MUCH has been written about frogs. Many interesting stories have been told about them. Almost everyone who has ever lived in the country has been lulled to sleep by the music of a frog chorus. A familiar sight on a summer day is that of a small green frog sunning himself on a log or a lily pad near the lake's edge. If he hears a noise or sees a shadow, he will leap into the water and swim away with swift, sure strokes of his long legs, often swimming a few strokes away from the log, then turning back again. A frog seldom comes to the surface where you expect him. He can breathe through his skin under water and can stay under for a long time. When he comes to the surface, he takes a fresh supply of air into his lungs. Although he cannot breathe through his nostrils under water, a frog can croak without coming to the surface. The sound is produced when air from his lungs passes through the vocal cords in his throat. He does not need to open his mouth to croak, as he can force air from his lungs into his mouth cavity, then back again.

A frog's body can more easily be compared with ours than with that of an insect or a crayfish. You will recall that insects and crayfish have exoskeletons. The frog has bones which are covered by muscles and skin. He has lungs for breathing and blood to carry the oxygen all through his body. His bony skeleton is similar to ours.

Almost everyone has found masses of frogs' eggs in ponds or lakes in the spring. Each dark spot in the mass is an egg. At first the tadpoles which develop from these eggs look more like fish than frogs. Gradually legs appear and the tadpole begins to look more like its parents. The long tail is absorbed and completely disappears. Very young tadpoles breathe by means of gills. Lungs later develop, and the gills disappear. Thus a tadpole which cannot live out of the water becomes a frog which may drown in the water if he is kept under too long.