the head above the left ear. One man, a musician, finds that while
he can hear music as before, he hears it only as noise, and no
longer recognizes it as tunes. He has been hit low down on the side
over the spot where he keeps his music memory. Another, hurt a
little higher up, can hear noises as before, but cannot tell a
factory whistle from a church bell. Not that they sound alike; but
he has forgotten which is which. Occasionally, a watch-maker,
engraver, or other skilled artisan, will get an injury well up on
the side of his head at the place from which he manages his right
hand. Then he loses all his special skill of hand. He can still use
his right hand for ordinary acts, dressing, eating, shoveling coal;
but the power of doing thinking-things is gone. He has become like a
day laborer who has never learned a skilled trade.
There is a strange case of a business man who got a blood clot just
over his word-thinking spot, but toward the upper side so that while
it ruined his speech center and the place where he kept his memory
for the look of printed words, his memory for the sound of words
escaped. He could neither read nor write, nor speak a word; but he
could understand what was said to him. Curiously enough, he could
handle figures as well as ever, for the figure-remembering spot and
the figure-writing spot had escaped. So for seven years this man
kept on with his business. Every letter had to be read to him; and
all he could do in answer was to write down figures and point to
them. Meanwhile, he took lessons most diligently, trying to learn to
write and speak with the other side of his brain. But it was no use.
There was also a learned man, who in addition to his native
language, which was English, knew Greek, Latin, and French, and
could besides read music. After his accident, he could read his
native English only with the greatest difficulty, about like a child
of six or eight who can make out easy words, slowly; while writing,
he could scarcely read at all. French, he could read much better; as
well, say, as a high school graduate. Latin he could handle pretty
well; about like a boy just out of college. But Greek and music he
could read and write exactly as well as he ever could. The accident,
which had pretty well spoiled the place where he remembered his
native language, had only damaged the spot where he remembered his
French, had hardly touched the place where he remembered his Latin,
and had missed entirely the place where he kept his memory of music
and Greek.
You understand, of course, that when one of these very same
accidents occurs to a left-handed person, no matter how much it
damages his head on the left side, it does not destroy his speech or
memory. Or if the same thing happens to a right-handed person, on
the right side of the head, his speech and memory do not suffer. The
hurt has to be on the thinking side in order to affect the thinking.
When little children are hurt in these ways, at first they suffer
loss of speech or memory just as men and women do. But little
children, as I have already explained, are not hard and set like
grown up people. They can start over again, and learn to think,
speak, and remember with the other halves of their brains. But as
soon as any one gets too old and stiff to learn anything new, then
he is too old to learn an old thing over again on the other side.
Do you see now why you have to go to school five hours a day, and
sit on a hard seat studying still harder lessons, when you would
much rather sneak off and go in swimming? It is so that you may
build up these thinking spots in your brains. We are born with
brains like the animals, alike on both sides. Only slowly,
painfully, with much hard and disagreeable work, that we had a great
deal rather not do, do we manufacture a one-sided human brain. We
begin young, while the brain is still growing. With years and years
of work and study, we slowly form the thinking spots over our left
ears, which we are to use the rest of our days. When we are grown
up, we can no more form new thinking places on one side of our
heads, than we can form new thinking places on the other side, after
the old ones have been destroyed. The business man who lost his
ability to read, never learned to read again, tho he worked at it
six years, harder than any child ever studied. If he had put off
learning to read till his old age, he could never have learned at
all.
It does seem a long time that we sit on a piano stool doing our
daily practicing, and mighty little fun. Let us then remember that
all the while, we are making a time, tune, and harmony remembering
place just back of the left temple, and tying it up with the spot
farther up on the side of head from which we manage our hands and
fingers. It is slow work; but when once we get the job done, we
shall be able to enjoy and remember music with it for the rest of
our lives—forty, fifty, sixty years. Surely, this is cheap enough at
the price of a little daily practicing.
