Part 18

Almost any of the senses can be fooled. Put your finger on you forehead; then move your head slowly from side to side so that the finger, held motionless, slides over the skin. Your muscular sense and your sense of equilibrium both testify that the head is moving and the finger is still. Yet you can’t make yourself believe it. It insists on feeling as if the head were still, and the finger moving.

Or try the senses of heat and cold. Take three dishes, one of hot water, one of cold, and one of a mixture of the two that shall feel neither warm nor cold but tepid. Put the fingers of one hand in the hot water, and the fingers of the other hand in the cold water. Keep them there a minute; then put them both in the tepid water. The tepid water will feel hot to one hand and cold to the other. Really it isn’t either. Perhaps, too, you have noticed, when you go in bathing, that as you wade in, you feel the cold only at the surface of the water where the skin was last wet. Hence the wisdom of going in all over at once with a header.

Even the sense of touch, in general the most reliable of the senses, can be deceived. When you are fishing and get a bite, where do you feel it? Most fisherman feel the bite at the end of the line, as if their nerves actually ran the length of the rod and down the string to the hook! And when a ball player cracks out a long hit, I leave it to all boys, if he doesn’t feel the place in the bat where it hits the ball. Or to take a commoner example, when you touch your hair, where do you feel the touch? In the hair itself where there is no feeling at all, or in the scalp where it really is? Or once more, if you hold the point of your nose between two fingers you feel one nose; but if you cross the fingers, and then touch your nose between the crossed parts, then you feel two noses.

Still on the whole, our senses are pretty reliable. The eleven different sorts of feeling spots in eye, tongue, and skin, that tell us about red, green, blue, heat, pressure, cold, pain, sweet, sour, bitter, or salt, and the ears and nose which we don’t know so much about, all these tell us, on the whole, the truth. Yet we never can be quite sure; so that wise people, and especially wise boys and girls, will beware of contradicting other people who chance to see, hear, taste, smell, feel or believe, a little differently from themselves.

XXIX

The Sight and Hearing Of Ants

So much then for our own senses, our sight, hearing, taste, pain, and the rest of the ten, or as many more as one thinks it worth while to count. The animals also have their senses, never apparently, more than ours, oftentimes fewer, sometimes very few indeed. So far as they have senses, these are like our own. But since some animals haven’t any eyes, yet can see—a little; and some haven’t any noses, yet can smell; and most of them haven’t any skins, yet can feel; one may easily guess that their seeing and smelling and feeling is not done quite in the same way that ours is.

I begin, then, with an animal that has eyes and can see, has no nose and can smell, and does its hearing with its legs. This animal is the ant. Of course, there are a great many different kinds of ants, as there are a great many different kinds of human beings, and these are by no means all alike. Some are black, some white, some yellow. Some are, for size, like the smallest letters on this page; some are more than an inch in length—and you can imagine their bite! Naturally also, sight and hearing, taste and smell, are not quite the same in them all.

Time would fail me to tell one half the strange ways of these interesting creatures, the most interesting creatures, probably, in all the world of little animals. Just as soon as you can, you must get hold of the books of Fabre, M’Cook, Sir John Lubbock, or Professor Wheeler, and read these strange things for yourselves—how the ants live in cities underground, have workmen and soldiers, carry on wars against their neighbors, raid their enemies’ nests and make slaves of the captives, have plant-lice for cows, and milk them of their sweet juice, and in return for this, feed and care for the plant-lice and their young, pasturing them on the roots of plants, and making no end of trouble for the farmers whose plants they are.

All this, I say, and many times more, no less fascinating, you can read for yourselves in the proper books, not only about ants, but about their cousins the wasps and bees as well. Just now, however, we are concerned with how much the ant knows, and how he manages to find it out.

Ants, in general, you must remember, live for the most part in total darkness under ground. The workers, to be sure, leave the nest in search of food, but the industries of the ant city, the storage of food, the care of eggs and young, and the building of the city itself, go on as if at the bottom of a mine. The queen ants, which lay all the eggs for the colony, and the male ants, who like the drone bees are gentlemen of leisure and don’t do much but loaf, are for most of their lives like the vine tendrils which I have already told you about. Whenever the light falls on them, they turn their heads down stream to the ray; and so if they move at all, they have to go toward the dark.

This, of course, holds them prisoners in the nest. But when at certain times of the year, a new brood of males and females appears, these ants, which, unlike the workers, have wings, suddenly become like the leaves and stems of plants; they have to head toward the light, and when they crawl or fly, they have to fly toward it. So when the rays of the sun happen to strike the nest, and light up the interior, out comes the swarm of winged males and females, leaving the wingless workers behind. Away they fly toward the sunlight; and those who are fortunate enough to find a suitable spot unhook their wings, settle down to found a new colony and a new nest. Thereupon, for the remainder of their lives, they turn their backs on the light like a tree root. The rest, however, die, after they have lost their wings, so that one sometimes finds great quantities of these scattered about after the swarming.

