64 CTIYMIFICATION. 



61. The veil of the palate, by being raised up, and placed ob- 

 liquely against the posterior wall of the pharynx, forms beneath 

 the posterior nostrils, a sort of screen, which hinders the food 

 from mounting upwards, and entering the nose from behind, 

 during the act of swallowing. 



62. That the food may not enter the glottis, it closes at the 

 moment of deglutition, and, at the same time, the larynx is raised 

 up against the base of the tongue, a movement which forces a 

 valve situated above the glottis, and called epiglottis, ( Fiy, 21, ep.) 

 to fall and close the opening. 



63 Sometimes, however, deglutition not being properly effected, 

 the food penetrates into the larynx, and at once brings on a fit of 

 coughing : when this happens, it is said , " we swallow crosswise." 



64. The ces<tpkyus, or gullet, is continuous with the pharynx : 

 it is a long meVnbranous tube, which descends from the superior 

 part of the neck, behind the windpipe ; enters the thorax, passes 

 behind the heart and lungs, pierces the diaphragm, and terminates 

 in the stomach. 



65. The pharynx and oesophagus, are furnished with a layer 

 of fleshy fibres which are placed transversely, in rings, which, 

 contracting successively from above downwards, convey the ali- 

 mentary ball into the stomach. 



LESSON VI. 



FUNCTIONS OP NUTRITION. Stomach digestion, or chymijica- 

 tion. lutt'stinal digestion, or chyhftcation. Bile and liver. 

 Pancreas, and Pancreatic Juice. Large intestine, Absorption 

 of chyle. Chyliferuus vessels. Recapitulation of the function* 

 of nutrition. 



OF STOMACH DIGESTION, OR, CHYMIFICAT1ON. 



1. Food begins to be digested in the stomach ; it is there trans- 

 formed into chyme, and we give to this phenomenon the name 

 of stomach digestion, or chymification. 



61. What prevents the food from entering into the posterior nares? 



62. What hinders food from entering the glottis? 



63. What is the effect of food penetrating into the larynx ? 



64. What is the oesophagus? 



65. How is the alimentary ball conveyed into the stomach? 



-. Where does digestion commence? Into what is food changed in th 

 stomach ? What is the term applied to this change of food ? 