It really is a good deal as if we were born like a dog or a horse,
with head, body, and legs, but no hands, and had to make our hands
for ourselves. How we should work in such a case, building our
fingers, shaping our thumbs, and in every way getting the best
possible sort of hands to use thereafter. And what should we think
of any careless child who left off a finger or two, or was too lazy
to put on a proper thumb, and so had to be deformed and crippled all
the rest of his life.
But the thing which makes us different from dogs and horses, isn’t
half so much our hands, as it is the spot of brain substance which
we build for ourselves over our left ears. This spot looks like the
corresponding spot on the other side. But somehow or other, nobody
knows just how, our work and study and trying hard make that
particular patch more important for us than anything else in our
whole bodies. If we fail to build good thinking spots while we are
young, we shall be deformed and crippled for the rest of our lives.
XXI
Where Some Of The Animals Do Their Thinking
It really is a great advantage to us to bring all our thinking into
one small spot, where everything is handy to everything else. It is,
in fact, almost like the convenient little kitchens they have on
railway dining cars, where the cook can reach every dish and pan and
kettle, cupboard, stove, refrigerator, coal-bin, pantry, china
closet, and all, without shifting his feet or hardly even turning
round. If you want to understand how great this advantage is,
consider the case of some animals who not only have no words to
think with, but in addition, do their remembering and thinking, such
little as they do, at several different places or all over their
bodies.
There, for example, is the sea-anemone, such as one finds at the sea
side, in the salt water pools, after the tide has gone out.
Beautiful creatures they are, set solidly on thick muscular bodies,
and pushing out their long pink or yellow tentacles, a dozen or
twenty of them, sometimes, like the petals of a daisy. Only you must
be careful not to alarm this animal flower. If you do, sometimes if
you so much as let your shadow fall across him, in an instant he
will pull in those pretty tentacle-petals, and turn to a lump of
tough jelly, almost as hard, and not much more interesting, than
half a rubber ball; and there you will have to sit and wait and wait
for something to happen, only it never does, until somebody makes
you come in and change your shoes.
[Illustration: A sea-anemone.]
However, if you are careful, you can begin to feed this animal
flower with bits of meat or fish. Drop a morsel cautiously on one of
the tentacles, and he will reach out with the tentacles near by and
roll the food slowly over and over, until finally, with much
difficulty, he will get it into the center of the disk where his
mouth is. Then he will slowly open his mouth and work it in. In
short, the tentacles are the sea-anemone’s hands and fingers; but he
feeds himself clumsily enough, and cannot make any movement quickly
or certainly, except shutting up when he is frightened.
If you think you can fool the little animal by feeding him with
pieces of shell, or wood, or pebbles, or anything that is not food,
you will soon find out that he is wiser than he looks. These things,
which he cannot eat, he simply lets fall off his tentacles to the
ground. But real food he will eat and eat and eat, till he swells up
and up and up, and you think he is going to burst, only he never
does; and in time, if you do not get tired feeding him first, he
will take the food more and more slowly, and finally will refuse it
altogether.
Now if instead of feeding the sea-anemone with pieces of meat, you
press the meat against blotting paper so that the paper soaks up the
juice, and then feed the creature, sometimes with real meat,
sometimes with blotting paper and meat taste, at first he will
swallow both with equal avidity, not knowing apparently the
difference. After a half dozen trials, however, he will begin to
take in the blotting paper somewhat less rapidly than the meat. He
will continue to take the paper with more and more hesitation until
after some twenty trials or so, while he swallows the meat as
before, he will refuse to take the paper at all. He has learned the
difference.
All this time, you must have taken pains to offer the real food or
the imitation to the same tentacle, so that the same fingers shall
have stuffed the morsel into the mouth. If now, after the polyp has
thoroly learned the difference between meat and paper, on one side
of his mouth, you try feeding him in the same way on the other side,
you will discover that the new side knows nothing whatever about
what has been happening on the other. The anemone which has learned
to take meat and leave paper on one half of his body, still takes
them both on the other half, and it will take just as long to teach
the difference to the second side as it has already taken to teach
it to the first.
