Part 1

Chapter 14,379 wordsPublic domain

THE CHILDREN’S LIBRARY

NATURAL WONDERS

THE CHILDREN’S LIBRARY

NATURAL WONDERS

EDWIN TENNEY BREWSTER

Garden City — New York

DOUBLEDAY, DORAN & COMPANY, INC.

1928

PRINTED IN THE UNITED STATES AT

THE COUNTRY LIFE PRESS, GARDEN CITY, N. Y.

PREFACE

No small part of our fundamental knowledge concerning the world of nature has been put into shape for comprehension by children, time out of mind. “The Swiss Family Robinson” is half natural history, even if not always of an especially convincing kind; and science of all sorts, good and bad together, makes up no small portion of Jules Verne’s uncounted tales. “Cousin Cramchild’s Conversations,” if there had been such a book, would have embodied the Victorian idea of what every child should know about his universe; while of actual books, we elders recall at once Abbott’s “Science for the Young,” and the half dozen contributions to juvenile knowledge of John Trowbridge and “Arabella Buckley.” Even the great Ostwald, within the decade, has made a child’s book on chemistry after the old conversational form.

In school, moreover, between his geography and his nature study, the modern child becomes acquainted with not a little modern science, while in most of our states a detailed acquaintance, by no means always scientific, with his own physiology is required by law of every public school pupil. One thing with another, today’s child of eight or ten is supposed to know a little of physics and of biology, together with a good deal in a general way of earth science and the elements of human physiology.

Naturally, there are excellent texts and reading books in all these fields. So far as I am aware, however, the present work is the first attempt to set before young readers some knowledge of certain loosely related but very modern topics, commonly grouped together under the name, General Physiology. It is, in short, an attempt to lead children of eight or ten, first to ask and then to answer, the question: What have I in common with other living things, and how do I differ from them? Incidentally, in addition, I have attempted to provide a foundation on which a perplexed but serious-minded parent can himself base an answer to several puzzling questions which all children ask—most especially to that most difficult of them all: By what process of becoming did I myself finally appear in this world?

How far I have succeeded with either task, I leave to the mothers who shall read this book aloud.

E. T. B.

Andover, Massachusetts

NATURAL WONDERS

CONTENTS

Chap. I — How The Chicken Gets Inside The Egg Chap. II — Some Other Sorts of Eggs Chap. III — Little Fishes in The Brook Chap. IV — Of Plants’ Eggs Chap. V — What Little Boys And Girls Are Made Of Chap. VI — More About Living Bricks Chap. VII — How Much Of Us Is Alive Chap. VIII — How We Grow Chap. IX — How We Grow Up Chap. X — How We Grow Old Chap. XI — Why We Grow At All Chap. XII — Things That Do Not Have To Be Learned Chap. XIII — Why We Like Certain Things Chap. XIV — Animals’ Games Chap. XV — Some Instincts Of Chicks And Kittens Chap. XVI — Certain Stupidities Of Animals Chap. XVII — How We Differ From The Animals Chap. XVIII — Something More About Speech And Thinking Chap. XIX — Why Most Of Us Are Right-Handed Chap. XX — Where We Do Our Thinking Chap. XXI — Where Some Of The Animals Do Their Thinking Chap. XXII — What Plants Know Chap. XXIII — What Plants Can Do Chap. XXIV — Some Plant-Like Doings Of Animals Chap. XXV — The Five Senses And The Other Five Chap. XXVI — Eyes Chap. XXVII — Seeing And Believing Chap. XXVIII — Some Other Senses Chap. XXIX — The Sight And Hearing Of Ants Chap. XXX — Ants’ Noses Chap. XXXI — Some Other Eyes And Ears Chap. XXXII — Having Senses And Using Them Chap. XXXIII — Seeing In The Mind’s Eye Chap. XXXIV — Ear Minds And Others Chap. XXXV — Living Automobiles Chap. XXXVI — Air And Fuel Chap. XXXVII — Men In Glass Boxes Chap. XXXVIII — Of Sugar And Other Poisons Chap. XXXIX — Snake Venoms And Others Chap. XL — Of Measles And Rusty Nails Chap. XLI — The Great War Chap. XLII — More About The Great War Chap. XLIII — Living Apothecary Shops Chap. XLIV — What Becomes Of The Tadpoles Chap. XLV — Nature’s Repair Shop Chap. XLVI — Little Monsters Chap. XLVII — How The Animals Keep Their Tools Sharp Chap. XLVIII — Why The Blood Is Salt Chap. XLIX — Horses’ Fingers Chap. L — How The Elephant Got His Trunk Chap. LI — Something Nobody Understands

