evolution in its own way, how it confirms the law of recapitulation
demonstrated by comparative embryology, and how it proves that the greater
and smaller divisions of animals have followed the identical order in
their evolution that the comparative study of the present day animals has
independently described.

* * * * *

The facts of geographical distribution constitute the fifth division of
zoölogy, and an independent class of evidences proving the occurrence of
evolution. This department of zoölogy assumed its rightful status only
after the other divisions had attained considerable growth. Many
naturalists before Darwin and Wallace and Wagner had noticed that animals
and plants were by no means evenly distributed over the surface of the
globe, but until the doctrine of evolution cleared their vision they did
not see the meaning of these facts. As in the case of all the other
departments of zoölogy the immediate data themselves are familiar, but
because they are so obvious the mind does not look for their
interpretation but accepts the facts at their face value. While the
phenomena of distribution are no less fascinating to the naturalist, and
no less effective in their demonstration of evolution, their comprehensive
treatment would demand more space than the whole purpose of the present
description of organic evolution would justify. Thus a brief outline only
can be given of the salient principles of this subject in order that their
bearing upon the problem of species may be indicated.

Even as children we learn many facts of animal distribution; every one
knows that lions occur in Africa and not in America, that tigers live in
Asia and Malaysia, that the jaguar is an inhabitant of the Brazilian
forests, and that the American puma or mountain lion spreads from north to