DIGESTION. 



81 



sequent loss of power, which attend the working of the 

 most perfect machinery of man's invention. 



3. General Plan of Digestion. The great change 

 which food undergoes in digestion is essentially a reform- 

 ing process, reducing articles of 



diet, which are at first more or 

 less solid, crude, and coarse, to 

 a liquid and finely comminuted 

 condition, suitable for absorption 

 into the blood. The entire pro- 

 cess of digestion takes place in 

 what is called the alimentary 

 canal, a narrow, tortuous tube, 

 about thirty feet in its entire 

 length. This canal begins in 

 the mouth, extends thence down- 

 ward through the gullet to the 

 stomach (a receptacle in which 

 the principal work of digestion 

 is performed), and thence onward 

 through the small and large in- 

 testines'. 



4. The stomach and intestines 

 are situated in the cavity of the 



attfomen (Fig. 16, C, and Fig. 22), FlG 16 ._ SECTION op THE TRUNK 



and OCCUpy about two-thirds of SHOWING THE CAVITIES OP THE 

 . , rf., , . . . , ., CHEST AND ABDOMEN. 



its space. The action to which the A< C a V it, y of chest ; 

 food is subjected in these organs c' Abffi5? ; 

 is of two kinds mechanical and D * E ' Spinal bolumn - 

 chemical. By the former it is crushed, agitated, and car- 

 ried onward from one point to another; by the latter it is 

 changed in form through the solvent power of the various 

 digestive juices. 



3. Change of food in digestion? Process of digestion? Describe the alimen- 

 tary canal. 



4. Situation of the stomach and intestines ? Action of the food ? Mechanical 

 action ? Chemical ? 



4* 



