intelligible explanation, we may
feel that we have really grasped the essence of life. If we understand
how the cell can move and grow and reproduce itself, we may rest assured
that the other phenomena of life follow as a natural consequence. If,
therefore, we have obtained an understanding of these fundamental vital
phenomena, we have accomplished our object of comprehending the life
phenomena in our chemical and mechanical laws.

But have we thus reduced these fundamental phenomena to an intelligible
explanation? It must be acknowledged that we have not. We have reduced
them to the action of chemical forces acting in a machine. But the
machine itself is unintelligible. The organic cell is no more
intelligible to us than is the body as a whole. The chemical
understanding which we thought we had a few years ago in protoplasm has
failed us, and nothing has taken its place We have no conception of what
may be the primitive life substance. All we can say is that this most
marvellous of all natural phenomena occurs only within that peculiar
piece of machinery which we call the cell, and that it is the result of
the action of physical forces in that machine. How the machine acts, or
even the structure of the machine, we are as far from understanding as
we were fifty years ago. The solution has retreated before us even
faster than we have advanced toward it.

==Summary.==--We may now notice in a brief summary the position which we
have reached. In our attempt to explain the living organism on the
principle of the machine, we are very successful so far as secondary
problems are concerned. Digestion, circulation, respiration, and motion
are readily solved upon chemical and mechanical principles. Even the
phenomena of the nervous system are, in a measure, capable of
comprehension within a mechanical formula, leaving out of account the
purely mental phenomena which certainly have not been touched by the
investigation. All of these phenomena are reducible to a few simple
fundamental activities, and these fundamental activities we find
manifested by simple bits of living matter unincumbered by the
complicated machinery of organisms. With the few fundamental properties
of these bits of organic matter we can construct the complicated life of
the higher organism. When we come, however, to study these simple bits
of matter, they prove to be anything but simple bits of matter. They,
too, are pieces of complicated mechanism whose action