CHAPTER XVII 



RESPIRATION, BLOOD, AND EXCRETION 



156. Respiration is the life process in which oxygen is 

 used in, and carbon dioxide eliminated from, the cells of 

 the bodies of plants and animals. All animals carry on 

 respiration, and in all the process is alike, although the 

 various animals use different structures to secure the inter- 

 change of oxygen and carbon dioxide. The hydra and 

 earthworm use the entire surface of the body in this 

 process ; the fish has special organs, the gills, while the 

 frog and man have lungs. 



Student Report on Respiration 



In order to help comparison the teacher may explain about the plant. 



Organs of Respiration in Man. — Air enters the nose 

 and passes into the windpipe or trachea (tra/ke-a). The 



192 



