Animal secrets told; a book of "whys,"

Front matter

■ I

A BOOK OF "WHYS"

BY

Contents

Chapter Page

I Eyes 1

II Xoses ,22

Chapter I Eyes

THE "FROXT-EYES" AXD THE " SIDE-EYES "

XE may wander through a Zoological garden with this subject of Eyes in mind and perhaps the very first thing to strike his attention will be the fact that many of the animals return his gaze from two eyes placed squarely in front like his own, while others can see him best with but one eye at a time, theirs being upon the sides of their heads. Practically all of the animals appear to be in one or the other of these two classes. He wonders Why. Then he notices that the Front-eyes are found in the various members of the Dog family, such as the fox and the wolf, in the lions, tigers, leopards and all other cats, bears and a variety of other animals; while the Side-eyes comprise a great list, running all the way from the towering giraffe to the tiny mouse, and including the Deer family, the Cow family, the Squirrel and Eabbit families and a multitude beside. It all looks accidental, for what has a giraffe in common with a mouse? And then perhaps he remembers some day having seen a cat intently watching a mousehole or a dog coursing a rabbit and realizes in a flash that an animal whose instinct it is to hunt for its food must have eyes placed for looking directly ahead, and at the same moment there comes the rest of the answer — the "Side-eyes" are the hunted creatures endowed with eyes which look in opposite directions to warn them of approaching danger. To the giraffe indeed, whose great size renders him particularly conspicuous, Nature has been especially kind in giving him large projecting eyes and grooving his skull behind them in such a way that he can actually catch a glimpse backward.

What could be more simple — Front-eyes and Side-eyes — the Hunters and the Hunted, through all variations of form and size? There are, it is true, exceptions, some of which will be noted under Birds, but among Mammals this rule seems to be nearly a general one.

EYES

THE CAT S EYE

Everyone knows the cat's eye, with its strange elliptical pupil, changing from a narrow vertical line in bright sunlight to a wide ellipse in the twilight.

The Contracted Pupils of the Cat

Probably most children have also asked the reason and been told that the pupil is in reality an opening which lets light into the back part of the eye, so that in the night time, when cats like best to seek their food, it must open widest to admit all of the faint light possible. Most children know something of this and yet probably few, even of their elders, appreciate the advantage of such an arrangement as fully as did the man who furnishes the following experience :

"I was being treated, " he said, "for a trouble in one of my eyes and had for several days to apply atropin to it. This atropin had the effect of greatly enlarging the pupil so that ordinary daylight became extremely painful to me and I was forced to keep my eye well bandaged. However, when I stepped into an unlighted room after nightfall the effect was interesting. Laying aside the bandage I found my doctored eye to be much more serviceable than the other one. Closing first one eye and then the other I would notice how the gloom, to my well eye, in which objects were barely discernible, became suddenly illuminated as soon as I tried its fellow pupil, and the furnishings of the room fairly started out of the darkness on all sides. I could realize as never before how a cat with its great pupils might go swiftly and surely where a man would only stumble and feel his way. My oculist also assured me that it was not uncommon for astronomers to treat their eyes with atropin during a total eclipse of the sun in order to observe more clearly."

Of course most animals have pupils which contract and expand to some extent, but the cat's advantage lies in the peculiar shape which makes

EYES 5

this possible to an extraordinary degree, not unlike the looping hack of curtains from the side until nearly the entire iris may be opened to gather in light rays. At the same time this wide opening would cause the animal blindness in sunlight did not nature provide for its automatic closing to a mere slit in the daytime.

The fox, also, that cunning night-raider of the dog family, unlike the rest of the canines, has this same contractile pupil, and so have some of the night reptiles, such as the alligator.

the owl's eye

Here, indeed, is an example of a night-seeing eye which is frequently nearly blind in the daytime. Compared with that of the hawk or the eagle the owl's eye is enormous and is fitted to gather in many more light rays, so that daylight with most varieties is too dazzling for comfort. Therefore the owl retires into some dark retreat at sunrise and waits'for the shadows of the next night to bring it both vision and food, since it feeds upon mice and other small animals which venture out in the darkness.

The owl is the only front-eyed bird. Remembering what has already been said this would indicate that it is a hunter. Still the owl is only one of many hunting birds, of which hawks and others have their eyes upon the sides of their heads. This seems a bit perplexing until we remember that the owl is the only night hunter among birds — the insect flight of nightjars and their kind being hardly to be classed as hunting. The daytime birds of prey sight their quarry from a height and need to command a wide range

The Front Eyes of the Owl

with their vision, while the owl wings noiselessly through forest darkness, peering into every place of concealment much as might a prowling fox and must have eyes so placed as to accomplish this use.

