lt. But the fact remains that wherever analysis has
been possible the constituent elements of an organic process prove to be
physical and chemical. Protoplasm differs from inorganic materials only in
its complexity and in the properties which seem to owe their existence to
this complexity. As Huxley points out, it is no more justifiable to
postulate the existence of a vitalistic principle in protoplasm than it
would be to set up an "aquosity" to account for the properties of water,
or a "saltness" for the qualities of a certain combination of sodium and
chlorine. We may not know how the elements produce the properties of the
compound, but we do know that such properties are the invariable products
of their respective constituents in combination. As far as the evidence
goes, it tells strongly and invariably in favor of the mechanistic
interpretation.

Under the present limitations, it is impossible to give this subject the
further discussion it deserves. It is not our purpose to review the origin
of life in times past, and the origin of living matter from inorganic
constituents, though the subject is one of the most important in the field
of cosmic evolution. We must begin with the living organism; and how the
first one arose must be of less importance to us than the knowledge of its
mechanical constitution and of its mechanical operation. Of far greater
value is the realization that a living creature is not an independent
thing, but that, on the contrary, it must hold the closest possible
relations with the world of materials and energies constituting its
environment. We must again insist upon the importance of that mechanical
adjustment to the conditions of life which is the universal characteristic
of plants and animals. It is the history of these creatures and the origin
of their adapted conditions that we are called upon to study. We must
scrutinize the nature of to-day to see if we can find evidence that
evolution is true, and if we can discern the forces which, acting upon the
living mechanism as man has dealt with machines, might bring the various
species of the present day to their modern forms.

* * * * *

We have now learned that evolution means a common ancestry of living forms
that have come to differ in the course of time; our common reason has
shown us also that organisms are in a true sense complicated chemical
mechanisms adapted to meet the conditions under which they must