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NUTRITIVE FUNCTIONS DIGESTION. 279 



der ; m, cystic duct ; n, ductus communis, formed by the union of both; 

 o, the opening of this duct into the duodenum ; p, pancreatic duct ; q, 

 its opening into the duodenum ; r, jejunum; s, ilium; these constitute 

 the small intestines, and are about twenty-six feet in length, or five 

 times the length of the body ; *, termination of ilium in the coecum ; 

 u, superior fold of valve of colon ; v, inferior do. ; w, coecum ; x, ver- 

 miform process ; y, y, colon ; z, rectum. The coecum, colon, and 

 rectum, form the large intestines, and are about six feet in length ; the 

 coecum being about 4 inches long, and the same in diameter. The 

 arrows show the direction which the food takes in digestion. 



12. Hunger and thirst are sensations designed to teach us 

 the necessity of supplying those losses which the system is 

 constantly undergoing by the different secretions and excre- 

 tions, amounting to several pounds in the course of twenty, 

 four hours. The blood first feels the loss, and then the 

 solids, whose particles are continually taken up by the ab- 

 sorbents, and carried into the blood, and thus ejected from 

 the system ; and were not these losses supplied by the timely 

 introduction of food, the body would rapidly emaciate, till 

 death closed the scene. Hunger is supposed to be owing to 

 a peculiar affection of the nerves of the stomach ; for when 

 the nerve which goes from the brain to the stomach (the par- 

 vagum,) is divided, the sensation of hunger is lost, or at 

 least the appetite for food is destroyed. 



13. While the food is undergoing the process of mastica- 

 tion, that is, of being divided and ground down by the tee! 



it is thoroughly mixed with a quantity of saliva, amounting 

 it is supposed to between eight and ten ounces. The food 

 is thus brought into a condition to be easily swallowed, and 

 readily dissolved by the action of the stomach. It is very 

 important, therefore, that the food should be slowly chewed, 

 and reduced to as fine a state as possible in the mouth, in 

 order that digestion may be easy. Too great rapidity in 

 eating, probably lays the foundation of many cases of indi- 

 gestion. 



14. After the food has been sufficiently masticated, it is 

 carried down the aesophagus into the stomach, first by the 