THE EAGLE'S EYE

Sometimes a man is spoken of as "eagle-eyed." Such a man generally has a bright eye and an

EYES 7

overhanging brow and whether he may have sharp sight or not he at least appears to have. This over-ridging of the eye is so noticeable in eagles themselves that it may well halt us to ask "Why"? The reason is not far to seek. One can see at a glance that because of it the eye is so set that it cannot look upward readily, but has a much better view beneath than the eye of

The Eagle's Downward Glaxce

the ordinary bird, and the rest of the answer comes on some summer day when one is out in the country and sees an eagle swinging in wide lazy curves so far above him that he seems a mere speck in the sky. It looks like the purest recreation and one cannot help envying him this mastery of the air. But to the eagle it is a matter of business — he is looking for his dinner. From the tremendous height he can scan miles of the earth's surface and with his telescopic eye sees objects which no man could distinguish without a powerful glass, so that the luckless squirrel, or rabbit, which is to satisfy his appetite is by no means overlooked. Hence it is that the eagle's interest lies all beneath him and the eye is so set as best to serve his needs. Moreover in scanning the distance the eye needs shade, and this, too, is accomplished by this same ridge, much as a person might hold his hand above his eye in looking afar.

In the eagle, as in other birds and some four-footed creatures, is found that curious, translucent third lid known as the "nictitating membrane," which passes over the eyeball with a shutter movement and cleans its surface from dust or other particles, without shutting out vision.

THE FKOG'S EYE

The frog is about as unlike the eagle as one thing can be unlike another and the contrast is especially great in their eyes. Instead of overridged eyes with a keen glance downward the big pop-eyes of the frog start from the very top of his head like the turrets in an old-fashioned monitor. This contrast is not surprising for they have a very different purpose to serve. In addition to looking for his own dinner the frog is forced to beware lest he himself serve as a meal for some one of the many creatures which

EYES 9

esteem him. The danger to such a low-squatting animal is likely to come from above and needs to be watched for.

There is another and important respect in which these elevated eyes are of great service — a purpose suggested by his life in the water. Squatting in some shallow place or hanging sus-

The Elevated Eye of the Erog pended in a quiet pond with little appearing above the surface save two very observant eyes, which bear a close resemblance to water bubbles, he is remarkably well concealed from the casual observer and not easily to be surprised.

The alertness of these eyes is well indicated in the words of Edwards, the Scotch naturalist, who describing the great noise made by frogs on a moonlight night, says: "Presently, when the whole of the vocalists had reached their highest notes, they became hushed in an instant. I was amazed at this and began to wonder at the sudden termination of the concert. But, looking about, I observed a brown owl drop down, with the silence of death, onto the top of a low dyke close by the orchestra. "

The unwieldy hippopotamus and the savage members of the crocodile and alligator tribe share this same peculiarity of elevated eyes, and like the frog enjoy submerging their bodies in the water while still able to keep a sharp lookout about them. Indeed one of the most interesting things about the comparative study of single features is to note how frequently animals which differ in almost every other respect may still have some feature characteristic in common, indicating one point of resemblance in their mode of life.

THE FISH'S EYE

The solemn fishes which peer at us through the glass fronts of their aquarium tanks, however dissimilar in size, form or color are pretty much alike in the expressionless stare of their large unwinking eyes. It need not occasion surprise that these eyes have such great pupils when one realizes how dim the light becomes on even the brightest day in penetrating the waters they

EYES live in. And as to expression, we are accustomed to speak of the eye as an "expressive feature," while any artist can tell us that the eye considered by itself has very little expression. It is the combination of lids and brow that gives the human eye its expression and how should the fish with practically neither lid nor brow have an expressive eye? In truth the fish has little

Lidless Eye of the Fish need of either. Our eyes being subject to injury from blows, scratches and even from dust must be carefully protected, but no dust can fly in the fish's world and the great cushion of water which surrounds it largely protects its eyes from accidents of other kinds. To give lids where lids are not needed would be contrary to the "Economy of Nature" and the fish must continue to wear its vacant stare, no matter what rudimentary impressions may be passing through its stolid brain.

