CHAPTER XI 



BATRACHIA 



The theory ot evolution teaches that animal life began in a very 

 simple form in the sea, and that afterward the higher sea animals 

 lost their gills and developed lungs and legs and came out to live 

 upon the land ; truly a marvellous procedure, and incredible to 

 many, although the process is repeated every spring in count- 

 less instances in pond and brook. 



In popular language, every cold-blooded vertebrate breathing 

 with lungs is called a reptile. The name reptile is properly 

 applied only to lizards, snakes, turtles, and alligators. The com- 

 mon mistake of speaking of frogs and salamanders as reptiles 

 arises from considering them only in their adult condition. Rep- 

 tiles hatch from the egg as tiny reptiles resembling the adult 

 forms ; frogs and salamanders, as every one knows, leave the egg 

 in the form of tadpoles (Fig. 248). The fact that frogs and 

 salamanders begin active life as fishes, breathing by gills, serves to 

 distinguish them from other cold-blooded animals, and causes 

 naturalists to place them in a separate class, called batrachia 

 (twice breather) or amphibia (double life). 



Tadpoles 



Suggestions. — Tadpoles may be studied by placing a number 

 of frog's eggs in a jar of water, care being taken not to place 

 a large number of eggs in a small amount of water. When they 

 hatch, water plants {e.g. green algae) should be added for food. 

 The behaviour of frogs may be best studied in a tub of water. A 

 toad in captivity should be given a cool, moist place, and fed well. 

 A piece of meat placed near a toad may attract flies, and the toad 

 may be observed while catching them, but the motion is so swift 

 as to be almost imperceptible. Live flies may be put into a glass 

 jar with a toad. Toads do not move about until twilight, except 



126 



