grounds for disbelief in the principle, and also that it lacks
experimental proof.

* * * * *

The explanation of natural evolution given by Darwinism and the principles
of Weismann, Mendel, and De Vries, still fails to solve the mystery
completely, and appeal has been made to other agencies, even to teleology
and to "unknown" and "unknowable" causes as well as to circumstantial
factors. A combination of Lamarckian and Darwinian factors has been
proposed by Osborn, Baldwin, and Lloyd Morgan, in the theory of organic
selection. The theory of orthogenesis propounded by Naegeli and Eimer, now
gaining much ground, holds that evolution takes place in direct lines of
progressive modification, and is not the result of apparent chance. Of
these and similar theories, all we can say is that if they are true, they
are not so well substantiated as the ones we have reviewed at greater
length.

The task of experimental zooelogy is to work more extensively and deeply
upon inheritance and variation, combining the methods and results of
cellular biology, biometrics, and experimental breeding. We may safely
predict that great advances will be made during the next few years in
analyzing the method of evolution; and that a few decades hence men will
look back to the present time as a period of transition like the era of
reawakened interest and renewed investigation that followed the appearance
of the "Origin of Species." For the present, we can justly say "that
evolution, so far as it is understood, is a real and natural process."

V

THE PHYSICAL EVOLUTION OF THE HUMAN SPECIES AND OF HUMAN RACES

The teachings of science that relate to the origin and history of the
human species constitute for us the most important part of the whole
doctrine of organic evolution and now, having completely outlined this
doctrine as a general one, we are brought to the point where we must deal
frankly and squarely with the insistent questions arising on all sides as
to the way that mankind is involved in the vast mechanism of nature's
order. These questions have been ignored heretofore, in order that the
natural history of animals in general might be discussed without any
interference on the part of purely human interest and concern. It now
becomes our privilege, and our duty as well, to employ and apply the
principles we have learned in order to understand more completely the
origin of the human body as an organ