RANA AND BUFO.
Belonging to the lower vertebrates is a family of animals called scientifically Ranidæ, but which are, popularly speaking, best known as frogs. They are queer-looking creatures, scarcely met with in Australia and South America, but reaching their highest state in the East Indies. They are capable of enduring great changes of heat and cold, and can live on land as well as in water, provided they have the amount of moisture necessary to preserve the suppleness of their skins. Salt water is fatal to the frog in any stage of its existence.
Rana clamata, the lusty croaker of the summer pond, is our most familiar species. He may be recognized by the colors of his dress, in which green, bronze, gold and silver play important parts, and by the ear-splitting character of his vocal intonations. The glandular ridges down the skin of his back, together with his strange coloration, singularly fit him for his home. Imitations of the stems of plants are seen in the darker ridges, and their leafage in the green color of his coat. The silver of his vest has the glimmer of the water in which he bathes, and the moist earth seems to have left its stain upon his brownish feet and markings, while the yellow of the several badges that adorn his person in being like the stamens and pistils of the surrounding flowers, and of the hue of many buds and blossoms, adds largely to his protective display. Thus is the frog in his natural haunts protected by his garments, and, unless he stirs or is betrayed by his full, bright eyes or the palpitation of his breast, he is not likely to be observed.
Four fingers or toes are found upon the anterior extremities, while those of the posterior are five in number and webbed. The front legs are much shorter, smaller and weaker than the hind ones, which are largely developed, and thus serviceable in swimming and leaping.
Though the frog is possessed of a back-bone, yet he has no ribs. Being ribless, he cannot expand and contract his chest in breathing, but must swallow what air he requires. In swallowing the air he must close the mouth and take the air in only by the nostrils; therefore, oddly enough, if his mouth is forcibly kept open, he will smother. The frog’s breathing, a fact not generally known, is partly through his skin, which gives off carbonic acid gas; and moisture, therefore, is just as essential to his skin as it is to the gills of a fish. Damp, rainy weather is his extreme delight. When the rain falls, out come the frogs. Their skin absorbs moisture, which is stored up in internal reservoirs, and some of this water, when these timid creatures are alarmed by being suddenly seized, is ejected, but I do not think that it is purposely so done, as the water is not, as some people have fancied, of a poisonous nature. Frogs have no poison-sacs, and in truth no weapons of any kind.
Open a frog’s mouth, and you will find but a few tiny teeth in the upper jaw and palate, which are useful for the partial grinding up of horny insects. His tongue you will discover to be a very odd affair, which is fastened at the front end of the mouth, the hinder part being free and hanging down the creature’s throat. This organ is covered with a glue-like secretion. When an insect is to be captured, it is snapped forward from the mouth, and, striking the insect, which it seldom fails to do, causes it to adhere as to bird-lime.
A few thoughts now about the life-history of the frog. From egg to egg is the story. In roundish masses, upon sticks lying in water, or upon the leaves and stems of submerged water-plants, are the eggs deposited. The creature that comes from the egg is no more like a frog than a caterpillar is like a butterfly. It has a large head, small tail, branched gills, and is devoid of limbs, resembling, in this stage, more a fish than a frog. This is its early childhood, or tadpole state. It can only live in water now, and swims and feeds from the very moment it leaves the egg. Change in form almost immediately begins, the branched gills being drawn within the neck and hidden, a pair of fore-legs beginning to bud, and subsequently a pair of hind-legs, which push out much faster than the fore-legs. As the legs grow, the tail is gradually absorbed and disappears. The interior of the body meanwhile changes, the lungs and heart becoming reptilian. When the gills and tail are gone, and the legs are fully formed, the once-swimming tadpole hops out of the water a perfectly-formed frog.
When first the tadpole emerged from the egg, it ate the jelly-like cover. Then soft animal and vegetable matters, with the strengthening of its pair of horny jaws, began to be devoured. Insects later on, and even its own kith and kin, became its food. The fare of the adult frog is almost exclusively insect in character, although necessity sometimes drives him to make a meal out of some of his weaker brethren.
