GASTRIC DIGESTION. 367 



might be called the am}'lolytic period of digestion, is absent. This 

 amylolytic period lasts for about three or four hours, including, of 

 course, the half-hour or hour occupied by the meal. The duration is, 

 however, longer in the cardiac sac than in the fundus and pyloric 

 portions of the stomach, where it becomes gradually converted into 

 what might be termed the proteolytic period, in which the proteids 

 become converted into peptones. 



The digestion of proteids in the hog is first rendered possible 

 through the presence of lactic acid, During this stage of proteolysis 

 the digestive processes differ in the cardiac and pyloric portions of the 

 stomach, indicating that for several hours a well-marked difference 

 exists between the contents of these different regions of the stomach, in 

 the former of which only lactic acid and in the latter both hydrochloric 

 and lactic acids are present. This fact, for which we are also indebted 

 to Ellenberger and Hofmeister, is in opposition to the generally accepted 

 views as to the rapid diffusion and mixing of the gastric contents. 



The second digestive period, in which, while the cardiac extremity 

 is still digesting starch, the pyloric half is digesting albumen, begins 

 at about the third or fourth hour of digestion, and may continue from 

 nine to twelve hours. 



In the third period the digestion of starch ceases, from the great 

 development of hydrochloric acid, although it should be remembered 

 that up to the fourth hour of gastric digestion the cardiac fluid is still 

 capable of converting starch into sugar. 



It thus would appear that digestion in the stomach of the hog con- 

 tinues from one meal to the other, although in a moderate meal part of 

 the gastric contents maj^ pass into the intestine three or four hours after 

 eating; but part, nevertheless, remains in the stomach, and may be 

 found there even thirty-six hours afterward. 



These results further show that the degree of mixing of the con- 

 tents of the stomach produced by the gastric movements is by no means 

 complete, the first quantities being gradually pushed on toward the 

 P3*lorus by those coming afterward. The degree of acidity of the gastric 

 contents gradually increases. While at first alkaline, it gradually 

 increases in acidity so that three hours after the meal 0.07 per cent, acid 

 may be recognized in the left half of the stomach and 0.2 per cent, in 

 the right half. The acid within the left half of the stomach then com- 

 mences to increase, until finally it may amount to 0.3 per cent. When 

 the meals rapidly follow each other gastric digestion is interrupted, and 

 the undigested portion is forced into the intestine, undergoing digestion 

 there by means of the intestinal digestive fluids. As a consequence, 

 in large meals the amylolytic period is increased and the proteolytic 

 period decreased, while the degree of acidity more slowly approaches a 



