FROGS, TOADS, SALAMANDERS, SNAKES, ETC. 153 



ment of these by the internal gills and gill slits, the develop- 

 ment of the legs and the gradual loss of the tail. 



If you do not have good luck with the raising of the tad- 

 poles in the aquarium, have the boys catch some that have 

 been living in the pools and swamps and have developed 

 naturally. Make observations upon these. If there is a 

 small natural pool or tank near the school, place eggs there 

 and good results may be had. 



Frogs are interesting and harmless creatures. Their cheer- 

 ful piping or croaking in the early spring is a pleasant sign 

 of the season, though a large colony of frogs near dwellings may 

 become a considerable nuisance on account of their loud 

 concerts. Different species of frogs have different notes or 

 songs. Some of the smaller ones have shrill cricket-like 

 chirps, while the great bullfrog has a deep base " jug-o-rum" 

 call. At times at night it seems as if all the frogs in a pond 

 were "singing" in concert, all keeping time together beauti- 

 fully. 



Frogs in the tadpole stage are chiefly vegetarian in their 

 diet, but after leaving the water they are almost exclusively 

 carnivorous or insectivorous. They then eat insects of all 

 sorts, worms, spiders, etc. The larger forms will even eat 

 lizards, snakes, and small mammals. 



Frogs and toads have peculiar tongues. They are fastened 

 in front and folded back in the mouth, but may be shot out 

 quickly at an insect or worm, which adheres to the sticky 

 surface and is thus drawn in. Feed a toad some angleworms, 

 mealworms, or insects, and the action of the tongue is well seen. 



Watch a frog breathing. He seems to be swallowing all 

 the time. He is swallowing air which he forces down into his 

 lungs. How do we breathe? When we inhale we increase 