ILLUSTRATIONS

Frontispiece

The Robin Moth

Full Page Illustrations

How the Chicken Gets Inside the Egg

Seeds That Have Plumes and Wings

The Star-fish Has Eyes on His Arms; The Slug Also Has Eyes on His Horns; The Snail Has Eyes on His Two Longer Horns

Lymph Cells or White Blood Corpuscles

Extinct Reptiles Which Look Like a Mixture of Alligator, Rhinoceros and Kangaroo but Their Bones Were More Like the Bones of Birds

In the Text

A Sea-Urchin

Eggs of Perch After Egg Laying

Salmon with Yolk Sac

The Bean Egg Changes to a Bean Plant

Living Bricks Which Make the Skin of a Leaf

Cells of the Inner Tree Pulp

Cells of the Outer Skin of a Leaf

Cells of a Pond Scum Much Enlarged

Three Sorts of Infusoria Much Enlarged

Some Jelly-fish Grown on Stalks and Some Swim About in the Sea

The Cob Is the Mother of the Corn

Pollen Grains Much Enlarged

A Right-handed Person Has All His Thinking Spots on the Left Side of His Brain

A Sea-anemone

More Common Infusorians, Much Enlarged

The Leaf Has a Spiral Joint on Which to Turn

Optical Illusions

Ear of a Mole Cricket on the Front Leg

Back of the Frog’s Eyes Are the Ear Drums

A Newt

The Leaves Take in Air Through Breathing Holes

In Place of Lungs, Insects Have Breathing Holes

The Minute Animal Which Causes the “Sleeping Sickness”

The Caterpillar Changes into a Moth

Accidents to Growing Fish Eggs

A Two-headed Turtle, a Crab with an Eye on One Side and a Feeler on the Other, and a Child With Two Great Toes on Each Foot

The Fangs of a Rattlesnake

Early Man Scratched Pictures of the Mammoth on Pieces of Its Own Bones

The Elephant Has Lost the Front of His Face

Our Single-toed Horse Has Been Made Over from a Four-toed One

How the Chicken Gets Inside the Egg

There is no more fascinating sight to be seen anywhere than an incubator full of eggs just as the chickens begin to hatch out. You look through the little glass window in the side and see, at first, only rows of clean white eggs, dozens upon dozens of them, looking as if they were all ready to go into the family ice-chest or to be made into omelets for breakfast.

But they are not. First you begin to hear faint scratchy sounds. Pretty soon, here and there, a hole breaks through the broad end of an egg, and a tiny bill sticks out. The little chick is packed so tightly into the egg that it can move only its head. So it pecks and pecks; and stops to rest; and pecks again; and the hole in the shell gets larger and larger; until by and by, the egg cracks open, and a brand-new chicken draws its first long breath and looks out into the world.

After that, the chick usually takes a long rest, for it is pretty tired. When it feels better, it begins to move its legs and wings, and a half-hour or more after it first began work, it gets clear of the shell and stands up on wabbly legs, wet, bedraggled, weary, as disconsolate looking a little object as can well be imagined. Shortly, however, the feathers, which at first were plastered tight to the skin, dry off and fluff out, the legs get steady, and soon there is running about a rolypoly yellow chick, seemingly at least twice as large as the egg which held him only an hour before. Truly it is a wonderful sight, five hundred eggs turning into little chicks in an incubator, for all the world like the kernels of corn changing to pop-corn in the popper.