Seated in cool, leafy shadows, not far from his favorite stream or pool, the frog watches with his great, black, gold-ringed eyes for such insects as good fortune shall bring to his retreat. As one hovers near, out flies his limber, sticky, ribbon-like tongue, true to its mark, and the hapless insect, adhering to the viscid projected ribbon, is gently and cleverly deposited in the open throat, the frog maintaining all the while an air of calm, superior self-satisfaction, as if he had not so much satisfied an appetite as fulfilled the mission of ridding nature of a superfluous insect.
A most harmless, timid and interesting animal is the frog, and often most unfortunate. He is the legitimate mark for all the missiles that can be thrown at him by urchins wandering about his native pool. Snakes make him their prey, and he is always in mental fear lest some insidious serpent shall take him unawares, or his musings shall be suddenly cut short by the stately progress of some swan or goose, sailing over the limpid water, or searching the green herbage wherein he sits concealed.
RANA CLAMATA, OR GREEN FROG.
Lusty Croaker of the Summer Pond.
That he is susceptible of being trained, there can be no question. Man is not always viewed by him as an inveterate enemy, nor does he always dive headlong into the pool when his presence is near. He has been known to cultivate man’s acquaintance, and to live on friendly terms with him. Some three years ago a tiny frog was taken from a swamp by a friend and placed in a small stream of spring water that passed close to the house where the writer was summering. A dozen times a day the little frog was dipped up by the hand from the bottom of the stream, and forced to endure down the head and back the tenderest caresses. A few insects were then offered as food in conciliation for the liberty taken, which the little frog was only induced to accept after a great deal of persuasion, when he was carefully put back into his watery bath. In the space of a week, the frog had become so attached to his friend, that he would leap into his outstretched hand and take his food without the least distrust or fear. Even the voice of the master was recognized by the frog, and, when heard in the distance, was the signal for the strangest behavior. Froggie would leap out of the water upon a bare stretch of earth, peer off in the direction whence the sound came, and there await his master’s arrival with restless anxiety. The strongest bond of friendship seemed to unite the two. Not only was the frog able to recognize the voice of his friend, but he knew him in person as well. Repeated efforts were made by the writer to gain the attention and good-will of the frog, but all his advances were received with the utmost indifference.
While the species which I have just described represents the aquatic Ranidæ, the Wood-frog, its near kin, represents a branch of the family which prefers dry situations, except in breeding times, when the eggs must be deposited in water. The Wood-frog is somewhat smaller than the Bull-frog, and is clad in olive-green and brown colors, which are in perfect keeping with the coloration of dead leaves and dry twigs. There is a large black patch on the side of the head around the big ear-drum, which seems still further to distinguish him from his cousin. He is a very shy and suspicious creature, and makes a prodigious jump at the first intimation of danger, his leaps being so enormous that it is very difficult to capture him. When upon the ground, he can hardly be discerned from the dry vegetation around. By hiding in damp moss or in decayed logs, and in little hollows in the ground, he is enabled to maintain the moisture of his skin. He avoids the sunshine, and keeps close to the earth.
Another curious Rana is the Tree-frog. He is smaller than any of his cousins, and may be known by his bright green dress, which is spotted with black, and by a membrane stretched between his toes, which gives him a broad, flat surface, while it helps to sustain him as he leaps, somewhat after the fashion of a flying squirrel, from branch to branch. In tropical regions, where many of the trees are bedecked with gorgeous blossoms, Tree-frogs appear in the gayest of colors, the splendor of their garb being protective in such surroundings.
Dressed in black and light brown, and living in marshes in the Eastern United States, is another species—the Swamp-frog. His voice is a prolonged croak, which, to the practised ear, can be readily distinguished from the bawl of Clamata, or the roar of the Bull-frog.
Cats, geese, hawks, vultures, owls and other animals eat frogs, and the luckless creatures can scarcely appear without finding an enemy. But nature, who is a very wise and considerate mother, provides a means for balancing this great destruction of their forces in endowing them with wonderful reproductive organs. So prolific are frogs, that when the little black tadpoles appear, so thickly are they huddled together that the pond seems literally alive with their swimming forms.