The workers, on the other hand, who have to be in and out of the nest about their business, do not have this tropism. They can take the light sidewise, or end on, or any other way, just as we can. The object of the tropism is to keep the males and females in the nest until swarming time, and then to get them out. Really, could there be invented a simpler or more effective way?

The worker ants can see. What is more, they can see colors. Nevertheless, they do not usually see quite the same colors that we see. For the most part they are red-blind, just as one man in thirty is. But unlike the color-blind human being, many ants make up for this red-blindness by seeing one or two other colors to which we are blind.

Of course, you know the colors of the rainbow, beginning with red at the bottom and running up thru orange, yellow, and green to blue at the end. You see the same colors also in a dew drop, or in the light which has come thru the corner of a square ink-well or the beveled corner of a mirror. These are the so-called primary colors, by mixing which all other colors can be made.

Now we, ourselves, do not all see the same rainbow colors. The great Sir Isaac Newton, who made a special study of rainbow colors and gave them their names, claimed to see seven—red, orange, yellow, green, blue, indigo, and violet. I myself can see only six; that is to say, I see only two colors beyond the green. More persons, apparently, see six than seven. Try it for yourselves and see how many you see.

The curious thing about the ants is that certain sorts, at least, see the rainbow colors as many of us do—green, blue, indigo, violet; and after that keep on still farther beyond this point, and see one or two more colors, which we never see, and for which, naturally, we have no names. Then, as I have said, to make it up, they are totally blind to red, and nearly blind to yellow. Some ants go even farther than this. They are totally blind not only to red and yellow, but to all the colors which we see. They do all their seeing by means of those two or more colors, farther out in the rainbow than the violet, to which we human beings are totally blind.

There is a considerable practical convenience in this. The worker ants, while they themselves run freely in and out of the nest, from darkness to light, usually try to keep their eggs and young in the dark. So when you turn over a stone and open into an ants’ nest, the most that you get is a glimpse of piles of white eggs or larvae, and a throng of workers skurrying about to drag them out of sight into the ground. You really can’t see anything at all of the regular daily life of the underground city.

But people who study ants simply carry them into a dark room, and look at them by red light. Since the ants cannot see red, they think they are still in total darkness, and so keep right on undisturbed with their work as usual.

Doubtless, it has already occurred to you, that in this particular the ant’s eye is very like a photographic camera. You who have cameras, open your plates and films by red light, because the sensitive chemicals are blind to red, and so treat red light as if it were darkness. You probably do not know, however, that it has now become the practice to take especially sharp pictures of small objects thru a microscope by means of some of these colors which the ants see and we do not. These colors do not come thru glass, and the instruments have to be made of quartz; but they take beautiful pictures in what seems to us total darkness, and what to an ant would seem some familiar color, about which we know nothing.

On the whole, then, certain ants at least rather have the advantage of us in seeing colors. We, on the other hand, more than make it up when it comes to hearing sounds.

We ourselves, however, differ in this a good deal from one another. Practically everybody who can hear at all, can hear all the notes of a piano, from the big growly end up to the little squeeky end. You young people can hear much shriller sounds than any on a piano; but we old codgers, whose ears are getting stiff, do not hear shrill sounds, even when we hear perfectly well those of lower pitch. The squeek of a mouse is about the limit for most people. Some can hear it, some can not. But cats can hear easily a mouse’s squeek, and much higher sounds besides, such as no human being can hear at all.

But the ants are still more inferior to us than we are to the cats. Some sorts which have been tested, can hear only two, and sometimes only one, octave above “middle C” on the piano, tho this is only half way up to the squeaky end of the key board. They hear well enough up to that point, and then are deaf to all sounds beyond.

Ants, moreover, do their hearing thru their legs. We ourselves, do something like this, when we grip one end of a stick in our teeth and scratch the other end with a pin. Even a lead pencil will do for the experiment; the sound is twice as loud when we shut our teeth on the wood and hear the scratching thru the bones of the jaw, as it is when we listen with our ears alone. Miss Helen Keller, completely blind and deaf, managed nevertheless to enjoy music by holding a music box in her hand, and feeling the jar; and she conversed in a telegraphic alphabet by tapping with her foot on the floor, taking the reply in the same way, by the jar, when anyone answers her.

The ants manage in much the same way. Stand an ant on cotton wool, and he is totally deaf to all sound. No sound, high pitched or low, can reach him thru the air. But put him on a hard surface, on his legs, and he hears thru his legs, taking the jar much as Miss Keller does. In fact, all sound is jar, either of air or of something else; a fact which you can easily prove for yourselves by striking a bell, and then touching a finger nail to the vibrating edge. Naturally we hear best with ears; but lacking these, any part of the body will make shift that can feel jars.

XXX

Ants’ Noses

Ants see, then, and hear. But their hearing is not at all good; while they do most of their work in pitch darkness underground, where they can not possibly see anything anyway. So they depend on touch, and still more on smell. Smell, therefore, is their chief sense, as sight is ours. So much thinking as they do, they do largely with their “smell center.”