There seems to have been of late years a marked reaction, even among men
of science, from the mechanistic conception of life as held by the band
of scientists to which I have referred. Something like a new vitalism is
making headway both on the Continent and in Great Britain. Its exponents
urge that biological problems "defy any attempt at a mechanical
explanation." These men stand for the idea "of the creative
individuality of organisms" and that the main factors in organic
evolution cannot be accounted for by the forces already operative in the
inorganic world.
There is, of course, a mathematical chance that in the endless changes
and permutations of inert matter the four principal elements that make
up a living body may fall or run together in just that order and number
that the kindling of the flame of life requires, but it is a disquieting
proposition. One atom too much or too little of any of them,--three of
oxygen where two were required, or two of nitrogen where only one was
wanted,--and the face of the world might have been vastly different. Not
only did much depend on their coming together, but upon the order of
their coming; they must unite in just such an order. Insinuate an atom
or corpuscle of hydrogen or carbon at the wrong point in the ranks, and
the trick is a failure. Is there any chance that they will hit upon a
combination of things and forces that will make a machine--a watch, a
gun, or even a row of pins?
When we regard all the phenomena of life and the spell it seems to put
upon inert matter, so that it behaves so differently from the same
matter before it is drawn into the life circuit, when we see how it
lifts up a world of dead particles out of the soil against gravity into
trees and animals; how it changes the face of the earth; how it comes
and goes while matter stays; how it defies chemistry and physics to
evoke it from the non-living; how its departure, or cessation, lets the
matter fall back to the inorganic--when we consider these and others
like them, we seem compelled to think of life as something, some force
or principle in itself, as M. Bergson and Sir Oliver Lodge do, existing
apart from the matter it animates.
Sir Oliver Lodge, famous physicist that he is, yet has a vein of
mysticism and idealism in him which sometimes makes him recoil from the
hard-and-fast interpretations of natural phenomena by physical science.
Like M. Bergson, he sees in life some tendency or impetus which arose in
matter at a definite time and place, "and which has continued to
interact with and incarnate itself in matter ever since."
If a living body is a machine, then we behold a new kind of machine with
new kinds of mechanical principles--a machine that repairs itself, that
reproduces itself, a clock that winds itself up, an engine that stokes
itself, a gun that aims itself, a machine that divides and makes two,
two unite and make four, a million or more unite and make a man or a
tree--a machine that is nine tenths water, a machine that feeds on other
machines, a machine that grows stronger with use; in fact, a machine
that does all sorts of unmechanical things and that no known combination
of mechanical and chemical principles can reproduce--a vital machine.
The idea of the vital as something different from and opposed to the
mechanical must come in. Something had to be added to the mechanical and
chemical to make the vital.
Spencer explains in terms of physics why an ox is larger than the sheep,
but he throws no light upon the subject of the individuality of these
animals--what it is that makes an ox an ox or a sheep a sheep. These
animals are built up out of the same elements by the same processes, and
they may both have had the same stem form in remote biologic time. If
so, what made them diverge and develop into such totally different
forms? After the living body is once launched many, if not all, of its
operations and economies can be explained on principles of mechanics and
chemistry, but the something that avails itself of these principles and
develops an ox in the one case and a sheep in the other--what of that?
Spencer is forced into using the terms "amount of vital capital." How
much more of it some men, some animals, some plants have than others!
What is it? What did Spencer mean by it? This capital augments from
youth to manhood, and then after a short or long state of equilibrium
slowly declines to the vanishing-point.
Again, what a man does depends upon what he is, and what he is depends
upon what he does. Structure determines function, and function reacts
upon structure. This interaction goes on throughout life; cause and
effect interchange or play into each other's hands. The more power we
spend within limits the more power we have. This is another respect in
which life is utterly unmechanical. A machine does not grow stronger by
use as our muscles do; it does not store up or conserve the energy it
expends. The gun is weaker by every ball it hurls; not so the baseball
pitcher; he is made stronger up to the limit of his capacity for
strength.
It is plain enough that all living beings are machines in this
respect--they are kept going by the reactions between their interior and
their exterior; these reactions are either mechanical, as in flying,
swimming, walking, and involve gravitation, or they are chemical and
assimilative, as in breathing and eating. To that extent all living
things are machines--some force exterior to themselves must aid in
keeping them going; there is no spontaneous or uncaused movement in
them; and yet what a difference between a machine and a living thing!
True it is that a man cannot live and function without heat and oxygen,
nor long without food, and yet his relation to his medium and
environment is as radically different from that of the steam-engine as
it is possible to express. His driving-wheel, the heart, acts in
response to some stimulus as truly as does the piston of the engine, and
the principles involved in circulation are all mechanical; and yet the
main thing is not mechanical, but vital. Analyze the vital activities
into principles of mechanics and of chemistry, if you will, yet there is
something involved that is neither mechanical nor chemical, though it
may be that only the imagination can grasp it.
The type that prints the book is set up and again distributed by a
purely mechanical process, but that which the printed page signifies
involves something not mechanical. The mechanical and chemical
principles operative in men's bodies are all the same; the cell
structure is the same, and yet behold the difference between men in
size, in strength, in appearance, in temperament, in disposition, in
capacities! All the processes of respiration, circulation, and nutrition
in our bodies involve well-known mechanical principles, and the body is
accurately described as a machine; and yet if there were not something
in it that transcends mechanics and chemistry would you and I be here? A
machine is the same whether it is in action or repose, but when a body
ceases to function, it is not the same. It cannot be set going like a
machine; the motor power has ceased to be. But if the life of the body
were no more than the sum of the reactions existing between the body and
the medium in which it lives, this were not so. A body lives as long as
there is a proper renewal of the interior medium through exchanges with
its environment.
Mechanical principles are operative in every part of the body--in the
heart, in the arteries, in the limbs, in the joints, in the bowels, in
the muscles; and chemical principles are operative in the lungs, in the
stomach, in the liver, in the kidneys; but to all these things do we not
have to add something that is not mechanical or chemical to make the
man, to make the plant? A higher mechanics, a higher chemistry, if you
prefer, a force, but a force differing in kind from the physical forces.
The forces of life are constructive forces, and work in a world of
disintegrating or destructive forces which oppose them and which they
overcome. The mechanical and the chemical forces of dead matter are the
enemies of the forces of life till life overcomes and uses them; as much
so as gravity, fire, frost, water are man's enemies till he has learned
how to subdue and use them.