Part 11

Most all of these simpler sorts of ear are much like tiny rattles. There is a hollow ball lined with nerves. Inside the ball is a small hard ear-stone, or a number of smaller grains of ear-sand. When a sound comes along, (for a sound is nothing but jar), it shakes the rattle, so that the little stone inside bangs against the nerves. Then the animal hears. In the cod fish these ear-stones are unusually large, as large as the end of one’s thumb; children sometimes call them lucky-bones, and use them for playings. We also have these little rattles, two in each ear, with ear-sand. But these, which are all there is to the ears of lowly creatures, are only a small part of our hearing machinery.

You will find the ears of lobsters and crayfish, which are little fresh water lobsters, just at the point where the smaller feelers, which are double at the end, join the body. These, too, are merely ordinary ear-rattles; you can make out the opening on the upper side of the feeler. Of course, you know the ears of the frog—the big spots on the side of the head, back of the eyes. These spots are the drums of the ears; the real ear, much like our own, is inside. We have such a drum, only it is at the inner end of the hole into the ear, where it is much safer than it would be outside.

The fish’s ear you cannot find. That is inside; and the fish hears through the bones of his head, just as we do when we hold a stick in our teeth and tap the end, while we keep our ears stopped with our fingers. But the long dark stripe which you see on many sorts of fish, running from the place where the neck would be if fishes had one, the whole length of the body to the tail, and also forward across the head and around the eye, only you can’t make it out so well there, this also is a sort of ear. In fact, the ear itself is really a part of this “lateral line” very much improved—so much improved that we human beings and the four-footed beasts and the birds haven’t found it worth while to keep the lateral line at all. But the newts and salamanders still have it.

As for eyes, of these also there are all sorts. The star-fish has five, one at the end of each of its five arms, a tiny black dot. The jelly-fishes, some of the commoner sorts at least, have their eyes, such as they are, where the long tentacles join the center of the bell underneath. Some of the worms have several hundred eyes; some have a pair of eyes on each of the dozen or twenty joints of the body. The leeches, the common blood-suckers which get on our legs when we go swimming, have ten pairs of eyes, all on the front end.

Oysters, clams, and other “bivalves” have their eyes along the edge of the shell. Many of the snails have them on stalks, which they can pull back into the head or push out. The snail in Mother Goose, that

“...put out her horns Like a little Kylo cow”

and frightened the four-and-twenty tailors, was really only putting out her eyes to see these valiant heroes. Some of the shell-less snails, or slugs, besides the eyes on the ends of their horns, have a lot more, occasionally nearly a hundred, sprinkled over the back.

Such eyes, however, are really not good for much. They serve to tell light from darkness. They let the creature know when a shadow falls on him—which is usually the shadow of something on the point of eating him up, so he gets warning and bolts. We ourselves can do as much with our eyes shut tight; and that’s about all most eyes will do wide open. There are not many really good eyes, till you get the single pair of the animals with back bones.

Still there is one very fair sort of eye, though not nearly so good as ours, and that is the strange compound eye of the insects.

In general, the insects have either one, two, or three little eyes, at the front of their heads, which they use, probably, for seeing things close to them. Besides these, they have their two great compound eyes, often many times larger than all the rest of the head. The two together usually make almost a ball, and with them the bee or wasp or moth or dragon-fly sees clear round the horizon, above him and below him, all at once, and all equally well.

You know if you take a roll of paper, and look through it as if it were a telescope, you see a small bright spot at the end. If you had two such rolls, and could look through them both at once, you would see two such spots. If you had a thousand or more such paper tubes, and could look through all these at once, you would have something very like the compound eye of an insect.

Our eyes, as you know, are cameras. They form real pictures at the back, on the retina. But these compound eyes are not cameras, and they do not form any pictures anywhere. Instead, the insect looks out through one eye tube, and sees one spot of color; and through another, and sees another spot; and through a third, and sees another. Looking through some hundreds all at once, he sees a corresponding number of hundreds of spots.

But even ten thousand such spots would make no such sharp picture as we see in the small center of our field of vision where we see most clearly. Flies and ants and bugs and grasshoppers see only as we see things far round at the sides of our heads. They can see much farther round than we can; but they can’t see nearly so well anywhere.

