CHAPTER VII. 



Digestion. Waste of the organism repaired by alimentation. Hunger. 

 Thirst. Organs of digestion ; abdominal cavity, peritoneum. Diges- 

 tive apparatus. Mouth, lips, cheeks, teeth, palate, soft palate, tongue. 

 Pharynx. (Esophagus. Stomach. Intestinal canal; small intestine, 

 large intestine, intestinal convolutions, mesentery, omen turn. Mucous 

 membrane. Liver. Pancreas. Spleen . Kidneys. Mechanism of 

 digestion. Digestion of the stomach, gastric juice, peristaltic movement, 

 chyme. Intestinal digestion, bile, pancreatic juice, chyle. Absorption; 

 endosmosis, exosmosis, functions of the veins and lymphatic vessels in 

 absorption, rapidity of absorption. 



Digestion. The human body loses every day through vari- 

 ous channels, by exhalation or excretion, about 310 grains 

 of nitrogen, an essential principle of animal matter, and 

 6^2 Ibs. of water, and burns io*/2 ounces of carbon in 

 contact with the oxygen of the atmosphere. A very short 

 time, therefore, is sufficient to exhaust the organism if it does 

 not find in the alimentation the new elements by which it 

 is reconstructed. Of this unceasing necessity of repairing 

 the loss which the organs sustain by the action of life, man 

 is imperiously reminded by hunger and thirst; hard condi- 

 tions of existence. He can support the first of these wants for 

 a time, which varies according to age and individual strength; 

 it is a sensation agreeable at first, but it soon becomes a 

 torture, a succession of atrocious pains, and moral and physi- 

 cal destruction follow. The annals of hunger are terrible in 

 science and in history; it has been called, with too much 

 reason, an evil counsellor, and he who has the means to 

 appease it each day should be thereby reminded of those 

 less fortunate than himself. 