But wonderful as it is to see the way a chick comes out of an egg, it is still more wonderful to see the way it gets in. A fresh, new-laid egg has no chick inside. After it has been kept warm three weeks, it has—all ready to come out. The question is how the chicken got there.

Many different men have studied this question. For the most part, they have started a dozen or more eggs at once, and then taken them one by one and two or three hours apart, and cautiously broken them open to see what was inside. Sometimes, however, a student of eggs carefully cuts away the shell on one side, until he has made a hole about the size of a ten-cent piece. Over this he cements a sheet of glass as thin as paper, so that he can look through this tiny window into the egg, and see the chick grow.

This is really easier than it sounds. The yolk, as everyone must have noticed in hard-boiled eggs, does not stay in the middle of the egg, but always floats to the upper side. The chick, too, always forms on the upper side of the yolk; and when the egg gets turned over, the yolk rolls round like a barrel in the water and brings the chick to the upper side. So the chick, until it grows big enough to be a tight fit, always lies crosswise of the egg, on the upper side of the yolk just under the shell.

At first, of course, there is no chick at all, but only a round white fleck hardly larger than the head of a large pin, on the side of the yolk where the chick is by and by going to be. Before the end of the first day after the egg is laid, this little fleck has become somewhat oval in outline and an eighth of an inch across. Through its center runs a whiter line, as thick as heavy basting cotton and a sixteenth of an inch long; about half as large, that is, as an “l” or a figure “1” in the type on this page.

This is the beginning of the chick. Only it has hardly yet begun to be a chick, for it has as yet neither head, tail, wings, legs, eyes, nose, mouth, heart, stomach, brain, nor any other parts. It is in short, only a tiny line of chicken substance, which is now to begin to be made into a chicken.

Early in the second day of incubation, the little white line begins to get thicker on the end where the head is going to be. The brain and spinal cord appear first; later in the day there is the first sign of eyes and ears. At about the same time, the heart begins to form, and the minute blood vessels to grow out into the yolk like the first roots of a tiny plant. Before the end of the second day, the heart has begun to beat, and the blood vessels have begun to absorb the yolk to feed the growing chick. The yolk, in its turn, feeds on the white; for as everybody knows, the yolk and the white of an egg are stored up food, on which the little bird can live and grow until it is old enough to get out of the egg and shift for itself.

At the beginning of the third day, or a few hours before, the chick, which has been lying on the yolk face down (only it hasn’t any face yet), turns over on its left side. It is getting to be a big bird now, a quarter of an inch long and as thick as a good sized pin. Next, the brain grows rapidly; and so do the eyes, though these are not so large as the eyes of the finest needles. Now too, the nerves begin to form; also the lungs, the stomach, liver, and other organs of digestion; and there are beginnings of a tail, though without feathers.

During the fourth day, there are signs of a mouth. Legs and wings, looking just alike, begin to bud out from the body. Another day, and one can tell which is which; while now there appear beginnings of the skull and of the place where the back bone is going to be. Meantime, the little bird has become more than a half-inch long—though it does not yet look the least bit like a bird, but more like a large “?” mark. There is still no front to the body, and the heart, beating merrily away, hangs out in the yolk.

With the second week, the little chicken does begin to look something like a real bird. The bones begin to harden; while on the tip of what has been just an ordinary nose appears a speck of chalk, which will by and by harden into a bill. The claws begin to grow; and there are signs of feathers, each one still enclosed in the little transparent sac in which it forms.

At the end of two weeks, the white of the egg is all used up; and the little bird, which has been lying crosswise of the egg, now turns to bring its head toward the broad end. The yolk, too, is getting small; and on the nineteenth day, the chick pulls the last remnant into its little tummy, and begins to close over the hole. At about the same time also, he pecks through into the large air space which one sees in the broad end of an egg, when he eats it, hard-boiled, at a picnic. For a week or more, he has been breathing by means of a sort of gill, much like that of a fish, only that instead of being on the side of the head like a fish’s it grows out from the middle of the stomach on a long stalk and spreads over the inside of the shell. So the chick breathes through the shell, which is full of minute holes almost too small to be seen. But after the last bit of yolk has been taken in, this gill shrivels up and drops off, and the chick breathes with its lungs like the rest of us.

