128 ANIMAL BIOLOGY 



In what state of growth are the legs when the tadpole 

 first goes to the surface to breathe ? Which legs appear 

 first ? 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 tad- 

 pole 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 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 color, or tint, is most 

 prominent on a frog ? Does the color " mimic " or imi- 

 tate its surroundings ? What is the color of the under 

 side of the body ? (Fig. 250.) Why is there greater 

 safety in that color ? 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 



