Fig. 5.—Development of the Tadpole.
1. Egg of the Frog. 2. The Egg fecundated, and surrounded by its visicule. 3. First state of the Tadpole. 4. Appearance of the breathing gills. 5. Their development. 6. Formation of the hind feet. 7. Formation of the fore feet, and decay of the gills. 8. Development of the lungs, and reduction of the tail. 9. The perfect Frog.
All who have observed the small ponds and ditches in the country at this season, will have seen these light and elegant crafts swimming on the surface of the water. After a few days, more or less according to the temperature, the little black spot which is the embryo of the egg, and which has developed itself in the interior of the glairy mass which envelops it, disengages itself and shoots forth into the water: this is the tadpole of the Frog.
The body of the tadpole is oval in shape, and terminates in a long flat tail, which forms a true fin; on each side of the neck are two large gills, in shape like a plume of feathers; the tadpole has no legs. These gills soon begin to wither, without aquatic respiration ceasing, however; for, besides these, the tadpole possesses interior gills like fishes. Soon after, the legs begin to show themselves, the hind legs appearing first; they acquire a considerable length before the fore feet begin to show themselves. These develop themselves under the skin, which they presently pierce through. When the legs have appeared, the tail begins to fade, and, little by little, withers away, until in the perfect animal it entirely disappears. About the same time the lungs become developed, and assume their functions. In [Fig. 5] may be traced the successive phases of its transformation from the egg to the tadpole, till we finally reach the perfect Batrachian. Through these admirable modifications we see the Fish, little by little, become a Batrachian. In order to follow this strange metamorphosis, it suffices to gather some Frog's eggs, and to place them with some aquatic herbs in an aquarium, or in a globe with Gold and Silver Fish; it there constitutes a most interesting spectacle, and we advise our readers to give themselves this instructive and easy lesson in natural history.
At present, there exist two species of Frog in Europe: the Green or Edible Frog, and the Common Frog. The Green Frog is that which we have described, and of which we have given a representation in [Fig. 4]. They are found in running streams and stagnant waters. It is this species to which La Fontaine alludes in one of his fables. Common Frogs are smaller than the preceding: they inhabit damp places in fields and vineyards, and only return to the water to breed or to winter.
The flesh of the Edible Frog is very tender, white, and delicate. As an article of food, it is lightly esteemed by some, but undeservedly so. Prepared in the same manner, Green Frogs closely resemble very young fowls in taste. In almost all parts of France Frogs are disdained as articles of food; it is only in the south that a taste for them is openly avowed, and there Frogs are sought for and brought to market. Therefore, I never could comprehend how the notion popular in England, when it is wished to express contempt for Frenchmen, should be to call them Frog-eaters. It is a reproach which might be addressed to Provençals and Languedocians like the author of this work, but not at all to the majority of Frenchmen.
Fig. 6.—Green Tree Frog (Hyla).
The Green Tree Frog is easily distinguished by having little plates under its toes. These organs are a species of sucker, by means of which the animal is enabled, like the house-fly, to cling strongly to any surface, however smooth and polished it may be. The smoothest branch, even the lower surface of a leaf, forms a sufficient hold and support to these delicate organs.