic, homogeneous or
monistic view of the universe; in one word, Monism.

II. The doctrine of derivation, or theory of descent, as a
comprehensive theory of the natural origin of all organisms, assumes
that all compound organisms are derived from simple ones, all
many-celled animals and plants from single-celled ones, and these last
from quite simple primary organisms--from monads. As we see the
organic species, the multiform varieties of animals and plants, vary
under our eyes through adaptation, while the similarity of their
internal structure is reasonably explicable only by inheritance from
common parent-forms, we are forced to assume common parent-forms for
at least the great main divisions of the animal and vegetable
kingdoms, and for the classes, orders, and so forth. Thus the number
of these will be very limited, and the primitive archigonian
parent-forms can be nothing else than monads. Whether we f