GENERAL ARRANGEMENT OF THE DIGESTIVE APPARATUS. 135 



matters taken into the stomach consist generally of all 1 varie- 

 ties of alimentary principles, and they are exposed to certain 

 mechanical processes in the mouth and alimentary canal, and 

 to the action of various secreted fluids. 



In the mouth, the food is divided, as the occasion de- 

 mands, by the incisor teeth, and is then passed, by the action 

 of the cheeks and tongue, between the molars, where it is sub- 

 jected to mastication. During this process it is mixed with 

 the various fluids which compose the saliva, and becomes more 

 or less coated with the tenacious secretions of the mucous 

 follicles of the buccal cavity. It is, or should be, reduced 

 in the mouth to a pultaceous mass, with which the saliva, 

 particularly that from the parotid gland, is thoroughly incor- 

 porated; while the secretion of the submaxillary and the 

 sublingual gland, being more viscid, has a greater tendency 

 to coat the exterior. 



By the action of the tongue, the alimentary bolus, after 

 mastication, is passed back to the pharynx, where, by the 

 successive action of the constrictor muscles, it is forced into 

 the cesophagus. This tube leads from the pharynx to the 

 stomach, and is provided with thick muscular walls, by the 

 contraction of which the food is passed into this cavity, which 

 serves at once as a receptacle for the food, and an important 

 active organ in digestion. 



The stomach is covered externally by the general perito- 

 neal covering of the abdominal organs. It is provided with 

 a mucous membrane, which secretes the gastric juice and ab- 

 sorbs the water with inorganic and other principles in solu- 

 tion. The stomach also has muscular walls, composed of un~ 



In this he only has reference to the action of the stomach , but the food passes 

 gradually from this organ into the intestinal canal, and the digestion is then 

 completed very rapidly. In many instances, after a good breakfast, Dr. Beau- 

 mont found the stomach empty in less than two hours ; but it sometimes required 

 more than four hours to dispose of the food taken at dinner. In later observa- 

 tions on St. Martin, in 1856, by Prof. F. G. Smith, of Philadelphia, it is stated 

 that food was never found in the stomach for more than two hours. (Experi- 

 ences sur la Digestion. Journal de la Physiologic, Paris, 1858, tome i., p. 146.), 