The reason for this peculiar behavior is simple. The sea-anemone,
instead of doing the remembering for his whole body, all in one
spot, as we do, spreads it out over a ring of brain which circles
the mouth, between the mouth and the base of the tentacles. He does
the remembering for each tentacle close to the base of the tentacle
itself. Each therefore remembers something of what has happened to
itself, something less of what has happened to its next neighbor,
still less of those beyond, and almost nothing at all of what has
happened to the tentacles clear over on the other side, a whole inch
away.
Even that much remembering, however, the tentacle-brain does not do
especially well. After the animal has learned his paper-meat lesson
thoroly one day, and can tell the difference straight off every
time, the next day he has as thoroly forgotten it. If he learns it
once more on the second day, he will as completely have unlearned it
again on the third, and will swallow paper and meat with equal zest.
So much then for animals who do their thinking in rings instead of
in spots. Now we shall see what happens to a creature who tries to
do his thinking all over his body.
I have already mentioned the infusoria which swarm by the thousands
in the water of ditches and puddles. They are decidedly small
animals, the largest of them no bigger than a pin head; and as I
explained before, they are remarkable in that each infusorian is
just one single cell. Most of them are free-swimming, that is, they
go about as they like thru the water as a fish does; but some grow
on stalks like flowers, tho even these can usually let go their
anchorage and float away to a new station.
[Illustration: More common infusorians, much enlarged.]
Small as they are, they feed on still smaller plants, the bacteria.
Nevertheless, they do not know their food either by sight, hearing,
taste, or smell. One hungry infusorian, looking about in search of
his dinner, will pass right by a mass of bacteria large enough to
feed him the rest of his life and not notice it. He will swim so
close as almost to graze the feeding ground, yet keep straight along
without turning or pausing, as if it were not there. The next
instant, he may run against some small particle which isn’t good to
eat at all, and swallow it down forthwith. In fact, the infusorian
simply swallows whatever happens to hit his mouth. If this happens
to be good to eat, why so much the better. If it happens to be only
a grain of dust or a fleck of shell, down it goes just the same; the
infusorian doesn’t know the difference.
When the infusorian, swimming straight ahead, runs into some
obstacle too large to swallow, it stops, backs off, turns a little
to one side, and goes ahead again. But he never takes any pains to
turn toward the side which will do the most good, or to notice
whether he turns enough to do any good at all. He is just as likely,
having run against the extreme end of some object, to turn exactly
the wrong way, so that he hits it next time fairly in the middle.
Then he backs off once more, turns again, and swims ahead. Perhaps
this takes him by; perhaps he butts the obstruction again at the
spot where he struck it first. Then he tries again, and yet again,
and in the course of time, usually manages to get by.
So the infusorian is a funny little machine, made so that when it
hits anything it backs off, turns somewhat, and goes ahead again. If
one is very clever with his fingers, as men who study creatures such
as these have to be, one can take a slender needle and touch the
infusorian on the front end—we cannot call it the head. Thereupon he
stops, backs, turns, and goes ahead. Touch him on his side. Again he
stops backs, turns, and goes ahead. Prick him from behind. Once
more, he stops, backs—right on to the needle which is pricking
him—turns, and goes ahead. Try heating the water. As soon as the
infusorian feels uncomfortably warm, he stops, backs, turns, goes
ahead. Try cooling it. The same process. Add to the water something
that the creature notices, acid for example. Still the same old
stop, back, turn, go ahead; tho often the next go-ahead sends him
straight into the drop of acid and burns him up.
So far as we can see, therefore, everything that the infusorian
feels at all, feels to him exactly like everything else. No matter
what it is he feels, nor on what part of his body he feels it, he
always acts in precisely the same way. It is, moreover, doubtful
whether one of these animals ever learns or remembers much of
anything, or in any other way ever finds out how to do anything
which he could not do about as well the first instant of his life.
XXII
What Plants Know
Of course, the plants do not really _know_ anything. Still they
usually act wisely; and that is practically just as good as knowing,
and often looks very much like it.