At the end of three weeks, there is nothing left of the egg but the shell and a tea-spoonful of water. The chick, which began life the size of a pin head, now fills the shell jam full, with only just room enough to peck the hole that lets him out. On the twenty-first day of his imprisonment, out he comes.

Some Other Sorts of Eggs

All birds lay eggs. Some are brown or white like the hen’s egg; some are green, some buff, some blue; many are speckled. Some, like the eggs of the screech owl, are almost as round as marbles; not a few are so pointed at one end as to be fairly pear-shaped. The hummingbird’s egg is the size of one’s finger tip, the ostrich egg is as large as one’s head. But all alike they have shell and yolk and white; and by and by, a little bird inside. Only sometimes, like the chick, the little bird hatches out with feathers grown, and only needs to dry off and get its breath, before it is ready to run about and pick up a living for itself; and sometimes, like the little robin, it has no feathers, cannot stand up on its legs, and has to be fed by its parents, like a human baby.

Snakes and turtles have eggs also, very much like birds’ eggs. Like these, they have white and yolk; and the little reptile grows in the egg almost exactly like the little bird. For curiously enough the turtles, snakes, lizards and crocodiles, tho they look so very different from birds, are really very like them. They all have large eggs, with large yolks; and the little animal begins at a point in the side of the yolk, and does not, for a long time, fill the entire egg.

Oddly enough, there does not seem to be much connection between the size of an animal and the size of its egg. Big birds, to be sure, have big eggs; and little birds have little eggs. But a great crocodile, fifteen or twenty feet long and able to bite a man in halves, is hatched from an egg no larger than that of a goose. The little salt water minnow, or killifish, which is only as long as one’s finger, has very large eggs, for a fish, almost as large as small blue berries, and quite as large as the eggs of salmon and trout which grow to be a hundred times heavier. But cod fish, which sometimes are almost as large as a man, and the great sturgeons, which are as long as three men and as heavy as a horse, have eggs not much larger than the periods on this page, smaller even than those of a tiny ant. As for the little sea creatures, star-fish, sea-urchins, and the like (which to be sure, are quite as large as a hummingbird or a wren) their eggs are but fine dust, which cloud the water and are too small to be seen at all.

However, the smaller the eggs, the more of them there are, to make up. While some birds lay only two eggs at a time, and few more than a dozen, some fishes lay a hundred or more, the cod a hundred thousand, and the sturgeon two or three million.

Sometimes, when one is poking about in the brooks in the spring of the year—as every boy and girl should do, for it is great fun—one happens upon masses of transparent jelly half as large as one’s head, full of tiny black dots. These black dots, which are just about the size of the o’s in this book, are the eggs of frogs. If instead of being in round masses, they are in long strings, a yard sometimes in length, then they are almost always the eggs of toads; but if they occur neither in masses nor in strings, but separately, then they are the eggs of newts.

It seems strange that a frog should be able to lay a mass of eggs and jelly forty or fifty times larger than the frog itself. The real egg, however, is only the dark speck; and this when it is first laid has only a thin coating of jelly, hardly thicker than paper and nearly dry. As soon, however, as it touches the water, this dry jelly begins to swell, and goes on swelling and swelling for three hours until it is a hundred times larger than it was to start with.

These balls of frog’s eggs look, then, very much like tiny hens’ eggs with black yolks, broken into a bowl ready for cooking. They really are not quite this; because the frog’s eggs have no shell and no white, being simply yolk and nothing else. In fact, the only sorts of eggs that do have white are those of birds and reptiles; while few others have shells either. The jelly of frog’s eggs is not “white,” because it is not meant for the little frog to eat, but to keep other creatures from eating him. Besides this, it helps to keep the little chap warm.

You will recall that the little chick begins as a tiny dot on one side of the yolk, and keeps growing larger and larger until it uses up both yolk and white and fills the entire shell. Not so the little frog. Always, from the very beginning, it is as large as the egg. It is the egg, in fact. You can see that the egg is dark above and light below just as the tadpole will be, and the frog after him. At first, however, the baby tadpole does not have any parts or members. He gets in proper succession, eyes, ears, backbone, brain, skin, tail, and the rest; but he does not grow any larger until he hatches out, wriggles his way thru the jelly, and begins to eat.

