Popular Science Monthly/Volume 18/November 1880/The Profusion of Life
I WONDER whether it ever occurs to most people to consider how brimful our world is of life, and what a different place it would be if no living thing had ever been upon it? From the time we are born till we die, there is scarcely a waking moment of our lives in which our eyes do not rest either upon some living thing or upon things which have once been alive. Even in our rooms, the wood of our furniture and our doors could never have been if life did not exist; the paper on our walls, the carpet on our floors, the clothes on our back, the cloth upon the table, are all made of materials which life has produced for us; nay, the very marble of our mantel-piece is the work of once living animals, and is composed of their broken shells. The air we breathe is full of invisible germs of life; nor need we leave the town and go to the country in search of other living beings than man. There is scarcely a street or alley where, if it be neglected for a time, some blade of grass or struggling weed does not make its appearance, pushing its way through chinks in the pavement or the mortar in the wall; no spot from which we can not see some insect creeping, or flying, or spinning its web, so long as the hand of man does not destroy it.
And when we go into the quiet country, leaving man and his works behind, how actively we find life employed! Covering every inch of the ground with tiny plants, rearing tall trees in the forest, filling the stagnant pools full of eager, restless beings; anywhere, everywhere, life is at work. Look at the little water-beetles skimming on the surface of the shady wayside pool, watch the water-snails feeding on the muddy bank, notice the newts putting their heads above water to take breath, and then remember that besides these and innumerable other water animals visible to the naked eye, the fairy-shrimp and the water flea, and other minute animals, are probably darting through the water, or floating lazily near its surface, while the very scum which is blown in ridges toward one corner of the pool is made up of microscopic animals and plants.
Then, as we pass over plain, and valley, and mountain, we find things creeping innumerable, both great and small, hidden in the moss or the thick grass, rolled up in the leaves, boring into the stems and trunks of trees, eating their way underground or into even the strongest rock. The lion, the tiger, and the elephant, roaming over Asia, Africa, and India, rule a world of their own where man counts for very little. Even in our own thickly peopled country hares and rabbits multiply by thousands in their burrows, and come to frolic in the dusk of evening when all is still. The field-mice, land and water rats, squirrels, weasels, and badgers, have their houses above and below ground, while insects are to be found everywhere, testifying to the abundance of life. Not content, moreover, with filling the water and covering the land, this same silent power peoples the atmosphere, where tiny bats, butterflies, bees, and winged insects of all forms and shapes and colors, fight their way through the ocean of air, while birds, large and small, sail among its invisible waves.
And by and by we reach the sea, and there we find masses of tangled seaweed, the plants of the salt water, while all along the shores myriads of living creatures are left by the receding tide. In the rocky pools we find active life busily at work. Thousands of tiny acorn shells, scarcely larger than the head of a good-sized pin, cover the rocks and fling out their thread-like arms in search of food. Small crabs scramble along, or swim across the pools, sand-skippers dart through the water, feeding on the delicate green seaweed, which in its turn is covered with minute shells not visible to the naked eye, and yet each containing a living being.
Anywhere, everywhere, creatures are to be found, and even if we sail away over the deep silent ocean and seek what is in its depths, there again we find abundance of life, from the large fish and other monsters which glide noiselessly along, lords of the ocean, down to the jelly-masses floating on the surface, and the banks of rocky coral built by drops of living slime in the midst of the dashing waves. There is no spot on the surface of the earth, in the depths of the ocean, or in the lower currents of the air, which is not filled with life whenever and wherever there is room. The one great law which all living beings obey is to "increase, multiply, and replenish the earth"; there has been no halting in this work from the day when first into our planet from the bosom of the great Creator was breathed the breath of life, the invisible mother ever taking shape in her children.
No matter whether there is room for more living forms or not, still they are launched into the world. The little seed, which will be stifled by other plants before it can put forth its leaves, nevertheless thrusts its tiny root into-the ground and tries to send a feeble shoot upward. Thousands and millions of insects are born into the world every moment which can never live, because there is not food enough for all. If there were only one single plant in the whole world to-day, and it produced fifty seeds in a year, and could multiply unchecked, its descendants would cover the whole globe in nine years. But, since other plants prevent it from spreading, thousands and thousands of its seeds and young plants must be formed only to perish. In the same way one pair of birds having four young ones each year, would, if all their children and descendants lived and multiplied, produce two thousand million in fifteen years, but, since there is not room for them, all but a very few must die.
What can be the use of this terrible overcrowding in our little world? Why does this irresistible living breath go on so madly, urging one little being after another into existence? Would it not be better if only enough were born to have plenty of room and to live comfortably?
Wait a while before you decide, and think what every creature needs to keep it alive. Plants, it is true, can live on water and air, but animals can not; and, if there were not myriads of plants to spare in the world, there would not be enough for food. Then consider again how many animals live upon each other. If worms, snails, and insects were not over-abundant, how would the birds live? Upon what would lions and tigers and wolves feed if other animals were not plentiful, while, on the other hand, if a great number of larger animals did not die and decay, what would the flesh-feeding snails and maggots and other insects find to eat? And so we see that for this reason alone there is some excuse for the over-abundance of creatures which life thrusts into the world.
