FROGS, TOADS, SALAMANDERS, SNAKES, ETC. 151 



and breathes the air in the water with its gills. At this time 

 the food is mainly vegetable, consisting of minute algal 

 vegetation. 



Gradually, as the tadpole grows, lungs develop. Also about 

 this time limbs develop. Finally the tail disappears, not 

 by dropping off, but by gradual absorption and transfer of 



FIG. 32. Development of a Tadpole. 



its substance to other parts. This loss of the tail applies only 

 to frogs and toads. Salamanders, mud-puppies, etc., retain 

 them. 



After the limbs and lungs have developed, most amphibians 

 leave the water and breathe the air, their gills usually first 

 disappearing. Thus frogs, toads, and salamanders become 

 more or less terrestrial. This does not mean that they shun 

 the water thereafter. In fact, frogs continue to live what we 

 generally call an amphibious life. They like moist places, wet 

 meadows, damp woods, and many species spend a good share 

 of their lives sitting half-submerged in the water of swamps 

 and lakes. Salamanders are found in damp cellars or in damp 



