You will notice that the tiny spheres are not uniformly coloured but that half is whitish. If the eggs have been recently laid the surface will be smooth and unmarked, but have patience and watch them for as long a time as you can spare. Whenever I can get a batch of such eggs, I never grudge a whole day spent in observing them, for it is seldom that the mysterious processes of life are so readily watched and followed.
Keep your eye fixed on the little black and white ball of jelly and before long, gradually and yet with never a halt, a tiny furrow makes its way across the surface, dividing the egg into equal halves. When it completely encircles the sphere you may know that you have seen one of the greatest wonders of the world. The egg which consisted of but one cell is now divided into two exactly equal parts, of the deepest significance. Of the latter truth we may judge from the fact that if one of those cells should be injured, only one-half a polliwog would result,—either a head or a tail half.
Before long the unseen hand of life ploughs another furrow across the egg, and we have now four cells. These divide into eight, sixteen, and so on far beyond human powers of numeration, until the beginnings of all the organs of the tadpole are formed. While we cannot, of course, follow this development, we can look at our egg every day and at last see the little wiggle heads or polliwogs (from pol and wiggle) emerge.
In a few days they develop a fin around the tail, and from now on it is an easy matter to watch the daily growth. There is no greater miracle in the world than to see one of these aquatic, water-breathing, limbless creatures transform before your eyes into a terrestrial, four-legged frog or toad, breathing air like ourselves. The humble polliwog in its development is significant of far more marvellous facts than the caterpillar changing into the butterfly, embodying as it does the deepest poetry and romance of evolution.
| Blue dusk, that brings the dewy hours, Brings thee, of graceless form in sooth. Edgar Fawcett. |
INSECT PIRATES AND SUBMARINES
Far out on the ocean, when the vessel is laboriously making her way through the troughs and over the crests of the great waves, little birds, black save for a patch of white on the lower back, are a common sight, flying with quick irregular wing-beats, close to the surface of the troubled waters. When they spy some edible bit floating beneath them, down they drop until their tiny webbed feet just rest upon the water. Then, snatching up the titbit, half-flying, they patter along the surface of the water, just missing being engulfed by each oncoming wave. Thus they have come to be named petrels—little Peters—because they seem to walk upon the water. Without aid from the wings, however, they would soon be immersed, so the walking is only an illusion.
But in our smallest ponds and brooks we may see this miracle taking place almost daily, the feat being accomplished by a very interesting little assemblage of insects, commonly called water skaters or striders. Let us place our eyes as near as possible to the surface of the water and watch the little creatures darting here and there.