So a fly never could see to read, even if he could ever learn. The page of letters and the white paper would simply mix to a gray blur. A fly cannot get through a netting with a half inch mesh, unless there is a light behind it. Altho the holes are many times larger than his body, he cannot tell hole from string well enough to fly through. If you try to put your whole hand on a fly, or hit him with one finger, you cannot do it. He sees something dark coming, and stands from under. But you can often get him by bringing down the whole hand slowly; and then, just as he is about to take flight, dropping one finger on his back. He can see the whole hand against the wall of the room; but he cannot see clearly one finger against the others.

So on the whole, the fly does not really see much with his little eye; in fact, taking, one thing with another, we boys and girls and men and women probably see more distinctly, and make more use of our eyesight, than any other creature that breathes.

XXXII

Having Senses and Using Them

All animals feel. So, too, do all plants. At least, all animals and plants sometimes move when they are touched. So they must feel. Whether they know that they feel or not, is another matter. Most likely, all plants and all the lowest animals, feel as we feel in our sleep, when we get tired of one position and turn over, or feel cold and pull up the bed clothes, without knowing at all what we are about. Somebody has said that the mind “sleeps in plants, dreams in animals, and wakes in man,” and that is really just about the state of affairs.

All animals except the very lowest also taste and smell. At least they choose their food, as they couldn’t very well do if they did not smell or taste it. Tho when you come to think of it, for an animal living in the water, taste and smell are all the same thing. The food is in the water, the creature’s mouth is full of water, and its nose (if it happens to have one, as most water creatures do not) is full of water also. So it doesn’t make much difference whether you say that the creature tastes the water or smells it.

Most animals have eyes and can see. Not a few also, which have not eyes, can still tell light from darkness. The earthworm, for example, has no eyes at all, yet it always avoids bright light, and keeps in its burrow when the sun is out. Neither has it ears, yet when it is part way out of its hole, it will at once pull back again when certain notes are sounded near it on a piano.

We might almost say that every bit of the life-jelly of which all living things are made has itself all the five senses. All of it seems to feel, and all in some faint way to see and hear, taste and smell, move and remember. Besides this, the life-jelly makes itself all sorts of eyes and ears, all sorts of mouths and noses, all sorts of muscles and brains, in order that it may see and hear, smell and taste, feel and move and remember better than it could do without them.

But all this time that we have been thinking about ants, and star-fish, and earthworms, we have been neglecting the creatures which we really care most about, and certainly know best, the cats and dogs and horses and rabbits and various pets of all sorts which we know by name, and which in return we believe are fond of us. These animals, the four-footed creatures with fur, and the birds, are of all living things most like ourselves. They are most like us in body, they are like us also in mind; and they have the same senses that we have—five, seven, ten, a dozen or more, according as we choose to count them.

They have, I say, the same senses that we have; but they use them differently. Nothing, I think, is more striking about dogs, for example, than the small use they make of their eyes. Often, indeed, they seem half blind; they fail to recognize their own masters ten yards away; get separated from them, and run round frantically, smelling of everything in range; while all the while, the master can see the dog perfectly well, and pick him out at a glance from a dozen others. One would think that the dog would simply look round, see his master, and join him.

I don’t think that they really are half blind. They probably can see nearly as well as we. They simply don’t use their eyes, and depend instead on their noses. Sight is the most important sense for us, as it seems to be for the birds. But the beasts seem to depend most on smell.

The tales we read about the scent of dogs, and especially of bloodhounds, are often almost beyond belief. The bloodhounds, I understand, are so-called, not because they are especially fierce, in fact they seem to be on the whole a rather gentle sort of dog, as dogs go, but because they are supposed to smell one’s blood, and to be able to follow the smell almost anywhere. I suppose they really do smell the perspiration; but they do it thru the sole of a heavy boot, when one has simply walked along over the ground; and they follow that inconceivably faint odor, hours after, and pick it out from all other smells, even those of other people cutting across the track.

Yet I sometimes think we make out the dog’s sense of smell to be more wonderful than it is. The same dog that tracks footprints so marvelously will nose round in all sorts of dirt as if he had no sense of smell at all, and eat things that we would not have in the house.