In the same class of animals to which the frogs belong, as well as to the same order, but to a different sub-order, are placed the toads, somewhat remote cousins of the frogs. As the frog is well-known about our ponds, so the toad is a constant denizen of our groves and gardens. The frog, you have been told, is a species of Rana, and now I shall introduce to you the toad as a species of Bufo. In general anatomy they are alike. Their eggs and young are closely similar, and the stages of growth from egg to adult form are nearly identical. When the adult stage is attained the frogs and toads are very tiny creatures, but, small as they are, they are readily distinguishable from each other by the conformation of the snout, and by the larger development of the hind-legs of the frog. Their chief differences will now be enumerated. The toad has no teeth, but the frog, as has been stated before, has teeth in both the upper jaw and the palate. Similarly attached is the tongue, but the free end of the frog’s tongue is forked, and the toad’s entire. The skin of the toad is usually warty, while the frog’s is smooth. A rounder body, shorter hind-legs, less fully webbed feet and more rounded snout still further distinguish the toad from the frog. Their soft moist skin shows them to be Amphibians. The absence of tails places them among the Anuran, or Tailless Amphibians. Thus far they agree well together, but differences loom up upon careful examination, and we are compelled to say of the frog that he belongs to the Ranidæ, and of the toad that he belongs to the Bufonidæ. Of the two animals, the toad is by far the more interesting and useful.
The toad is almost unrestricted in his territorial range. He hops through the tropics and the temperate zones, and well up into the polar regions. Everywhere he is the same inoffensive, gentle, humble, useful and generally silent creature. But like his human brother he has his faults. He has a great fondness for bees. Happy is he when, brigand-like, he can stand by the highway of the bees and capture them as they return to their waxen city. Their wealth of honey he does not demand as a ransom, but swallows the little creatures themselves, alive and whole, and digests them at leisure. Bee-eating seems his only fault. Not only the hive-bee, but other insects as well, share his attention. Millions of noxious beetles and bugs are devoured, and the world is the richer by thousands of bushels of fruit and vegetables. The good he accomplishes largely outweighs the mischief he commits. So ceaselessly and swiftly he swallows his game, that a grasshopper’s legs or a sphinx’s antennæ may often be seen sticking out of his mouth, while the carcass itself is well down in his throat. French gardeners so appreciate his utility that he is brought to market and sold for a pittance to such as may need his services.
COMMON AMERICAN TOAD.
How He Manages a Difficulty.
Toads can be tamed and taught to eat from the hand. They are easily beguiled with sugar and with bread that has been soaked in milk, but, like a captious child, they eat only the middle out of the slice, and leave the crust. We once saw a toad, a noble fellow he was, who, at a certain hour of the closing day, would come from his gloomy retreat to receive at the hands of man his supper of flies, which he had been trained to catch on the throw. So unerringly would his tongue dart out at the opportune moment, that he seldom, if ever, shot wide of his mark. It is amusing to observe him when, in his greed and haste, he has attempted to swallow a huge grasshopper whose legs will not accommodate themselves to his peculiar gape of mouth. How he swallows and twists and contracts the walls of his throat, but the legs seem unmanageable. He does not give up, or endeavor to eject the half-swallowed body, but ponders the matter over and over. A look of delight beams out of his eyes, that shows he has managed the problem. Up goes to the mouth the right fore-leg, and, in less time than it takes to chronicle the event, the obstreperous insect is pushed into the stomach.
Some curious myths are told of the toad. One says he can live for hundreds of years encased in clay or in stone. No more true of Bufo is this than of Rana, his cousin. Another asserts that his skin, when handled, is productive of warts, and that the fluid he emits, which serves but to moisten his body, for without moisture he could certainly not live, and to protect him from enemies, is poisonous in character. His power to produce warts, we cannot admit. But that the fluid he exudes, if not poisonous to touch, is offensive to animals, there can be no doubt. We are led to this conclusion from the following considerations: Dogs, young animals especially, are prone to attack the toad, but they never want to repeat their experience. The toad’s exudation so affects the salivary glands of the dog as to cause him to froth and foam like an animal with rabies. A case is recalled where a dog, that had taken a toad in his mouth, became almost frantic. This dog never afterwards was well. His whole system apparently had become diseased, and, in less than a year, he had wasted to a complete skeleton, when death relieved him of his sufferings. Another allegation, that the toad has a jewel in his head, has been believed from very ancient times. The story doubtlessly originated from the beauty of the toad’s eyes, the irides being a rich flame-color, which, in the dusk of the even, shine like burnished gems.
