LESSON XXXI.
A NOISY FAMILY.
“When the hounds of spring are on winter’s traces,The mother of months in meadow or plainFills the shadows and windy placesWith lisp of leaves and ripple of rain.”
“When the hounds of spring are on winter’s traces,The mother of months in meadow or plainFills the shadows and windy placesWith lisp of leaves and ripple of rain.”
“When the hounds of spring are on winter’s traces,The mother of months in meadow or plainFills the shadows and windy placesWith lisp of leaves and ripple of rain.”
“When the hounds of spring are on winter’s traces,
The mother of months in meadow or plain
Fills the shadows and windy places
With lisp of leaves and ripple of rain.”
—A. C. Swinburne.
BROTHER HOP O’ MY THUMB.
BROTHER HOP O’ MY THUMB.
Passing one day beside one of those shallow basins that are dug out of the clay soil of the west, to collect the rainfall and to serve as watering-places for stock, I saw a strange sight. Above the brown and turbid water projected a row of green and yellow roundish knobs. These were placed at intervals eight or ten inches apart, nearly around the edge ofthe basin. Looking closer, I saw that at the base of each knob were two bright, prominent eyes. I laughed, as who would not, considering this living wreath encircling the pond. I had never before seen frogs drawn up in such orderly array.
For frogs these were, silent and alert. Whether fear or the heat of the day had driven them to this position I could not tell. Presently one of the bronze-green knobs elevated itself a little, became evident head and shoulders, rose above the surface of the water with a hop, and paused on the muddy edge of the basin for further observations. Watching carefully I saw that all the knobs moved now and again with a quick, bobbing motion. Connecting this motion with the sudden and final disappearance of numerous insects flying low over the water, I discovered that the neatly ambushed frogs were taking their supper. Presently I tossed a stone lightly into the pond, and at once, with a plash all the noses vanished. A little later, as twilight fell, a loud clangor of dissonant voices told that my frogs were engaged in their evening concert. A family of vocalists are these frogs.
The other day I passed this same pond. A winter of sunny weeks, with neither rain nor snow, had caused the water to dry away until only a few inches lay over the mud in the centre of the hollow.
“Where are all our frogs?” asked Hermie. “Frogs hibernate,” I said. “As winter closes in they bury themselves in masses in the mud under the water. Some degree of moisture is needful to them at all times, and the mud affords all the dampness and warmth necessary. If the pond dries away, and the mud hardens about them, so that they cannotget out, they may live in their imprisonment for a number of months.”
“I have heard,” said Hermie, “that frogs have lived shut up in lumps of coal, in rocks, and in trees, for a great many years. Do you believe that?”
“I should want more reliable witnesses and more accurate information than have ever yet appeared in behalf of these tales. Experiments have shown that frogs and toads soon die if entirely shut away from air and food, though with a very little air and food they can live a long time shut up in wood or clay. An old man told me he had seen a frog taken out of a rock, where it had been buried five hundred years, and when it came out ithowled. Now I know that a frog cannot howl,[63]and I concluded that one part of this marvellous tale was as untrue as the other.”
The frogs, whose scientific name is Ranidæ, belong to the lower vertebrates, and are the largest family of their order. They are scarcely known in Australia and South America, and reach their highest state in the East Indies.
Among the best known of the Ranidæ in England and North America is the bull-frog, noted for his large size, his noisy voice, his green coat laced with gold, and his silvery vest. The most curious forms of frogs are found in South America. The Oceanic Islands usually have very few examples of the order. Frogs can endure great changes of heat and cold, and can live on land as well as in water, provided they have the amount of moisture needed to preserve the suppleness of the skin; but salt water is fatal to the frog in any stage of its existence.
For the study of the Ranidæ let us return to the representative best known to us, the lusty croaker of the summer pond. The frog dressed in green, silver, bronze, and gold is an expert swimmer, a mighty leaper, an ear-splitting vocalist, aquatic in his tastes, never wandering far from his native pond except when sent to market, and thence served up at the table as a dainty. But on the table we should not know him for our frog; only his hind quarters appear, and these skinned and fried are much like the legs of a spring chicken.