For instance, one sees little pine trees growing in a pasture. Each
year they send up a “leading shoot” a foot or more long, straight up
into the air, to become by and by the main trunk. Each year, also
from the point where the trunk ended the year before, there starts
out a whorl of little branches, a half dozen or so of them, some of
which will by and by become the main limbs. It is the same way with
the firs and spruces. If you haven’t seen these growing out of
doors, you have at least had them for Christmas trees in the house.
When these little trees grow in the pasture, pretty soon a cow comes
along and eats off the top so that there is no longer any leading
shoot to grow up into a trunk. What does the tree do then, but pick
out one of the side branches from the uppermost whorl, and turn that
up into a new leading shoot. So the tree gets a trunk in spite of
the cow. Somehow or other, nobody understands how, one of those
green tufts which was meant to grow into a horizontal branch,
changes its mind, turns up, and becomes the vertical trunk.
This may happen five or six times to a single tree—for when it isn’t
cows, then it’s wind, or insects, or something else, that kills the
bud that ought to grow up into the main trunk. So one finds often in
the woods, trunks of evergreen trees that grow up straight for a few
feet; then take a sharp turn to one side, and another straight run
of trunk; then another turn. Each of these turns means that
something has happened to the leading shoot, and that the tree, like
a very wise vegetable, has at once made another leading shoot out of
a side branch. But still the curve remains to show where the branch
had to change its mind.
It certainly is most clever of the tree. I for one, should like much
to know how that side branch finds out that something has happened
to the leader, and that it must step into the gap; and how the tree
decides which side branch it shall be that is to make the change.
Sometimes, indeed, the tree doesn’t seem to be able to decide, so
that two branches turn up instead of one; and after that, the tree
has a double trunk. Sometimes, too, when the leading shoot is weak
but still alive, a side branch turns up; and if the leader recovers
itself and grows up strongly again, there will be here also a double
trunk; but in such a case, one trunk will grow up straight, while
the other starts out with a turn. So the tree sometimes makes a
mistake, just as we all do. But it almost never makes so bad a
mistake as to have three branches turn up into trunks, tho as far as
numbers go, it might have six.
Another matter that all plants seem to understand is the difference
between up and down. At least they never make the mistake of sending
their roots into the air and their stems down. You recall the bean
plant that is inside the bean, with its little root and its tiny
stem and leaves tucked snugly away between the two big seed-leaves
which are most of the bean. You may plant the bean any way you like,
right side up or wrong side up, point the stem up and the root down,
or the stem down and the root up, put the bean flat on its side,
even plant it in one position for a while and then dig it up and
turn it over to another. It makes no difference what you do; that
little stem will twist round and grow up, and the little root will
twist round the other way and grow down, tho each has to travel half
way round the bean to do it. Somehow every seedling does tell which
from t’other.
Now the question is, does the plant grow up because up is up, or
because up is toward the light? The matter is easily settled. If we
plant a seed in a pot, pack the earth in solidly, put a screen over
the surface to keep the earth from falling out, and then tip the pot
upside down then if the stem wants to grow up it will have to grow
away from the light, and if it wants to grow toward the light it
will have to grow down. Thus we shall find out whether the plant
goes by light-and-darkness or by up-and-downness.
As a matter of fact, while nearly all plants are influenced by both,
for young seedlings just getting their start in the world, the
question of up and down is much the more important. So a seed
planted in an upside down pot, will grow its stem up into the dirt,
and its roots downward into the air.
So a plant knows in a way, up from down, as indeed it must, else a
tree would not be able to send a tall trunk straight up into the
air. Besides, when a tree happens to get uprooted, and yet lives,
the new part of the trunk which grows after the accident, does not
continue the direction of the old fallen portion, but turns and
grows straight up. You can see this sort of thing almost anywhere in
the woods.
The plant also, in a way, knows which way the light is falling on
it. Commonly, as everybody is supposed to know, the plant grows
toward the light. Yet the curious thing about it is that some parts
of some plants always grow away from the light. The leafless runners
of the strawberry geranium grow away from the light; but when they
begin to form leaves on their ends, then they change and grow toward
the light like other plants. The tendrils of many vines also, always
grow away from the light, while the leaves and, stems are growing
toward it. The reason is that by turning away from the light, they
turn back toward the rock or tree trunk or wall or trellis which
gives them support.
