56 DIGFSTTON. 



12. The superior opening ot this tube is the mouth ; it is 

 through it that ibod enters the digestive cavity. The inferior 

 opening, called anus, is destined as an outlet to matters unfit for 

 nutrition, which are separated from the food by digestion. 



13. In quadrupeds and most other animals, we distinguish, in 

 this alimentary tube, diverse portions, the uses of which are diffe 

 rent; they are: 



1st. The mouth. 



2nd. The pharynx or swallow 



3rd. The (Esophagus. 



4th. The Stomach. 



5th. The Intestine. 



1 4. Other organs, or instruments, also concur to effect the diges- 

 tion of food, and constitute, with the tube of which we have just 

 spoken, the digestive apparatus ; the principal are: 



1st. The teeth destined to divide and grind the food. 



2nd. Certain glands, such as the liver and salivary glands, 

 serve to form the humors, which act upon the food in order to 

 determine its digestion. 



3rd. Of particular vessels destined to pump into the intes- 

 tine the nutritious juices, produced by digestion, and to mix them 

 with the blood. 



In short we might consider as being in some sort auxiliary to 

 the digestive apparatus, certain organs with which certain animals 

 seize their food and introduce it into the mouth ; but these instru- 

 ments principally serve other purposes and do not really belong 

 to the apparatus of digestion. 



15. The process of digestion is very complicated, and is made 

 up of several phenomena or distinct acts, which take place in 

 different parts of the digestive apparatus, and which have, for 

 instrument?, particular organs. 



16. These phenomena are: 



1st. The prehension of aliments 



2nd. Mastication. 



3rd. Insalivation. 



4th Deglutition 



5th Chymiflcation, or stomach-digestion. 



6th. Chylification, or intestinal digestion. 



7th. Absorption of chyle. 



12. What are th termin itions qf the digestive tube? 



13. What arv the different po lions of the alimentary canal 1 



] I. What other organs beldng to the digestive apparatus? What is the 

 use of t'.e teeth 1 



!;>. Is the process of digestion confined to the stomach exclusively ? 

 1 6. What are the several acts r phenomena which constitute digestion 



