Nearly all the later biologists or biological philosophers are as shy of
the term "vital force," and even of the word "vitality," as they are of
the words "soul," "spirit," "intelligence," when discussing natural
phenomena. To experimental science such words have no meaning because
the supposed realities for which they stand are quite beyond the reach
of scientific analysis. Ray Lankester, in his "Science from an Easy
Chair," following Huxley, compares vitality with aquosity, and says that
to have recourse to a vital principle or force to explain a living body
is no better philosophy than to appeal to a principle of aquosity to
explain water. Of course words are words, and they have such weight with
us that when we have got a name for a thing it is very easy to persuade
ourselves that the thing exists. The terms "vitality," "vital force,"
have long been in use, and it is not easy to convince one's self that
they stand for no reality. Certain it is that living and non-living
matter are sharply separated, though when reduced to their chemical
constituents in the laboratory they are found to be identical. The
carbon, the hydrogen, the nitrogen, the oxygen, and the lime, sulphur,
iron, etc., in a living body are in no way peculiar, but are the same as
these elements in the rocks and the soil. We are all made of one stuff;
a man and his dog are made of one stuff; an oak and a pine are made of
one stuff; Jew and Gentile are made of one stuff. Should we be
justified, then, in saying that there is no difference between them?
There is certainly a moral and an intellectual difference between a man
and his dog, if there is no chemical and mechanical difference. And
there is as certainly as wide or a wider difference between living and
non-living matter, though it be beyond the reach of science to detect.
For this difference we have to have a name, and we use the words
"vital," "vitality," which seem to me to stand for as undeniable
realities as the words heat, light, chemical affinity, gravitation.
There is not a principle of roundness, though "nature centres into
balls," nor of squareness, though crystallization is in right lines, nor
of aquosity, though two thirds of the surface of the earth is covered
with water. Can we on any better philosophical grounds say that there is
a principle of vitality, though the earth swarms with living beings? Yet
the word vitality stands for a reality, it stands for a peculiar
activity in matter--for certain movements and characteristics for which
we have no other term. I fail to see any analogy between aquosity and
that condition of matter we call vital or living. Aquosity is not an
activity, it is a property, the property of wetness; viscosity is a term
to describe other conditions of matter; solidity, to describe still
another condition; and opacity and transparency, to describe still
others--as they affect another of our senses. But the vital activity in
matter is a concrete reality. With it there goes the organizing tendency
or impulse, and upon it hinges the whole evolutionary movement of the
biological history of the globe. We can do all sorts of things with
water and still keep its aquosity. If we resolve it into its constituent
gases we destroy its aquosity, but by uniting these gases chemically we
have the wetness back again. But if a body loses its vitality, its life,
can we by the power of chemistry, or any other power within our reach,
bring the vitality back to it? Can we make the dead live? You may bray
your living body in a mortar, destroy every one of its myriad cells, and
yet you may not extinguish the last spark of life; the protoplasm is
still living. But boil it or bake it and the vitality is gone, and all
the art and science of mankind cannot bring it back again. The physical
and chemical activities remain after the vital activities have ceased.
Do we not then have to supply a non-chemical, a non-physical force or
factor to account for the living body? Is there no difference between
the growth of a plant or an animal, and the increase in size of a
sand-bank or a snow-bank, or a river delta? or between the wear and
repair of a working-man's body and the wear and repair of the machine he
drives? Excretion and secretion are not in the same categories. The
living and the non-living mark off the two grand divisions of matter in
the world in which we live, as no two terms merely descriptive of
chemical and physical phenomena ever can. Life is a motion in matter,
but of another order from that of the physico-chemical, though
inseparable from it. We may forego the convenient term "vital force."
Modern science shies at the term "force." We must have force or energy
or pressure of some kind to lift dead matter up into the myriad forms of
life, though in the last analysis of it it may all date from the sun.
When it builds a living body, we call it a vital force; when it builds a
gravel-bank, or moves a glacier, we call it a mechanical force; when it
writes a poem or composes a symphony, we call it a psychic force--all
distinctions which we cannot well dispense with, though of the ultimate
reality for which these terms stand we can know little. In the latest
science heat and light are not substances, though electricity is. They
are peculiar motions in matter which give rise to sensations in certain
living bodies that we name light and heat, as another peculiar motion in
matter gives rise to a sensation we call sound. Life is another kind of
motion in certain aggregates of matter--more mysterious or inexplicable
than all others because it cannot be described in terms of the others,
and because it defies the art and science of man to reproduce.
Though the concepts "vital force" and "life principle" have no standing
in the court of modern biological science, it is interesting to observe
how often recourse is had by biological writers to terms that embody
the same idea. Thus the German physiologist Verworn, the determined
enemy of the old conception of life, in his great work on
"Irritability," has recourse to "the specific energy of living
substances." One is forced to believe that without this "specific
energy" his "living substances" would never have arisen out of the
non-living.
Professor Moore, of Liverpool University, as I have already pointed out
while discussing the term "vital force," invents a new phrase, "biotic
energy," to explain the same phenomena. Surely a force by any other name
is no more and no less potent. Both Verworn and Moore feel the need, as
we all do, of some term, or terms, by which to explain that activity in
matter which we call vital. Other writers have referred to "a peculiar
power of synthesis" in plants and animals, which the inanimate forms do
not possess.
Ray Lankester, to whom I have already referred in discussing this
subject, helps himself out by inventing, not a new force, but a new
substance in which he fancies "resides the peculiar property of living
matter." He calls this hypothetical substance "plasmogen," and thinks of
it as an ultimate chemical compound hidden in protoplasm. Has this
"ultimate molecule of life" any more scientific or philosophical
validity than the old conception of a vital force? It looks very much
like another name for the same thing--an attempt to give the mind
something to take hold of in dealing with the mystery of living things.
This imaginary "life-stuff" of the British scientist is entirely beyond
the reach of chemical analysis; no man has ever seen it or proved its
existence. In fact it is simply an invention of Ray Lankester to fill a
break in the sequence of observed phenomena. Something seems to possess
the power of starting or kindling that organizing activity in a living
body, and it seems to me it matters little whether we call it
"plasmogen," or a "life principle," or "biotic energy," or what not; it
surely leavens the loaf. Matter takes on new activities under its
influence. Ray Lankester thinks that plasmogen came into being in early
geologic ages, and that the conditions which led to its formation have
probably never recurred. Whether he thinks its formation was merely a
chance hit or not, he does not say.
We see matter all about us, acted upon by the mechanico-chemical forces,
that never takes on any of the distinctive phenomena of living bodies.
Yet Verworn is convinced that if we could bring the elements of a living
body together as Nature does, in the same order and proportion, and
combine them in the selfsame way, or bring about the vital conditions, a
living being would result. Undoubtedly. It amounts to saying that if we
had Nature's power we could do what she does. _If_ we could marry the
elements as she does, and bless the banns as she seems to, we could
build a man out of a clay-bank. But clearly physics and chemistry alone,
as we know and practice them, are not equal to the task.