But there is something deeper than this to consider. If in a large school every boy had a prize at the end of the half year, whether he had worked or not, do you think all the boys would work as hard as they do or learn as well? If every man had all he required and could live comfortably, and bring up his children to enjoy life without working for it, do you think people would take such trouble to learn trades and professions, and to improve themselves so as to be more able than others? Would they work hard day and night to make new inventions, or discover new lands, and found fresh colonies, or be in any way so useful or learn so much as they do now?
No, it is the struggle for life and the necessity for work which make people invent and plan, and improve themselves and things around them. And so it is also with plants and animals: life has to educate all her children, and she does it by giving the prize of success, of health, and strength, and enjoyment to those who can best fight the battle of existence, and do their work best in the world.
Every plant and every animal which is born upon the earth has to get its own food and earn its own livelihood, and to protect itself from the attacks of others. Would the spider toil so industriously to spin her web if food came to her without any exertion on her part? Would the caddis-worm have learned to build a tube of sand and shells to protect its soft body, or the oyster to take lime from the sea-water to form a strong shell for its home, if they had no enemies to struggle against and needed no protection? Would the bird have learned to build her nest or the beaver his house if there were no need for their industry?
But as it is, since the whole world is teeming with life, and countless numbers of seeds and eggs and young beginnings of creatures are only waiting for the chance to fill any vacant nook or corner, every living thing must learn to do its best and to find the place where it is most useful, and least likely to be destroyed by others. And so it comes to pass that the whole planet is used to the best advantage, and life teaches her children to get all the good out of it that they can.
If the ocean and the rivers be full, then some must learn to live on the land, and so we have, for example, water-snails and land-snails, and whereas the one kind can only breathe by gills in the water, the other breathes by means of lungs in the air, while between these are some, such as the river-snails of the tropics, which have both gills and lungs, and can breathe in both water and air. We have large whales sailing as monarchs of the oceans, and walruses and seals fishing in its depths for their food, while all other animals of their kind live on the land.
Then, again, while many creatures love the bright light, others take advantage of the dark corners where room is left for them to live. You can not lift a stone by the seaside but what you will find some living thing under it, nor turn up a spadeful of earth without disturbing some little creature which is content to find its home and its food in the dark ground. Nay, many animals for whom there is no chance of life on the earth, in the water, or in the air, find a refuge in the bodies of other animals and feed on them.
But in order that all these creatures may live, each in its different way, they must have their own particular tools to work with, and weapons with which to defend themselves. Now, all the tools and weapons of an animal grow upon its body. It works and fights with its teeth, its claws, its tail, its sting, or its feelers; or it constructs cunning traps by means of material which it sucks out of the water, as in the case of the oyster, or gives out from its own body, like the spider. It hides from its enemies by having a shape or color like the rocks or the leaves, the grass or the water, in which it lives. It provides for its young ones either by getting food for them, or by putting them, even before they come out of the egg, into places where their food is ready for them as soon as they are born.
So that the whole life of an animal depends upon the way in which its body is made; and it will lead quite a different existence according to the different ' tools with which life provides it, and the instincts which a long education has been teaching to its ancestors for ages past. It will have its own peculiar struggles and difficulties and successes and enjoyments, according to the kind of bodily powers which it possesses, and the study of these helps us to understand its manner of existence.
And now, since we live in the world with all these numerous companions, which lead, many of them, such curious lives, trying, like ourselves, to make the best of their short time here, is it not worth while to learn something about them? May we not gain some useful hints by watching their contrivances, sympathizing with their difficulties, and studying their history? And, above all, shall we not have something more to love and to care for when we have made acquaintance with some of life's other children besides ourselves?
The one great difficulty, however, in our way, is how to make acquaintance with such a vast multitude. Most of us have read anecdotes about one animal or another, but this does not give us any clew to the history of the whole animal world; and, without some such clew, the few observations we can make for ourselves are very unsatisfactory. On the other hand, most people will confess that books on zoölogy, where accounts are given of the structure of different classes of animals, though very necessary, are rather dull, and do not seem to help us much toward understanding and loving these our fellow creatures.
What we most want to learn is something of the lives of the different classes of animals, so that when we see some creature running away from us in the woods, or swimming in a pond, or darting through the air, or creeping on the ground, we may have an idea what its object is in life—how it is enjoying itself, what food it is seeking, or from what enemy it is flying.
And, fortunately for us, there are an order and arrangement in this immense multitude, and in the same way as we can read and understand the history of different nations which form the great human family spread over the earth, and enter into their feelings and their struggles, though we can not know all the people themselves; so, with a little trouble, we may learn to picture to ourselves the general life and habits of the different branches of the still greater family of life, so as to be ready, by and by, to make personal acquaintance with any particular creature if he comes in our way.
- From the Introduction to "Life and her Children," in press by D. Appleton & Co.