Thus the plant, that seems to know two things, is twice as well off
as the infusorian that knows only one.
XXIII
What Plants Can Do
As trees and vines and shrubs and bushes are wiser than they look,
so they can do more than we commonly suppose. We think of all plants
as merely sitting still and growing; but they really do much more.
Most ponds and ditches, the water squeezed out of bog moss, even
damp spots on rocks or the ground, often swarm with minute green
plants, that swim about quite as freely as if they were animals.
Some of these, single-celled, pear-shaped affairs, have two long
tails at the smaller end, with which they lash the water and so get
about as freely as do the equally small animals which live with
them. In fact, some of these little plants are so much like some of
the infusoria, which I have already told you about, that about the
only way to tell them apart is by the green color of the
vegetable—tho to be sure the plant is apt to have two tails, while
the animal has only one.
Then there are the so-called “diatoms” which live, absolutely
millions upon millions, in the slippery coating which covers the
sand and stones at the bottom of streams and ponds. These are
commonly counted among plants; but they have two shells like an
oyster and swim about freely—as an oyster does not, for all it is an
animal. Then too, there are the “slime moulds,” which at some times
of the year look like common puff-balls, and at other times change
into a soft jelly, and crawl away to find a new place to change back
into a puff-ball again.
In short, there is simply no end to the animal-like actions of the
simpler plants, for after all, plants and animals are a good deal
alike. To be sure, you don’t have any difficulty in telling a cow
from an apple tree, but that is because a cow is a very complex sort
of animal, and an apple tree is a very complex sort of plant. But
the simpler plants, which have neither stem nor twigs nor leaves nor
roots nor branches, and the simpler animals, which have neither
heads nor legs nor bones nor muscles nor skins, are naturally not
nearly so different from one another as apple trees and cows. And
when you come to the very smallest and simplest creatures, the
distinction between the two seems hardly worth counting. Some
animals grow on stalks, and some plants swim about or crawl. Many
plants are not even green; a few animals are. Once in a while, you
find the very same creature described as an animal in one book, and
as a plant in another.
However, I began to tell you about the animal-like actions of the
plants which we see more commonly, the ordinary trees and shrubs and
bushes, grass and house plants and the like.
We say that plants grow toward the light. They really do much more
than that. When a houseplant has stood for some time at a window, in
the same position, every leaf, as you know, is set to face the
light, so that as much sunshine as possible falls on the upper
surface of each. But if you turn the pot round, so that the leaves
face away from the light, within a day or two, every several leaf
will have skewed itself round toward the window again. So the plant
can move its leaves about as much as an animal can move its head;
only it moves very much more slowly. But the sunflower, grown out of
doors, can wag its head fast enough to keep up with the sun. Indeed,
it is called the sunflower, not so much because its blossom looks
like the sun, as because, in the morning at sunrise, it bends its
tip over toward the east so that the rising sun shall strike the
upper sides of its leaves, follows the sun around thru the sky all
day, and in the evening finds itself with all its upper leaves
facing west. Then in the night it nods back again ready for the next
sunrise.
Many leaves, if you notice them closely, have a soft bunch or
cushion, either where the blade of the leaf joins the stem or where
the stem of the leaf joins the branch or sometimes at both places.
This is the joint on which the leaf does its turning. The clover,
which is an especially active little plant has one of these joints
for each of its three leaflets.
[Illustration: The leaf has a special joint on which to turn.]
Not only the leaves of a plant, but the tendrils also, and the soft
green parts of the stem, and the slender tips of the roots, turn and
twist slowly, moving like the limbs of a very sluggish animal. Did
you ever wonder how the climbing vines, the beans, peas, morning
glories, woodbines, and the like, manage to find the poles and
trellises on which they grow? The seedling comes out of the ground
six inches or a foot away from the nearest support. Next thing you
know, it has grown straight for the support and begun to climb.