The winners in life's race

by Arabella B. Buckley

A marvellous change this is, as we can judge by watching our common tadpole, and seeing how during its youth its whole breathing organs are remade on a totally different principle, its heart is remodelled from an organ of two chambers into one of three, the whole course of its blood is altered, some channels being destroyed and others multiplied and enlarged, a sucking mouth is converted into a gaping bony jaw, and legs with all their bones and joints are produced where none were before, while the fish’s tail, its office abandoned, is gradually absorbed and lost.

The only reason why this completely new creation, taking place in one and the same animal, does not fill us with wonder is, that it goes on in the water where generally we do not see it, and because the most wonderful changes are worked out inside the tadpole, and are only understood by physiologists. But in truth the real alteration in bodily structure is much greater than if a seal could be changed into a monkey.

Now this complete development which the tadpole goes through in one summer is, after all, but a rapid repetition, as it were, of that slow and gradual development which must have taken place in past ages, when water-breathing animals first became adapted to air-breathing. Any one, therefore, who will take the spawn of a frog from a pond, and watch it through all its stages, may rehearse for himself that marvellous chapter in the history of the growth and development of higher life.

And he will gain much by this study, for all nature teaches us that this is the mode in which the Great Power works. Not “in the whirlwind,” or by sudden and violent new creations, but by the “still small voice” of gentle and gradual change, ordering so the laws of being that each part shall model and remodel itself as occasion requires. Could we but see the whole, we should surely bend in reverence and awe before a scheme so grand, so immutable, so irresistible in its action, and yet so still, so silent, and so imperceptible, because everywhere and always at work. Even now to those who study nature, broken and partial as their knowledge must be, it is incomprehensible how men can seek and long for marvels of spasmodic power, when there lies before them the greatest proof of a mighty wisdom in an all-embracing and never-wavering scheme, the scope of which is indeed beyond our intelligence, but the partial working of which is daily shown before our very eyes.

But to return to our shifting scene where the dense forests of the Coal Period next come before us. There, while numerous fish, small and great, fill the waters, huge Newts have begun their reign (Labyrinthodonts), wandering in the marshy swamps or swimming in the pools, while smaller forms run about among the trees, or, snake-like in form, wriggle among the ferns and mosses; and one and all of these lead the double-breathing or amphibian life.

In the next scene the coal forests are passing away, though still the strange forms of the trees and the gigantic ferns tell us we have not left them quite behind; and now upon the land are true air-breathers,[192] no longer beginning life in the water, but born alive, as the young ones of the black salamander are now (see [p. 81]). The Reptiles have begun their reign, and they show that, though still cold-blooded animals, they have entered upon a successful line of life, for they increase in size and number till the world is filled with them.

Meanwhile other remarkable forms now appear leading off to two new branches of backboned life. On the one hand, little insect-eating warm-blooded marsupials scamper through the woods, having started we scarcely yet know when or where, except that we learn from their structure that they probably branched off from the amphibians in quite a different line from the reptiles, and certainly gained a footing upon the earth in very early times. On the other hand, birds come upon the scene having teeth in their mouths,[193] long-jointed tails,[194] and many other reptilian characters. We have indeed far more clue to the relationship of the birds than we have of the marsupials, for while we have these reptile-like birds, we have also the bird-like reptiles such as the little Compsognathus, which hopped on two feet, had a long neck, bird-like head and many other bird-like characters, though no wings or feathers.

The birds, however, even though reptile-like in their beginning, must soon have branched out on a completely new line. They for the first time among this group of animals,[195] have the perfect four-chambered heart with its quick circulation and warm blood; while not only do they use their fore limbs for flying (for this some reptiles did before them), but they use them in quite a new fashion, putting forth a clothing of feathers of wondrous beauty and construction, and with true wings taking possession of the air, where from this time their history is one of continued success.

And now we have before us all the great groups of the backboned family—fish, amphibia, reptiles, birds and mammalia; but in what strange proportions! As the scenery of the Chalk Period with its fan-palms and pines comes before us, we find that the gristly fish, except the sharks and a few solitary types, are fast dying out, while the bony fish[196] are but just beginning their career. The large amphibians are all gone long ago; they have run their race, enjoyed their life and finished their course, leaving only the small newts and salamanders, and later on the frogs and toads, to keep up the traditions of the race. The land-birds are still in their earliest stage; they have probably scarcely lost their lizard-like tail, and have not yet perfected their horny beak, but are only feeling their way as conquerors of the air. And as for the milk-givers, though we have met with them in small early forms, yet now for a time we lose sight of them again altogether.

It is the reptiles—the cold-blooded monster reptiles—which seem at this time to be carrying all before them. We find them everywhere—in the water, with paddles for swimming; in the air, with membranes for flying; on the land hopping or running on their hind feet. From small creatures not bigger than two feet high, to huge monsters thirty feet in height, feeding on the tops of trees which our giraffes and elephants could not reach, they fill the land; while flesh-eating reptiles, quite their match in size and strength, prey upon them as lions and tigers do upon the grass-feeders now.[197] This is no fancy picture, for in our museums, and especially in Professor Marsh’s wonderful collection in Yale Museum in America, you may see the skeletons of these large reptiles, and build them up again in imagination as they stood in those ancient days when they looked down upon the primitive birds and tiny marsupials, little dreaming that their own race, then so powerful, would dwindle away, while these were to take possession in their stead.