We also can do a little smelling. Anybody can smell the vapor of bromin in the air when there is one part in two hundred thousand. Hydrogen sulphid, which is the gas that makes the smell of rotten eggs, will scent up 1,700,000 times its bulk of air. The least little grain of musk will scent a room; as little as the fifty thousand millionth of an ounce can be smelled by a good nose. Tea and wine tasters (who of course are really tea and wine smellers) can pick out the place where grapes or leaves grew, and the season of the year. Wine tasters can tell one year’s vintage from another, and distinguish between the top and the bottom of a single bottle.

No dog, probably, can smell anything like such small quantities of these substances, or detect such minute differences. We smell musk and wine and tea; he smells footprints. One can’t say that either has a better nose than the other. Really, a good deal of the difference between us and the animals is that we depend on sight and hearing, because we can use these two senses to handle words. We can see words, and we can hear words; we cannot taste or smell them. So we get to relying on eyes and ears. But the animals, which don’t use words anyway, they think more about smells.

There is still another way in which we are apt, I think, to overestimate the senses of animals. We know, for example, that a horse will find his way home on a dark night, when everything is pitch black, and the driver cannot see his hand before his face. We say that the horse must have wonderful sight to make out his way under such conditions.

The real fact is, however, that the horse goes straight home thru darkness and storm, not because his eyesight is good, but because it is poor. He is at home in the night, because he does not see especially well by day. Those of you who have read _The Last Days of Pompeii_ (as everybody should, for it is a famous old story) will remember that when, during the eruption of Vesuvius, the city was darkened under the shower of ashes, so that the inhabitants wandered about in the streets completely lost and quite unable to find their way out, the blind girl was able to lead her friends straight to safety. She had always lived in the dark, and could find her way as well one time as another.

So it is with horses and other animals. They seem to see in the dark, when they really hear and smell. A horse especially depends for finding his way, on his muscular sense. While his driver is noticing houses and trees and sign-boards, the horse is noticing so long a pull up one hill, so much holding back down another, so much level stretch between. The man is lost when he cannot see his houses and sign-boards; but the horse’s hills and levels are still there.

You remember the rats that, when the passage in their maze was shortened, kept running full tilt against the end wall; and then when the passage was lengthened, kept turning too soon and butting into the side wall. The rats were depending on their muscular sense. They remembered their way as so long a straight run, then a turn. They could run as fast by night as by day, because they didn’t do much seeing either time.

We also depend on our muscular sense far more than we commonly realize. Doubtless we all know how to button our coats. But how do we know? We certainly do not know how it tastes, smells or sounds. I don’t think we often remember how it looks. What we do remember is the feeling of the buttons and the movements we make. But if we try buttoning with the other hand, or put on a coat that buttons on the other side, we feel as awkward as can be. We can see as well as before; the touch has not changed; there never was any taste, hearing, or smell. The difference is in the movements. The muscular sense is learning something new.

How hard it is to bat on the other side, to use any tool the other way round, or make any change which is strange to the muscular sense. That shows how much we all rely on it. If we play the piano, and remember pieces without the notes, it is by this muscular sense that we do it. Our fingers seem to know the tune; and in a sense, they really do. Surely, if a musician can find his way back and forth over the keyboard thru a long piece of music, by means of his muscular sense, it is not so remarkable that a horse should find its way home over the road, or a rat scamper thru its holes, guided by the same means. They don’t really see in the dark, they simply turn on another sense. We have it also; but mostly we trust to our eyes, instead.

There is another sense, too, on which animals are more given to depending than we are, and that is the sense of equilibrium and direction, which, as I have explained, has its seat in a part of the inner ear. You know the game where you are blindfolded, turn around three times, and then try to blow out a candle. If your direction-sense is at fault, as it generally is, you turn too far or not far enough, blow where the candle isn’t, and make everybody laugh. Men who have to find their way about over a wild country, explorers and the like, sometimes have this direction sense trained to a wonderful degree. They simply cannot get lost anywhere. The rest of us, who depend on street numbers and the sign-boards on the lamp posts, don’t have much use for this sense, and so never really learn to use it. Many animals depend on it a good deal. They find their way home in truly marvelous ways; and we say it is “instinct.” It really isn’t instinct, but just plain sight, hearing, smell, and direction sense. Men who have practiced their direction sense can find their way quite as well.

So in general, the animals haven’t different senses from ours, nor on the whole better ones. But they use them differently; and cultivate some senses which we let go to waste. For the most part, the animals depend on smell far more than we. Smell is apt to be their principal sense, as sight is ours. Because they don’t use their eyes as much as we do, they notice and remember more of what they learn thru their sense of direction and their muscular sense. But a man who tries hard can usually beat any animal at his own game.

