204 GASTRIC DIGESTION 



peristaltic movements of the intestines, for which, indeed, they were 

 mistaken, as the nature of the case was not recognized during life. 



A peculiarity in the movements of the stomach which has been 

 repeatedly observed in the lower animals, particularly dogs and cats, 

 and in certain cases has been confirmed in the human subject is that 

 at about the junction of the cardiac two-thirds with the pyloric third, 

 there is a transverse band of fibres (the sphincter antri pylori) so firmly 

 contracted as to divide the cavity into two almost distinct compartments. 

 It has also been noted that the 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, the movements are more frequent, 

 vigorous and expulsive. 



As the result chiefly of the observations of Beaumont, the following 

 may be stated 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 

 begins, contractions of the muscular coat occur, which are at first slow 

 and irregular, but become more vigorous and regular as the process of 

 digestion advances. After digestion has become fully established, the 

 stomach usually is divided, by the firm and almost constant contraction 

 of an oblique band of fibres, into a cardiac and a pyloric portion (the 

 antrum pylori); 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 

 pyloric division they are intermittent and more expulsive. The effect 

 of the contractions of the stomach on the food contained in its cavity is 

 to subject it to a nearly uniform pressure in the cardiac portion, the 

 general tendency of the movement being toward the pylorus along the 

 greater curvature and back from the pylorus toward the great pouch 

 along the lesser curvature. At the constricted part which separates 

 the cardiac from the pyloric portion, there is an obstruction to the 

 passage of the food until it has been sufficiently acted on by the 

 secretions in the cardiac division to have become reduced to a pul- 

 taceous consistence. The alimentary mass then passes into the pyloric 

 division, and by a more powerful contraction than occurs in other parts 

 of the stomach, it is passed into the small intestine. The classical obser- 

 vations of Beaumont have been in the main confirmed by Hofmeister 

 and Schiitz, Cannon and others. 



The revolutions of the alimentary mass, thus accomplished, take 