One familiar group of fishes wear both of their eyes upon one side, but this fact is relieved of some of its strangeness when we learn that they are bottom-loving fish which habitually rest upon one side until the other becomes the top. Flounders, soles, halibut and other flat fish, though starting in life with the upright position of ordinary fish, begin to lie on one side as they grow older, until in time they lose their power of swimming back-uppermost and come to live entirely upon that side on the water 's bottom. And herein is a fact which indicates how wonderfully flexible is Nature in meeting changed conditions. The eyes which were at first placed opposite, as in the ordinary fish, undergo a change — or rather one of them does. The eye which would otherwise be kept against the bottom escapes that difficulty by traveling slowly around the head until it rests beside its fellow on the top.

In the waters of Brazil is found the " Double- Eye' ' a small fish with the strangest of all fisheyes. Lengthwise across the center of this eye is a line which divides it into two sections, and these two sections have lenses of entirely different character, as in "bifocal" spectacles where the upper part is made for seeing at a distance

EYES 13

and the lower for reading. In the eye of this fish the upper lens is lenticular (i. e. like two joined watch crystals) and the other of the spherical type. The mystery appears to deepen when we learn that the lenticular lens is similar to that of land animals while the spherical type is that of fishes which must see through the dense medium of water; and yet herein lies the explanation, for these curious creatures frequently swim with just half an eye projecting above the surface, and this upper half eye looking through air must needs differ from that which stays in the water.

Down in the black waters of Mammoth Cave, Kentucky, on the other hand, dwells a fish with no eyes whatever. In a place where not the faintest ray of light is ever seen, save from human visitors' torches, eyes would be entirely useless and Nature has accordingly dispensed with them.

THE SNAKE'S EYE

Here is another lidless eye, and one for which mankind feels an almost universal abhorrence. These beautiful creatures — for in spite of prejudice they are almost universally beautiful, with much richness of marking and an unapproachable grace — have nevertheless a glittering, stony istare which brings an instant repulsion. A snake with eyes softened by eyelids would be no longer the snake of our childhood's terrors. Still, the snake is in no wise responsible for its lack of lids, and would indeed find them an embarrassment when it came to shedding its skin, for we must not attribute this lack to the same cause as marks it in the fishes. A snake does not have its eyes protected by water, on the contrary it has special reason to need protection going as it does "upon its belly all the days of its life," but in this case it carries before its eye a clear, horny plate attached to the skin, which is like a window to look through.

If one think of a diver's suit and helmet with wearer he will get some idea of this skin-shedding process, to be more fully discussed in another chapter, for the eye-plate goes with the rest of the covering. One will frequently hear mountain dwellers speak of the especial danger from rattlesnakes in the shedding season when they are practically blind and will strike on suspicion at everything near them. This is due to the fact that shortly before losing the skin a gummy, milky secretion begins to form just under the eye-plate, in time hardening and clearing into a new plate like the one which is being lost. It renders the snake virtually blind for a short time, during which its instinct of self-defense renders it particularly savage and suspicious.

"8 © §

EYES 15

THE FLY'S EYE

The baffling skill with which a fly evades a sudden blow becomes less mysterious when one examines the relatively huge "eyes" which cover so much of its head. If one will use a powerful magnifying glass he will see that the surface of these eyes is composed of a mosaic-like pattern of honeycomb effect, and, as it is generally known, each of the tiny sections is the lens of a separate eye. In other words these two large patches are really eye-clusters.

In the light of what modern science has shown us of flies as conveyers of disease, it is undoubtedly a righteous act to crush one of these little nuisances, if one can catch it, but think, after all, of this sudden destruction of a creature bearing 8,000 separate eyes pointed in 8,000 separate directions ! It is perhaps small wonder that it so frequently escapes.

These compound eyes are true lenses as is shown by an interesting experiment with the microscope, when a portion of the cornea of a fly i is mounted in such a way as to cover a photographically minute picture or bit of printing. Looked at through the microscope this object may be seen refracted by each individual lens.

Such compound eyes are very common in the insect world and some of them are much more elaborate than those of the house-fly, the dragon fly possessing some 13,000 in its clusters. Their owners cannot roll their eyes, nor readily turn their heads, but then how little need with such a battery to rely upon !

THE SNAIL'S EYE

So slow that it has passed into a proverb, and a most persistent " house-holder " even when forced to move, the snail is curious in several respects, not the least of which is the interesting way in which it wears its eyes. These eyes are too simple and primitive to deserve

The Snail Raising its Eyes

much notice here, were they not thrust up into our attention by being mounted on a pair of stalk-like processes which it is able to push upward from its head.

