318 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



tion. In Beaumont's observations the movements of the pylorus are recorded 

 as following each other at intervals of two to three minutes, while upon dogs 

 similar movements are recorded as occurring from three to six times in a 

 minute. 



It will be seen that according to this description the movements occur in 

 two phases : first, the feeble peristaltic movement running over the fundus 

 chiefly on the side of the great curvature and resulting in pushing some of the 

 fundic contents into the antrum ; second, the sharp contraction of the sphincter 

 autri pylorici followed by a similar contraction of the entire musculature of the 

 antrum, both circular and longitudinal, the effect of which is to squeeze some 

 of the contents into the duodenum. It is possible that either of these phases, 

 but especially the first, might occur at times without the other, and in the first 

 phase it is probable that the longitudinal fibres of the stomach also contract, 

 shortening the organ in its long diameter and aiding in the propulsive move- 

 ment, but actual observation of this factor has not been successfully made. It- 

 can well be understood that a series of these movements occurring at short 

 intervals would result in putting the entire semi-liquid contents of the stomach 

 into constant circulation. The precise direction of the current set up is not 

 agreed upon, but it is probable that the graphic description given by Beaumont 

 is substantially accurate. A portion of this description may be quoted, as fol- 

 lows : " The ordinary course and direction of the revolutions of the food are, 

 first, after passing the oasophageal ring, from right to left, along the small 

 arch ; thence, through the large curvature, from left to right. The bolus, as it 

 enters the cardia, turns to the left; passes the aperture ; descends into the splenic 

 extremity, and follows the great curvature toward the pyloric end. It then 

 returns in the course of the small curvature." The average time taken for one 

 of these complete revolutions, according to observations made by Beaumont, 

 seems to vary from one to three minutes. 



It is possible, of course, that this typical circuit taken by the food may often 

 be varied more or less by different conditions, but the muscular movements 

 observed from the outside would seem to be adapted to keeping up a general 

 revolution of the kind described. The general result upon the food may easily 

 be imagined. It becomes thoroughly mixed with the gastric juice and any liquid 

 which may have been swallowed, and is gradually disintegrated, dissolved, and 

 more or less completely digested so far as the proteid and albuminoid constitu- 

 ents are concerned. The mixing action is aided, moreover, by the movements 

 of the diaphragm in respiration, since at each descent it presses upon the stomach. 

 The powerful muscular contractions of the antrum serve also to triturate the 

 softened solid particles, and finally the whole mass is reduced to a liquid or 

 semi-liquid condition in which it is known as chyme, and in this condition the 

 rhythmic contractions of the muscles of the antrum eject it into the duodenum. 

 The rhythmic spirting of the contents of the stomach into the duodenum has 

 been noticed by a number of observers by means of duodenal fistulas in dogs, 

 established just beyond the pylorus. It has been shown also that when the 

 food taken is entirely liquid water, for example the stomach is emptied in a 



