ECONOMIC VALUE 127 



winter. They are able to adapt themselves to the change 

 in the seasons without burying themselves in the mud as 

 the frogs do. 



Some of the birds do not migrate, but remain all winter 

 in the North. They have become so well adapted to con- 

 ditions that they are able to get their food where birds 

 that migrate would starve. 



Man is the only animal which is able to live anywhere on 

 the face of the earth under the most varied conditions. 

 To realize this fully we have but to think of the different 

 surroundings of the Eskimo, Indian, Bushman, and of 

 ourselves. 



Each animal and plant is directly dependent upon its 

 environment for food and a home. 



125. Economic Value of Amphibians. — The toad is the 

 only member of the amphibian group that is of any great 

 value to man. It destroys many insects. Frogs eat a few 

 but hardly enough to entitle them to high rank as bene- 

 ficial animals. Their chief value is as food and as conven- 

 ient forms for dissection in biology courses. 



SUMMARY 



The Amphibians are an interesting group which illus- 

 trates how water animals may have become land animals. 

 The frog has well-developed sense organs, legs modified 

 for jumping, and feet for swimming. The skin is moist and 

 helps to serve as an organ of respiration. The color mark- 

 ings and the habits of the frog serve to protect him from 

 many of his enemies. 



QUESTIONS 



What animals belong to this class? How can yon tell them from fish ? 

 Where do the amphibians of your region live? Bow many kinds d<> 

 you know ? 