The fact is, I suppose, that we, men and beasts and birds alike, have all the senses there are, all that any sort of creature could have anyway. Then each, according to his nature and habits, uses one more than the rest, to think and remember with.

XXXIII

Seeing In The Mind’s Eye

Not all us human beings use our eyes, ears, and noses in the same way, as a simple experiment will show.

Shut your eyes and think of the name of some familiar thing, like

BREAKFAST TABLE.

What did you see in your mind’s eye? Some people see that breakfast table just as clearly as if they were in the dining room with the table itself before them. They see the cloth and the plates and the food, the people at their places, the walls of the room, the furniture, all just as sharp and bright and natural as if they were looking at the things themselves. Others, more commonly, see the room and table dimly. They do indeed have an inner picture, but it is more like the picture one gets of things far round at the side of the head, out of the corner of the eye. They have a general impression, right as far as it goes; but they can’t see the patterns on the plates, nor the position of each fork and spoon. Still other persons, though there are not many of these, and children are almost never this way, cannot see any mental picture at all. They have no mind’s eye. They cannot see anything unless it is actually there.

People who can make such inner pictures are said to be eye-minded. Children are especially this way. Sometimes, indeed, they have difficulty in telling the difference between what they actually see, and what they dream or imagine. Then sometimes, they get punished for telling fibs.

Some people have this gift for making mental pictures to an extraordinary degree. If they have a lesson to learn, they see the page of the book before their inner eyes, and simply read off what it says. I knew of a type-setter in a printing office, who was a crack speller. He could spell anything. Give him a hard word, and he simply saw in his mind’s eye his composing stick with the word set up in type in it, upside down and backwards, as type is set by hand. Then he simply read off the letters, and always got it right.

Some musicians, as I have explained, remember their pieces as if in their fingers; but some see the inner picture of the notes, and read them off as if from a real score. There is a story of a public speaker, who in the midst of his speech stopped, hesitated, went back and said something different. He explained afterwards, that while he never read his speeches from a real manuscript, he did always read them from an imaginary one which he saw before his mind’s eye. This time, the manuscript that wasn’t there had some words written in between the lines, so that he could not read them easily.

Possibly you have heard of the truly wonderful performances of some champion chess players. Chess is played on a board like checkers, only it is a vastly more complicated game, with six different sorts of “men” all moved in different ways. Nevertheless, many players can play about as well when they do not see the board at all, as when they do. They make a mental picture of the board, sit blindfolded, and as the game goes on, they keep track of every move, as they are told what it is, by altering their inner picture. Some of the best chess players have played ten, fifteen, and even twenty different games, all at the same time, blindfolded, and won them all against as many separate players, each playing one game and looking at the board. Such a champion player has to carry in his head the picture of ten, fifteen, or twenty different boards, each with sixteen men, scattered about over sixty-four squares, and all continually changing. Yet they do this without ever making a mistake; just by these inner pictures in the mind’s eye.

Some eye-minded people can see a picture on a blank sheet of paper so clearly that they can mark over it with a pencil, and in this way make most accurate and effective drawings. Some can picture to themselves all four sides of a room at once, and imagine what is behind them as easily as what is in front. Some do not even hear directly what is said to them; but as each word is uttered, see the same word printed before their mind’s eye, and then read it off. There are those who say that they cannot wake up in the night and think of the bright sun, without having their eyes dazzled!

Now it is a great advantage to be eye-minded. There is no easier way of learning one’s lessons than by seeing books and maps and charts and diagrams, whenever you want them, right in front of your eyes, so that all you have to do is to look and see. The difference between boys and girls who get their lessons almost without effort, and those who get them only with the greatest labor, and then promptly forget them again, is often in just this power of making mental pictures. Some people can remember a page so clearly that they can actually read off the first or last words of each line, or read the printing backwards. Naturally, lessons come pretty easy to such lucky people.

Then too, to be eye-minded is a great source of happiness. One sees in the course of his lifetime, all sorts of beautiful and interesting things. If he can, whenever he wishes, recall these as mental pictures, almost as vivid as the reality, it is like seeing the reality all over again. He always has with him a collection of pictures, which though he cannot show to another, he can at any time enjoy for himself.