This arrangement has its advantages to the snail as anyone who has ever climbed a tree to get a better view will realize. Most animals have legs or wings to raise them from the ground,

EYES or have at least the power to raise their heads like caterpillars, but the humble snail can only elevate its eyes to get its view, and this may at times be most important because of the bulky shell which must be carried through many tangled obstructions. It would be hard to imagine another device so effective.

THE HUMAN EYE

Passing over a number of animal eye-forms there is one which is undoubtedly more wonderful than any other in nature and that is the eye which reads these words. Have you ever ex-

The Loxg Human Eye amined your eye with a mirror and a question combined? If not you will find it interesting. Notice how long it is in comparison with the rounded eye of the dog or the cat. Why? Roll your eyes and see. Man is front-eyed, for he is not onlv the most successful hunter in the animal kingdom but he has many higher rises for a focused gaze. On the other hand man's body is naturally defenseless compared with most creatures, neither swift to escape danger nor strong to repel it, and with no natural weapons worth speaking of. Consequently he may also be classed among the hunted animals, which, as already seen, are generally side-eyed.

These long, narrow front-eyes of ours also command a very considerable side view, and a slight movement well around to one side will catch "the tail of the eye" in an instant. It is impossible to say how often lives must have been saved by this side-eyed action.

Compared with man there is very little eye-motion among most of the animals which are forced instead to move their heads in looking. This eye-motion is so necessary in focusing, that is, in bringing both eyes to bear upon the same point whether it be near or far, and focusing is so useful in giving us our ideas of relief and perspective, that this difference alone shows the higher capacity of man's perception and the higher requirements it serves.

For example, shut one eye and then reach out to touch some neighboring object. You will find yourself curiously unable to determine its distance, since all vision looks flat when seen with a single eye.

Another illustration is that of the difference

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between an ordinary flat photograph and the wonderful sense of distances obtained from stereoscopic views, where two slightly different images are blended together by the glasses. Man's ideas of the relations of surrounding objects must therefore be much clearer than those of other creatures.

There is a point which may be mentioned in passing, although one cannot learn this from the mirror but must take instead the word of the oculist, viz., that there is a small circular spot upon the retina, or back wall of the human eye, which is the only spot capable of receiving absolutely true impressions. This is found in no mammals save the order of Primates which includes man, the apes and the monkeys, and it follows that the sight of lower animals, however well adapted to their own purposes must be somewhat defective judged by human stand-

| ards.

Eeturning to our mirror inspection, supplemented by experience, the protection of the

} human eye is hardly less wonderful than its powers. "What of those arches that we call eyebrows, what is their office? Not merely beauty, we may be sure, beautiful as they often are. It is easy to solve the problem, on any warm day when the perspiration forms upon the forehead, rolls down the vertical, smooth surface — so different from the hairy, sloping animal face — and then is deflected by those admirable arrangements of smooth lying hairs to a point beyond the angle of the eye. If an occasional smarting drop should enter through carelessness of position, it but emphasizes our indebtedness to the brows for the many they lead safely by.

And then the lids, not only do they exclude the light when we wish to sleep, or modify it when it is too strong, but they must be constantly on guard against dust and other flying particles, closing automatically, "quick as a wink," and fringed with other hairs curved outward for the same beneficent purpose. Let an occasional bit of dust slip by the defense, however, and see how quickly the lachrymal glands flood the eye with tears to wash the intrusive particle into the nose passage or over the rim of the lower lid.

Finally the eye must be protected from blows, must have a shelter in proportion to its great value, while still left in the exposed position from which alone it could be of any service. This is accomplished most beautifully by placing it in a socket formed by the bridge of the nose and the bones of the brow, cheek and temple, which so guard it that one can press a lead pencil across the average eye, either from top to bottom or from right to left, without particular discomfort, while the eye-ball is additionally so cushioned as to suffer ordinary blows and survive.

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All of which, without going at all into the technical side of optics, forms such abundant scope for our observation that we may well close a brief survey of Eyes in Animals with some of the plainer characteristics found in those of the head of the kingdom.

Chapter II

SK any three people what noses are for and two of the three will probably answer "to breathe with/' and let it go at that. The third, after a moment's thought, may add * ' and to smell with." Ask again, "What other uses has the nose beside breathing and smelling?" and now all three have no answer ; it is your turn. You continue, i ' The nose is also a probe, a plow, a club, a hand, an arm, a pump, a hose, a blow-pipe and a feeler!" By this time the first two have decided that you must be crazy- — always the easiest judgment upon the unusual — but the third begins to look interested, for he thinks he detects a bit of method in your madness. He wants to know ' ' Why. ' ' For answer we shall examine a variety of Noses, in all their strange unlikeness, -to see whether we can discover some of Nature's reasons for making them to differ so greatly.