A most harmless, timid, and interesting beastie is the frog, and often most unfortunate, being considered a legitimate mark for all the stones that can be thrown at him by urchins wandering around his native pool. Moreover, he is filled with mortal terror when with stately progress a swan or a goose sails over the water or searches in the herbage where he hides.
What can we do to give this victim of geese and small boys a certain human interest, and win for him from the boys respect and friendship, rather than pelting? Let us look at him. We have described the colors of his skin, which is smooth, having no scales or plates. The yellow color is laid upon the bronze-green ground in stripes and spots, the stripes extending from the nose to the end of the back with a shorter stripe on each side. The front feet or hands are divided into four fingers, and the front legs are much shorter, smaller, and weaker than the hind ones, which are largely developed, and are used in swimming and leaping. The feet of the hind legs are webbed and have five fingers or toes.
The frog has a backbone, but no ribs. As he is ribless he cannot expand and contract his chest in breathing, so that he must swallow what air he wants. In swallowing air he must close his mouth and take the air in only by the nostrils; therefore, oddly enough, if his mouth is forcibly kept open he may be smothered.[64]The frog’s breathing is partly through its skin, which gives off carbonic acid gas; and moisture is as needful to a frog’s skin as to the gills of a fish.[65]The frog likes damp, rainy weather, and is as fond as a child of playing in a puddle. As soon as rain falls out come the frogs. The frog’s skin absorbs moisture, which it stores up in an internal reservoir. When a frog is alarmed by being suddenly seized, it ejects some of this water. People have fancied that such water was poisonous, but it is not. Frogs have no poison sacs, and no weapons. Toads also give out a fluid from the skin.
Open our frog’s mouth. There are a few tiny teeth on the upper jaw and palate; these are for partially grinding up horny insects. See this odd tongue; it is fastened at the front end to the mouth, and the hinder part is free and hangs down the creature’s throat. This tongue is covered with a glue-like secretion, and when an insect is to be captured the tongue is snapped forward from the mouth, and the insect adheres as to bird-lime. Some frogs have cheek-pouches, and some drum-like throat-plates, wherewith to make their loud croak.
What is the life history of our frog? From seed to seedis plant-life story; from egg to egg is frog story. The eggs of the frog are deposited in roundish masses attached to sticks lying in water, or to the stems and leaves of submerged water-plants. The creature which comes from this egg is no more like a frog, than a caterpillar is like a butterfly. It has a big head and no limbs, and what of it is not head seems to be tail. In fact, in this stage the creature is more like a fish than a frog, and has branched gills. The gills are nearly covered by a fold of skin. Have you seen it? It is a tadpole. This tadpole can live only in water, and swims and feeds from the first instant of its free life. Change in its shape begins almost immediately: the branched gills are drawn within the neck and hidden; a pair of fore-legs begin to bud, and then a pair of hind-legs bud and push out faster than the fore-legs. As the legs grow the tail is gradually absorbed and disappears. Meanwhile the interior of the body changes; the lungs and heart become like those of a reptile. When first the tadpole emerged from the egg it ate the jelly-like egg cover: then, by means of a pair of little horny jaws, it ate soft animal or vegetable matter. When its gills and tail are gone, and its legs are fully formed, it hops out of the water a perfectly formed frog.
Tadpoles feed on insects and also on each other. They are admirable preparers of small skeletons. Try the tadpole at this trade; drop into his pond a dead mouse, or bird, or frog, or squirrel. Soon you will find a clean, white skeleton, nice enough to put in any museum.
The food of the adult frog is chiefly insects. Less hungry than when in the tadpole state,—for the tadpole like thechild must not only eat to live but to grow—the frog is not often tempted to vary his diet.
