The Digestion of Food 



109 



The gastric juice has no action on starchy foods, neither 

 does it act on fats, except to dissolve the albuminous walls 

 of the fat cells. The fat itself is thus set free in the form 

 of minute globules. 



/ 164, Passage of the Food into the Intestines. The con- 

 tents of the stomach now assume the appearance and 

 the consistency of a thick soup, 

 usually of a grayish color, known 

 as chyme. 



After a variable time, from 

 one to four hours, the chyme 

 begins to move on in succes- 

 sive portions into the next part 

 of the alimentary canal. The 

 ring-like muscles of the pylorus 

 relax at intervals to allow the 

 muscles of the stomach to force 

 the partly digested mass into the 

 small intestines. This action is 

 frequently repeated, until even 

 the indigestible masses which the gastric juice cannot break 

 down are crowded out of the stomach into the intestines. 

 From three to four hours after a meal the stomach is again 

 quite emptied. ^SL 



A certain' amount of this semiliquid mass, especially 

 the peptones, is at once absorbed, making its way through 

 the delicate vessels of the stomach into the blood current. 

 * 165. The Small Intestine. At the pyloric end of the 

 stomach the alimentary canal becomes again a slender 

 tube, about twenty feet long, called the small intestine. It is 

 divided, for convenience of description, into three parts. 



The first part is called the duodenum, because it is about 

 twelve fingers' breadth long, that is, about eight inches. 



FIG. 53. Pits in the Mucous 

 Membrane of the Stomach, 

 and Openings of the Gastric 

 Glands. 

 (Magnified 20 diameters.) 



