THE AMPHIBIA 175 



capable of making a noise which seems absurdly out of 

 proportion to their diminutive bodies. Their song is more 

 apt to be made in a moist atmosphere and this probably 

 accounts for the fact that it is commonly regarded as pro- 

 phetic of rain. 



Nearly all the tailless amphibians undergo a metamor- 

 phosis, the early stages of which are passed in the water. 

 In our common frogs and toads the larva, or tadpole, as 

 it emerges from the jelly in which it has passed its em- 

 bryonic development, is furnished with three pairs of 

 external gills and a flattened tail by which it swims 

 through the water much after the fashion of a fish. The 

 young tadpole lives mainly on aquatic plants, although 

 it may eat animal food also when occasion offers. As the 

 tadpole grows, legs bud out; first the hinder pair and later 

 the anterior ones. During the development of the lungs, 

 the gills gradually disappear and the tadpole frequently 

 comes to the surface for air. With the growth of the legs 

 the tail becomes shorter and is finally resorbed into the 

 body. While these changes are going on the young frog 

 or toad, as we may now call it, gradually comes to move 

 about on the land. Four or five years are required for 

 our common species of frogs to become sufficiently mature 

 to produce young, and they may live four or five years 

 longer if they are fortunate enough to be spared from their 

 many enemies. 



