Life goes up-stream--goes against the tendency to a static equilibrium
in matter; decay and death go down. What is it in the body that
struggles against poisons and seeks to neutralize their effects? What is
it that protects the body against a second attack of certain diseases,
making it immune? Chemical changes, undoubtedly, but what brings about
the chemical changes? The body is a _colony_ of living units called
cells, that behaves much like a colony of insects when it takes measures
to protect itself against its enemies. The body forms anti-toxins when
it has to. It knows how to do it as well as bees know how to ventilate
the hive, or how to seal up or entomb the grub of an invading moth.
Indeed, how much the act of the body, in encysting a bullet in its
tissues, is like the act of the bees in encasing with wax a worm in the
combs!
What is that in the body which at great altitudes increases the number
of red corpuscles in the blood, those oxygen-bearers, so as to make up
for the lessened amount of oxygen breathed by reason of the rarity of
the air? Under such conditions, the amount of hæmoglobin is almost
doubled. I do not call this thing a force; I call it an
intelligence--the intelligence that pervades the body and all animate
nature, and does the right thing at the right time. We, no doubt, speak
too loosely of it when we say that it prompts or causes the body to do
this, or to do that; it _is_ the body; the relation of the two has no
human analogy; the two are one.
Man breaks into the circuit of the natural inorganic forces and arrests
them and controls them, and makes them do his work--turn his wheels,
drive his engines, run his errands, etc.; but he cannot do this in the
same sense with the organic forces; he cannot put a spell upon the pine
tree and cause it to build him a house or a nursery. Only the insects
can do a thing like that; only certain insects can break into the
circuit of vegetable life and divert its forces to serve their special
ends. One kind of an insect stings a bud or a leaf of the oak, and the
tree forthwith grows a solid nutlike protuberance the size of a
chestnut, in which the larvæ of the insect live and feed and mature.
Another insect stings the same leaf and produces the common oak-apple--a
smooth, round, green, shell-like body filled with a network of radiating
filaments, with the egg and then the grub of the insect at the centre.
Still another kind of insect stings the oak bud and deposits its eggs
there, and the oak proceeds to grow a large white ball made up of a kind
of succulent vegetable wool with red spots evenly distributed over its
surface, as if it were some kind of spotted fruit or flower. In June, it
is about the size of a small apple. Cut it in half and you find scores
of small shell-like growths radiating from the bud-stem, like the seeds
of the dandelion, each with a kind of vegetable pappus rising from it,
and together making up the ball as the pappus of the dandelion seeds
makes up the seed-globe of this plant. It is one of the most singular
vegetable products, or vegetable perversions, that I know of. A sham
fruit filled with sham seeds; each seed-like growth contains a grub,
which later in the season pupates and eats its way out, a winged insect.
How foreign to anything we know as mechanical or chemical it all
is!--the surprising and incalculable tricks of life!
Another kind of insect stings the oak leaf and there develops a pale,
smooth, solid, semi-transparent sphere, the size of a robin's egg, dense
and succulent like the flesh of an apple, with the larvæ of the insect
subsisting in its interior. Each of these widely different forms is
evoked from the oak leaf by the magic of an insect's ovipositor.
Chemically, the constituents of all of them are undoubtedly the same.
It is one of the most curious and suggestive things in living nature. It
shows how plastic and versatile life is, and how utterly unmechanical.
Life plays so many and such various tunes upon the same instruments; or
rather, the living organism is like many instruments in one; the tones
of all instruments slumber in it to be awakened when the right performer
appears. At least four different insects get four different tunes, so to
speak, out of the oak leaf.
Certain insects avail themselves of the animal organism also and go
through their cycle of development and metamorphosis within its tissues
or organs in a similar manner.
V
On the threshold of the world of living organisms stands that wonderful
minute body, the cell, the unit of life--a piece of self-regulating and
self-renewing mechanism that holds the key to all the myriads of living
forms that fill the world, from the amoeba up to man. For chemistry
to produce the cell is apparently as impossible as for it to produce a
bird's egg, or a living flower, or the heart and brain of man. The body
is a communal state made up of myriads of cells that all work together
to build up and keep going the human personality. There is the same
coöperation and division of labor that takes place in the civic state,
and in certain insect communities. As in the social and political
organism, thousands of the citizen cells die every day and new cells of
the same kind take their place. Or, it is like an army in battle being
constantly recruited--as fast as a soldier falls another takes his
place, till the whole army is changed, and yet remains the same. The
waste is greatest at the surface of the body through the skin, and
through the stomach and lungs. The worker cells, namely, the tissue
cells, like the worker bees in the hive, pass away the most rapidly;
then, according to Haeckel, there are certain constants, certain cells
that remain throughout life. "There is always a solid groundwork of
conservative cells, the descendants of which secure the further
regeneration." The traditions of the state are kept up by the
citizen-cells that remain, so that, though all is changed in time, the
genius of the state remains; the individuality of the man is not lost.
"The sense of personal identity is maintained across the flight of
molecules," just as it is maintained in the state or nation, by the
units that remain, and by the established order. There is an unwritten
constitution, a spirit that governs, like Maeterlinck's "spirit of the
hive." The traditions of the body are handed down from mother cell to
daughter cell, though just what that means in terms of physiology or
metabolism I do not know. But this we know--that you are you and I am I,
and that human life and personality can never be fully explained or
accounted for in terms of the material forces.