When hatched the young of the toad are of a jet black color, and are very active. Their changes are made very early and in the same manner as those of the frog. They are quite small when arrived at the perfect toad state. Their legs produced and their tails absorbed, they quit the water and set out on long journeys. Unlike the frog, which is a home-stayer, the toad is a born vagrant. They travel chiefly by night, hiding under stones and herbage during the day. If clouds cover the sky, they take heart and joyously hop forth upon their pilgrimage. During a long drouth they mysteriously disappear, but if a rain comes on they suddenly come out by hundreds, and this has given rise to the tale of a “shower of toads.”
Worms, as well as flies, etc., constitute a toad’s bill of fare. After a rain toads and worms, it would seem, are mutually inspired to take their walks abroad, and many an unfortunate worm makes its way into the toad’s maw. Dead insects are at a discount with him, and he views with suspicion anything that shows not the active wriggling principle of life. When winter comes on the toad, like the frog, goes into winter-quarters. Since the young toad reaches its adult size in the autumn, it is forced to pass the first period of its grown-up life in a sleep, or coma, in some hole or burrow which it has found or fashioned in the earth. Sometimes toads creep into rock-crevices, or into hollows in logs and trees, and being found in these places in the early spring are hastily supposed to have been prisoners for many years.
In the process of growth the skin of the toad, as well as that of the frog, becomes too small, and hence is cast off. As the shedding-time approaches, the white, green and brown colors become dull, and a peculiar dryness appears. A new skin is now forming under the outgrown one, and presently the latter splits half down the middle of the back and along the under part of the body. By a series of violent twitchings of the toad the old skin is made to wrinkle and fold along the sides. A hind-leg is now tucked under a fore-arm, and by a good pull the animal is soon out of that leg of his trousers. The other leg is removed in similar fashion. Putting one hand in his mouth and giving a jerk, off comes the covering of that hand and arm, like a discarded glove. He has now but to take off the other, and he is free. Relieved of his dress he neither sells nor gives it away, but rolls it up into a neat solid ball and swallows it. The frog strips off and disposes of his outgrown skin in a similar way.
Strange to say, toads and frogs can change to some extent the color of their skin to suit their homes. Kept in the dark with dark surroundings, toads become darker in color, while those that are kept in light with white accessories become lighter. The color of the toad changes more slowly than that of the frog. It is not the arrangement of the color that alters, but merely a change from light to dark.
What has been said applies to our Common American Toad, the Bufo Americana of the books. Let us now look at some curious specimens of the Bufonidæ. The Pipa, or Surinam Toad, does not lay her eggs in water, but places them on her back. A fold of skin rises up and encloses each egg in a separate cell, until the young have not only been hatched, but have also passed through all their metamorphoses, and come out fully formed. Another toad, abundant in Europe and Asia, is largely colored with bright crimson, and the father-toad carries the little ones in separate cells fastened to his hind-legs like chains. The young change to their perfect shape in these cells, and with the withering away of the cells the young toads hop out, able to take care of themselves.
Somewhere I have said that toads are generally silent. A little toad about three inches long, called a Natter-jack, is common in England, and is a noted singer. His “gluck-gluck, gluck-k-k,” can be heard any night. The Green Toad, well known on the Continent, is not so noisy as the Natter-jack, but has a low, moaning cry.
All the Tree-toads, or Hylidæ, have clear, shrill voices, and are fond of singing serenades. In the spring the Common Toad takes to the water and there sings very loudly. The loud continuous trill that we hear in swamps in spring-time is made by toads, and not by frogs, as is generally believed. Another toad with a voice is the Spade-foot. This Toad is rare, though widely distributed. It is remarkable for its feet, formed for digging, its subterranean habits, and its queer way of appearing and disappearing very suddenly. After a rainy season the Spade-foot will emerge from its hiding-place, attract attention by its loud cries, swarm by hundreds about the ponds, lay innumerable eggs, and vanish. But while thousands of eggs are laid, scarcely any hatch, for most of them perish from being laid so near to the water’s edge as to become dried up on the subsidence of the water.
Thus we find that toads have three different methods of life. Some live on trees, but seldom appear upon the ground. Others are underground dwellers, and hardly ever come to the surface. But the Common Toad, and his numerous kin, are dwellers in the ground, hiding among grass and other herbage when asleep, or when the sun is too intense for their comfort. But all toads, excepting the two varieties mentioned above, which carry their young on their bodies, repair to the water to drop their eggs, and the young live in the water until they have attained the adult state.