194 Handbook of Nature-Study 



The frog is likely to be much more brightly colored than the toad, and 

 usually has much of green and yellow in its dress. But the frog lives 

 among green things, while it is to the toad's advantage to be the color of 

 the soil. Frogs also have the chameleon power of changing color, to 

 harmonize with their environment. I have seen a very green leopard 

 frog change to a slate-gray when placed upon slate-colored rock. The 

 change took place in the green portions. The common green frog will 

 likewise change to slate-color, in a similar situation. A leopard frog 

 changed quickly from dark green to pale olive, when it was placed in the 

 water after having been on the soil. 



The eyes of frogs are very prominent, and are beautiful when observed 

 closely. The green frog has a dark bronze iris with a gleaming gold edge 

 around the pupil, and around the outer margin. The eye of the leopard 

 frog is darker; the iris seems to be black, with specks of ruddy gold 

 scattered through it, and there is an outer band of red-gold around the 

 margin. When the frog winks, the nictitating membrane rises from 

 below and covers the whole eye; and when the frog makes a special effort 

 of any sort, it has a comical way of drawing its eyes back into its head. 

 When trying to hide at the bottom of the aquarium, the leopard species 

 lets the eye-lids fall over the eyes, so that they do not shine up and attract 

 pursuers. 



The ear is in a similar position to that of the toad, and in the bullfrog, 

 is larger than the eye. In the green frog, it is a dull grayish disc, almost 

 as large as the eye. In the leopard frog, it is not so large as the eye, and 

 has a giltish spot at the center. 



The nostrils are small and are closed when below the water, as may be 

 easily seen by a lens. The mouth opens widely, the comers extending 

 back under the eye. The jaws are homy and are armed with teeth, 

 which are for the purpose of biting off food rather than for chewing it. 

 When above water, the throat keeps up a rythmic motion which is the 

 process of breathing; but when below water this motion ceases. The 

 food of frogs is largely composed of insects, that frequent damp places 

 or that live in the water. 



The sound-sacs of the frogs, instead of being beneath the throat, as is 

 the case with toads and tree-frogs, are at the side of the throat; and when 

 inflated, may extend from just back of the eyes, out above the front legs. 

 The song is characteristic, and pleasant to listen to, if not too close by. 

 Perhaps exception should be made to the lay of the bullfrog, which like 

 the song of some noted opera singers, is more wonderful than musical; 

 the boom of the bullfrog makes the earth fairly quake. If we seize the 

 frog by the hind leg, it will usually croak and thus demonstrate for us, 

 the position of its sound-sacs. 



In addition to the snakes, the frogs have inveterate enemies in the 

 herons which frequent shallow water, and eat them in great numbers. 

 The frogs hibernate in mud and about ponds, burrowing deep enough to 

 escape freezing. In the spring, they come up and sing their spring songs 

 and the mother frogs lay their eggs in masses of jelly on the bottom of the 

 pond, usually where the water is deeper than in the situations where the 

 toads' eggs are laid. The eggs of the two can always be distinguished, 

 since the toads' are laid in strings of jelly, while the frogs' are laid in masses. 



It is amusing to watch with a lens, the frog tadpoles seeking tor their 

 microscopic food along the glass of the aquarium. There are horny 