At first the tadpoles are very tiny, only a quarter of an inch in length; and they cling in tufts to the under side of the water plants. After that, I suppose, everybody knows what happens.

There is still another curious difference between hens’ eggs and frogs’. When a frog lays an egg, that egg is nothing else but just egg—the little frog has not begun at all to form inside it. But when a hen lays an egg, while there is no little creature in that either, still the egg has already begun to get ready to turn into a chick. Some animals go farther than this, so that when their eggs are laid, the little creature is already formed inside, and so has only the last part of his growing left to be done outside. Certain fishes, certain reptiles, and various other animals besides, actually put off laying the eggs until so late that the young is all ready for hatching. Such eggs are laid and hatched at the same time, or even hatched first and laid afterwards.

All the four-footed creatures which have fur and hair, horses, cattle, dogs, cats, monkeys, and the like, manage in this way. And because this kind of egg doesn’t get knocked about, it does not need to have either hard shell nor thick jelly to protect it, but only a thin skin. For this reason, and because the egg hatches a few moments before it is laid, people are apt to miss it entirely, and so to get the idea that these animals have no eggs at all. But they have—one egg for each little animal.

We pretend that the bunny rabbits at Easter are hatched from the colored Easter eggs. They really are hatched out of rabbits’ eggs. No one notices the remnants of the rabbits’ egg, because what little there is soon dries up to almost nothing, or else the old mother rabbit eats it. Besides, one has all one can do to look at the new bunnies. Nevertheless, all little animals come out of eggs, puppies, colts, lambs, calves, kittens, every kind of living creature that is big enough for you to see, and a good many besides that are so small that you have to look for them with a microscope.

III

Little Fishes In The Brook

Of all eggs, the most interesting, I think, are the fishes’. Nearly all of these are pretty small, little round whitish globules like sugar pills. Some, like the eggs of trout and salmon which one finds in the gravel banks of rapid streams, are as large as fair-sized beads. Many, like the eggs of sea fish which float near the surface of the ocean, would go thru the eye of a darning needle.

The point, however, which makes them especially interesting is that so many of them are like tiny glass marbles. The membrane around them is so clear, and the substance of the egg itself so transparent, that with a magnifying glass, one can look right thru the egg, and see the little white fleck inside grow from nothing at all to a real fish, long enough to reach clear round the egg and lie with its tail almost in its mouth.

Some eggs are much clearer than others. The clearest are, at first, like clear glass, so that they can not be seen at all under water. Soon, however, a tiny vague white spot begins to form on the lower side. Then one can make out that the egg is covered with a rather thick membrane, that within this is a narrow, clear space filled with water, while within this and still smaller, floats the tiny yolk which is the real egg that is going to become the little fish.

The white spot on the yolk is not itself fish, but only fish stuff, which is being made ready to turn into fish by and by. The spot grows larger and thicker, until it looks like a round dab of putty stuck on the side of a marble. When this cap has grown until it is about half as much in diameter as the egg itself, it thins in the middle and thickens at the edges, until it forms a ring. A very strange thing, thereupon, happens to this ring. It begins to grow; and as it grows, it keeps slipping farther and farther round the egg. Soon it has become a band round the middle of the egg. Then as it moves along still farther to the other side of the egg, it has, of course, to grow smaller in order to fit. So it does, and the extra length taken in at one point in the ring, forms the body of the little fish. The head has already begun to form from a thickening at one side of the ring before it passed the middle of the egg. The two sides of the ring form the two halves of the body. But the tail being easier to make, does not grow out until much later.

Now there is a head and a body; but the only difference is that the head is bigger. Neither has any parts. There are no eyes, ears, nose, or mouth in one; nor any fins, backbone, stomach, nor scales in the other. These all appear later, much as in the chick—eyes, ears, brain, and heart early; fins and tail, scales and the whole front of the body not until long afterwards.