we do not even
hope to understand. That their action is dependent upon their machinery
is evident enough from the simple description of cell activity which we
have noticed. That these fundamental vital properties are to be
explained as the result of chemical and mechanical forces acting through
this machinery, can not be doubted. But how this occurs or what
constitutes the guiding force which corresponds to the engineer of the
machine, we do not know.

Thus our mechanical explanation of the living machine lacks a
foundation. We can understand tolerably well the building of the
superstructure, but the foundation stones upon which that structure is
built are unintelligible to us. The running of the living machine is
thus only in part understood. The living organism is a machine or, it
is better to say, it is a series of machines one within the other. As a
whole it is a machine, and its parts are separate machines. Each part is
further made up of still smaller machines until we reach the realm of
the microscope. Here still we find the same story. Even the parts
formerly called units, prove to be machines, and when we recognize the
complexity of these cells and their marvellous activities, we are ready
to believe that we may find still further machines within. And thus
vital activity is reduced to a complex of machines, all acting in
harmony with each other to produce together the one result--life.

PART II.

_THE BUILDING OF THE LIVING MACHINE_.

* * * * *

CHAPTER III.

THE FACTORS CONCERNED IN THE BUILDING OF THE LIVING MACHINE.

Having now outlined the results of our study into the mechanism of the
living machine, we turn our attention next to the more difficult problem
of the method by which this machine was built. From the facts which we
have been considering in the last two chapters it is evident that the
problem we have before us is a mechanical rather than a chemical one. Of
course, chemical forces lie at the bottom of vital activity, and we must
look upon the force of chemical affinity as the fundamental power to
which the problems must be referred. But a chemical explanation will
evidently not suffice for our purpose; for we have absolutely no reason
for believing that the phenomena of life can occur as the results of the
chemical properties of any compound, however complex. The simplest known
form of matter which manifests life is a machine, and the problem of the