FIG. 248.—METAMORPHOSES OF THE FROG, numbered in order. ] Do =eggs hatch= and tadpoles grow more rapidly in a jar of water kept in a warm place or in a cold place? In pond water or in drinking water? Can the tadpoles be seen to move in the eggs before hatching? When do the external gills show? (Fig. 248.) [Illustration: FIG. 249.—TADPOLE, from below, showing intestine and internal gills. (Enlarged.) ] What =parts= may be described in a tadpole? What is the shape of the tail? _Compare the tadpole with the fish_ as to (1) general shape, (2) covering, (3) fins, (4) tail, (5) gills. Do the external =gills= disappear before or after any rudiments of limbs appear? (6, 7, Fig. 248.) Can you locate the gills after they become internal? (Fig. 249.) In what state of growth are the _legs_ when the tadpole first goes to the surface to breathe? Which legs appear first? Of what advantage is this? What becomes of the tail? Is the tail entirely gone before the frog first leaves the water? Are tadpoles habitually in motion or at rest? Is the =intestine= visible through the skin? (Fig. 249.) Is it straight or coiled? Remembering why some fish have larger intestines than others, and that a cow has a long intestine and a cat a short one, state why a tadpole has a relatively longer intestine than a frog. =Compare= the mouth, jaws, eyes, skin, body, and habits of _tadpole and frog_. FROGS Prove that frogs and toads are _beneficial to man_. Did you ever know of a frog or a toad destroying anything useful, or harming any one, or causing warts? How many pupils in class ever had warts? Had they handled frogs before the warts came? Frogs are interesting, gentle, timid animals. Why are they repulsive to some people? =Environment=.—_Where are frogs found_ in greatest numbers? What occurs when danger threatens them? What _enemies_ do they have? What colour, or tint, is most prominent on a frog? Does the colour “mimic” or _imitate_ its surroundings? What is the colour of the under side of the body? (Fig. 250.) Why is there greater safety in that colour? What enemies would see water frogs from below? Do tree frogs mimic the bark? The leaves? Can a _frog stay under water_ for an indefinite time? Why, or why not? What part of a frog is above the surface when it floats or swims in a tub of water? Why? Do frogs croak in the water or on the bank? Why do they croak after a rain? Do toads croak? Are the _eggs_ laid in still or in flowing water? In a clear place or among sticks and stems? Singly, or in strings or in masses? (Fig. 248.) Describe an egg. Why do frogs dig into the mud in autumn in cold climates? Why do they not dig in mud at the bottom of a pond? [Illustration: FIG. 250.—PAINTED FROG (_Chorophilus ornatus_), of Mexico. ]