"froxt nostrils" axd "side nostrils"

At the very outset, as in "Eyes," we meet with an interesting fact which might hardly be noticed were we considering the animals entire, instead of just their Noses. It is this: nearly all of the mammals divide into two great classes, viz., those having flat-tipped noses with both nostrils squarely in front and close together, and those having slanting nostrils running well around to the sides of the muzzle. A little examination reveals that this division is strongly marked, and when we come upon anything strongly marked in the realm of Nature, it is an invitation to ask "Why."

We look again. Which are the animals hav-

I ing Front-nostrils? The Dog family of course,

, including the wolves and foxes, and all of the Cat

tribe, little and big, from old "Tortoise-shell" in

i the kitchen to the tiger in the jungle, as well as

I riously enough these seem to be practically the

| same animals as the "Front-eyed" Hunters of

; the last chapter. But even so, why should they

have Front-nostrils?

As we stand for a moment perplexed a dog ' brings us our answer. He comes trotting along, his nose close to the ground, and, without hesitation, bends his course to the right or left as though tracing over some invisible chart by means of his power of scent. It is natural for him to do this. He has a nose especially fitted for it: that flat tip and those two openings squarely in front, where they can be brought to bear upon the same spot of ground in concen-

The Front Nostrils of the Wolf trated attention in order to pick up the delicate trace which human nostrils could not perceive.

The dog is a natural meat eater, therefore must be a Hunter when not supported by man, and that wonderful nose is perhaps the most important part of his entire outfit. It helps him to find his prey. And the wolf, fox, tiger, lion, mink, weasel and other "Front-nostrils" are Hunters, too, and hence are also specialists in ground scent, as is shown by their noses.

But as there are Hunters there must also be the Hunted, and these are found in that other great division, the "Side-nostrils," eaters of vegetation, not flesh. These are keen-scented creatures too; but their interest is less in knowing what animals have passed before than in detecting those which may possibly be approaching, and this information comes to them on the wind from the most remarkable distances, as every hunter knows. Hence their nostrils run around to* the sides where they can read the message of each passing breeze and receive warning of the coming danger.

"Jake," a guide in the deer country of Canada, was talking indignantly of the foolish ways of would-be hunters from the city. "Only yesterday," he said, "I was watching a fine buck, across a lake fully three-quarters of a mile wide. He was playing about on the other shore when <all of a sudden I noticed him lift his head, and sniff with his nose out in my direction. The mext moment he was off as hard as he could ^jump. I was sure he could not see either /of us from where he stood, but when I looked around to the other chap I understood why the buck had jumped. The crazyheacl had lighted a cigar so quietly that I never heard him, though he was close to me. The deer smelt it, though nearly a mile away. ' '

Jake also objected to the scented toilet soap which his companion used, to the perfumed vase-

The Doe's Side Nostrils

line with which he anointed his gun, and especially to the top-boots which he wore, soaked with tallow as a protection from moisture. These last, he insisted, must be exchanged for, his own spare pair of deerskin moccasins. "You see,"

he explained, "they are Indian-tanned by smoke, and the scent of wood smoke doesn't tell a deer that man is coming his way. Yes," he continned, "it's a wonderful thing, is a deer's nose. Xow just look at this foot. See, just above the hoof on the leg there is a little cleft between the parts of the leg bone, just about as big as you could put the tip of the blade of a dinner knife into. That is where the deer carries its musk, the old hunters say. It is not a very powerful perfume, is it? Yet a deer will know its mate, or the sex of another deer, by the scent, far away, long before he can see its form. I've proved that many a time.

" I believe that you will never get very near to deer of any kind if you have their blood upon your clothes. The Indian women have for generations done all the skinning and bleeding of the game. And the reason is not, as some missionaries think, because they are an uncivilized lot, but it's a case of self-preservation. The women know that it is necessary in order to get food, that the hunter should not be tainted so that he would not be able to catch up to the deer. ' '

THE BLOODHOUND'S NOSE

We should expect to find that the bloodhound with his long, full muzzle, and broad, flat nostrils, had well developed powers of scent, and indeed he is the most famous of all the trailers. The greyhound, on the other hand, has also a long muzzle but its tip is narrow and pointed, and his scent correspondingly so much weaker that he hunts by sight and is sometimes known as the ' i gaze-hound. ' '