254 DIGESTION. 



contractions in the cardiac division are much less vigorous than near the pylorus ; the 

 stomach seeming simply to adapt itself to the food by a gentle pressure as it remains in 

 the great pouch, while, in the pyloric portion, divided off as it is by the hour-glass con- 

 traction above-mentioned, the movements are more frequent, vigorous, and expulsive. 

 We must again refer, however, to the observations of Beaumont for the only accurate 

 description of the movements of the stomach, as they take place during digestion in the 

 human subject. 



The experiments of Beaumont were generally made with the subject lying on the 

 right side, and the movements of the stomach were observed by following with the eye a 

 particular morsel of food as it passed along, or by introducing the bulb of a thermometer 

 into the organ and allowing it to move with the alimentary mass. It was invariably 

 found that the movements of the thermometer-bulb were the same as those observed by 

 identifying and following a particular portion of food. As the alimentary bolus enters 

 by the cardiac opening, it turns to the left, descends into the greater pouch, and follows 

 the greater curvature to the pyloric end. It then returns to the cardiac orifice by the 

 lesser curvature and takes again the same course as before. While these revolutions, so 

 to speak, of the alimentary mass are going on, the food is turned over and over, so that 

 it becomes intimately mixed with the digestive fluids and subjected to a certain amount 

 of trituration. This action is undoubtedly of great importance, as fresh portions of food 

 are thereby successively exposed to the action of the gastric juice, and the boluses, with 

 their particles agglutinated to a certain extent in the mouth, are disintegrated and pene- 

 trated with the gastric fluid in every part. 



A marked difference was observed between the movements in the cardiac and in the 

 pyloric portion. When the thermometer-bulb arrived at the contracted septum, which 

 was three or four inches from the pyloric end, it was at first stopped by the forcible con- 

 traction ; but, in a short time, there was a gentle relaxation which allowed it to pass, 

 when it was drawn quite forcibly for three or four inches toward the pyloric opening. 

 When in this portion of the stomach, the bulb was firmly grasped and made to undergo 

 a spiral motion ; and, if drawn forcibly out, it gave to the fingers the sensation of being 

 held by a strong suction force. As soon as relaxation occurs, the bulb is passed back to 

 the seat of stricture, and, when pulled through this, it moves freely in the great cavity. 

 Each one of these revolutions was found to occupy from one to three minutes. They 

 were slower at first than after digestion had been somewhat advanced. 



The mechanism of the movements of the stomach is easily appreciated when we con- 

 sider the number and varied direction of the fibres which form the muscular coat of the 

 stomach, and the fact that the stomach, when distended, is more or less displaced with 

 every movement of the diaphragm. It is easy to understand, also, how, in the pyloric 

 portion, where the muscular fibres are thickest and the cavity is elongated and compara- 

 tively small, the movements should be more vigorous and expulsive than in the rest of the 

 organ. We have already alluded to the fact that the movements of the stomach are 

 animated by the pneumogastric nerves and become arrested when both these nerves are 

 divided. 



As the result chiefly of the observations of Beaumont, the following may be taken as 

 a summary of the physiological movements of the stomach in digestion : 



The stomach normally undergoes no movements until food is passed into its cavity. 

 When food is received, at the same time that the mucous membrane becomes congested 

 and the secretion of gastric juice commences, contractions of the muscular coat begin, 

 which are slow and irregular during the commencement of stomach-digestion, but become 

 more vigorous and regular as the process advances. After digestion has become fully 

 established, the stomach is generally divided, by the firm and almost constant contraction 

 of a transverse band of fibres, into a cardiac and a pyloric portion ; the former occupying 

 about two-thirds, and the latter, one-third of the length of the organ. The contractions 

 of the cardiac division of the stomach are uniform and rather gentle ; while, in the 



