be very voracious. The terrestrial and arboreal forms feed mainly on insects, worms, etc. The aquatic kinds also catch insects, but subsist more on aquatic animals--#8212;worms, tadpoles, small fishes, and other Frogs. These are seized and slowly swallowed, often, where before the remainder, perhaps still alive, has been got within the mouth.

Extremes of cold or drought in climate must be avoided by Frogs. Moisture of the skin is necessary to their health, and in very dry places or seasons they survive only by going deeply under ground. Thus some tropical species get through the "dry season." The frogs of northern climates endure the winter by clustering about spring-holes and other places where the water is comparatively warm and free of ice; or else by hibernating in the mud. Terrestrial species bury themselves for the winter in the loam, or burrow into the dry dust of rotting logs and stumps. Their vitality is strong, and their power of regeneration from partial congelation is very great.

Though most species live always in or near water, many spend the greater part of their time away from it, and often in bushes or trees. These, however, go to the water to breed; and as this function is likely to demand attention early in the spring, it is then that these animals make themselves most conspicuous by the incessantly uttered croaking or rattling calls of the males, which are almost as varied as the songs of the birds, and more ventriloquistic. These are wholly the cries of the male Frogs, and cease when the mates have been found and have spawned; and to assist in producing them many species have gular air-sacs, which are connected with the vocal organs and furnish the power required for the loud and insistent utterances. The great ear-drums correlated with this vocal power are conspicuous in many species.

The reproductive habits of Frogs are various. All of our common species lay their eggs in water, the eggs being fertilized as they are laid. As the eggs are laid they are inclosed in a gelatinous envelope secreted by the female. This swells and protects the eggs from injury, from being fed upon, from the direct rays of the sun, and in some species it serves to float the eggs at the surface of the water, where oxygen is most abundant; finally, the envelope serves as food for the young frogs. The mouth of the tadpole is small and provided with a horny beak, which takes the place of the teeth which are not yet developed. The tadpole feeds on algæ that cover stones, and on the flesh of dead animals. The long, spirally coiled intestine, which can be seen on the under side of the animal, is an adaptation to its prevailingly herbivorous diet, which requires a prolonged digestion.

The tadpole usually lives in the water for two or three months before it takes to land. In the Bullfrog, however, the transformation (see Toad) does not take place until the second summer.

In many tropical Frogs the reproductive habits are much modified. One species (Phyllobates trinitatis) of Venezuela and Trinidad carries its tadpoles on its back, to which the young attach themselves by means of their suckers. A frog of the Seychelles Islands lives in the tree-ferns far from water, and carries its young about on its back, to which they are attached by their bellies. In the Kameruns lives a Frog that lays its eggs in a foamy mass on the leaves of a tree. When the larvæ are developed the mass becomes slimy and the tadpoles swim about it, and when a heavy rain falls they are washed into pools of water lying at the bases of the trees. The foam is probably produced as it is in culinary operations, by air being entangled in it by a beating that the Frog gives the jelly with its feet. The inclosed air may well serve in respiration. Compare Toad.

Utilities. Among both civilized and savage men Frogs are a culinary dainty. The edible European Frog is so much prized in France that it is bred for the market in large preserves. In the United States both the Bullfrog and spring Frog are sold in the markets. In France and the United States the hind legs alone are eaten; they are known as "saddles" to American marketmen, and are usually served at table fried. In Germany all the muscular parts are served stewed, often with sauce. Frogs have enabled man to contribute much to his knowledge of physiology. The tail of the tadpole, so frequently fed on by dragon-fly larvæ and other aquatic enemies, has great capacity of regeneration. The study of its re-formation has added to our knowledge of the regeneration of animal tissue. The circulation of the blood, so readily seen by the aid of the microscope in the web of the Frog's foot, is a classic and painless classroom demonstration. Observations on the response of Frog-muscle to stimuli led the great Italian physiologist Galvani to the discovery of dynamical or current electricity, known to us as galvanic or voltaic electricity.

THE MALE FROG. (See Blower.)

Nests and Nest Building.

Whenever the spawning period occurs, ample warning will be given, as the male Frogs will begin croaking for their mate, and will be seen near the shore. Early in the spring is the breeding season, and the Frogs will be seen in pairs, working in company, selecting nests, which are in place where there is a vegetation to attach the spawn, near the surface of the water, as the action of the sun has much to do with the hatching of the spawn.

Impregnation takes place immediately after the spawn is deposited, as with the spawn of fish. The spawn of frogs looks like a gelatin mass in the shape of a bunch of grapes, and will be found attached to some vegetation in the pond. This should be immediately taken out with a large, long handle dipper and deposited in the hatching pond, as the spawn will be destroyed by the frogs jumping into the pond and coming in contact with it, for if the spawn is separated or broken up and sinks to the bottom of the pond, where it cannot get the proper action of the sun, many of the eggs will not hatch, but will be destroyed and eaten. The nursery, or hatching pond, should be constructed in this way: Make some skeleton frames that will set on the bottom of the pond, and come within a few inches of the top of the water. Fasten the frames down, either by weights or stakes driven in the ground. Take some fine netting such as used on windows to keep out flies; cotton or flax netting preferred to wire. Fasten this netting to the frame. Be sure that the netting is always covered with water when spawn is on it. On this netting, deposit the eggs or spawn taken from the breeding pond. In this way it will be undisturbed, and the sun can do its part toward the hatching of the eggs. This method will be found successful, and you can watch the progress, and the influence of the sun and water on the hatching of the eggs and note the change from day to day, as the Frogs have nothing more to do with their development. Another reason for separating the eggs or spawn from the breeding ponds is, when the spawn is hatched into tadpoles, the Frogs will eat the tadpoles as fast as they wiggle out of the egg. In fact, Frogs are cannibals, and will eat the young until they get large enough to protect themselves.

This is why ponds should be constructed so that Frogs of different sizes can be separated, and all of about a size, kept in ponds by themselves, and raised together. By this arrangement you save many small Frogs.

Enemies of Spawn, Tadpoles and Small Frogs.

The enemies must be guarded against by proper fencing with wire netting and boards. A board should be sunken into the ground at least three inches, and 2 foot 2 inch mesh wire fastened on it. If a 12-inch board is used, this will make a