164 



LIFE PROCESSES OF MAN 



but the body wastes faster than it can be repaired and 

 death is the final result. Old age occurs at different 

 ages in different individuals ; and the same is true of 

 animals and plants. 



STUDENT REPORT 



Fill out the following table and describe the digestive system of the 

 animals studied thus far in Part I. This will help you to understand 

 better the parts of the digestive system of man and the work that each 

 part does. 



Paramo3cium 



Hydra 



Earthworm 



Frog 



Man 

 Etc. 



Which 



Ones 



Require 



Food ? 



144. Digestive Organs. — The digestive organs of man 

 consist of the same parts which have already been described 

 for the frog. Each region of the digestive organs is more 

 perfectly developed and the biological principle, the di- 

 vision of labor, readies its highest -development in man. 

 The parts of the alimentary canal in man are : the 

 mouth, containing the teeth, tongue, and glands ; the 

 throat or pharynx; the esophagus, the stomach, the small 

 and the large intestine. The last part of the large in- 

 testine is called the rectum. These several parts form a 

 continuous tube, and each does a particular work in di- 

 gestion (Figures 178 and 179). 



The mouth is lined with a soft membrane, kept moist by 

 the saliva secreted by three pairs of glands, and poured 