The frog, seated in cool leaf shadows, watches with his great, black, gold-ringed eyes for such insects as good fortune shall send past his retreat. As one hovers near, out flies his limber, sticky, notched, ribbon-like tongue, true to its mark. The insect adheres to the viscous surface of the projected ribbon, and is gently deposited in the open throat. During this process the frog maintains a calm, superior, self-satisfied expression, as if in this still hunt he not so much satisfied an appetite, as fulfilled a mission of ridding nature of superfluous insects. He seems to have no malice toward the insects; he is merely giving them an honorable burial, and saving them from the further perplexities of life.
The common frog attains a length of three or four inches.[66]He has glandular ridges down the skin of his back, and these, with his colors, singularly fit him for his home: the darker ridges imitating plant-stems; the green coat, leafage; the silver vest, the glimmer of water; the brownish feet and markings, the moist earth; while the yellow markings add to the protective display, in being like the stamens and pistils of surrounding flowers, and of the hue of many buds and blossoms. Thus the frog in his native haunts is protected by his garments, and is little likely to be seen unless he moves, or is betrayed by his full, bright eyes or the palpitations of his breast.
While the common frog represents the aquatic Ranidæ, his cousin, the wood-frog, represents a branch of the widely distributed family which prefers dry dwellings, except in the breeding season, when the eggs must be deposited in water. The wood-frog is smaller than the bull-frog, and is dressed in olive-green and shades of brown, like the colors of dead leaves and dry twigs. There is a large black patch on the side of the head around the big ear-drum. The wood-frog takes such enormous leaps that it is very difficult to catch. It is shy, and makes a prodigious jump at the first hint of danger. When it drops to the ground it is scarcely discernible from the dry vegetation about it. The wood-frog maintains the moisture of its skin by hiding in damp moss or in decayed logs, and in little hollows in the ground. It avoids the sunshine, and keeps close to the earth.
The tree-frog is another curious frog. Smaller than its cousins, it is dressed in bright green, spotted with black, and has a membrane stretched between its toes, which gives its feet a broad, flat surface, and helps to sustain it as it leaps from branch to branch, somewhat in the fashion of a flying squirrel. In tropical lands, where many trees are decked with gorgeous blossoms, tree-frogs appear very gaily colored, the splendor of the coat being protective in such surroundings.
The swamp-frog is dressed in black and light brown, and lives in marshes in the Eastern United States. Its voice is a prolonged croak. The clamata, or “bawling-frog,” lives about cold, damp springs, and is very noisy. The resounding roar of the bull-frog is a well-known sound. No wonderthat Horace, the Roman poet, wrote that “the noisy frogs from the marshes drive away sleep.”
Cats, geese, owls, vultures, hawks, otters, and other creatures eat frogs, and the luckless creatures can hardly appear without finding an enemy. To balance this destruction of their forces they produce great numbers of eggs. When tadpoles first reach the frog state they are black. I have seen hundreds of them together, so that the pond mud seemed alive and crawling.
FOOTNOTES:[63]Frogs and toads sometimes squeal or cry with pain or terror.[64]As these animals respire also through the skin they may live sometime without breathing through the nostrils.[65]See Nature Reader, No. 3, Lesson 40.[66]Our large bull-frog is eight or twelve inches long. Frogs even one or two feet long (Holder’s Zoölogy) have been found, but such a size is very unusual.
[63]Frogs and toads sometimes squeal or cry with pain or terror.
[63]Frogs and toads sometimes squeal or cry with pain or terror.
[64]As these animals respire also through the skin they may live sometime without breathing through the nostrils.
[64]As these animals respire also through the skin they may live sometime without breathing through the nostrils.
[65]See Nature Reader, No. 3, Lesson 40.
[65]See Nature Reader, No. 3, Lesson 40.
[66]Our large bull-frog is eight or twelve inches long. Frogs even one or two feet long (Holder’s Zoölogy) have been found, but such a size is very unusual.
[66]Our large bull-frog is eight or twelve inches long. Frogs even one or two feet long (Holder’s Zoölogy) have been found, but such a size is very unusual.