in DIGESTION IN THE MOUTH AND STOMACH 193 



of the hydrochloric acid. This explains how the movements arise 

 and are kept up in the greater part of the stomach. 



The rhythmical movements of the pyloric antrum follow a 

 different course, in consequence of the same mechanical and 

 chemical stimuli. The food which fills and distends this region 

 suppresses the rhythmical movements by the acidity of the juice 

 with which it is saturated and the solid particles which it contains, 

 obstructs the pyloric orifice, and produces antiperistaltic waves, 

 which carry the food back towards the middle and fundus of the 

 stomach. The pyloric antrum thus contributes to the churning up 

 and mixing of the ingesta, which is a necessary condition in order 

 that they may be saturated with the secretion, and digested. 



At a certain stage in digestion the motor processes of the 

 stomach undergo an important modification. The solid con- 

 stituents of the food-stuffs are almost entirely dissolved, or at any 

 rate the mechanical effects of contact are much diminished, and 

 the acidity of the chyme reduced, on which the antiperistaltic 

 motions of the antrum subside, and it resumes the rhythmic 

 (systolic and diastolic) movements proper to it, while the tonic 

 spasm of the sphincters or pyloric valve ceases. Then at each 

 revolution of the antrum there is a little spurt of chyme into the 

 duodenum, synchronous with the opening diastole of the pyloric 

 orifice, as has often been observed directly in duodenal fistulae. 



There is thus, according to Ducceschi, a complete correspondence 

 between the chemical and dynamical functions of the stomach, 

 which justifies the assumption that (like the adult heart, according 

 to Kronecker) it possesses a nervous, self -steering, regulating 

 apparatus, for its functions as a whole (infra). 



Moritz (1901) has recently investigated the influence of the 

 nature of the food-stuffs on the rate of gastric evacuation in dogs 

 with duodenal fistulae and in man. The experiments on man 

 (principally on Moritz himself) were conducted as follows : Some 

 time after a test meal of known quantity and quality, a measured 

 amount of a known solution of some chemical product which can 

 be readily estimated and is not normally present in the ingesta, 

 was introduced into the stomach by the sound. After thoroughly 

 mixing the liquid with the gastric contents, by introducing air 

 into the stomach and violently shaking the body, a portion of the 

 mixture was drawn out again by the sound. From the lowered 

 concentration of the test substance (usually glucose), it was easy 

 to determine the quantity left behind in the stomach. Moritz 

 found that the mechanical consistency of the food was an essential 

 factor in the evacuation of the stomach. The gastric contents are 

 not passed on into the intestine in the form of solid pieces, nor 

 exclusively in the fluid state, but largely in the form of pulp. 

 Fluid foods (broth) are, however, more rapidly evacuated than 

 thick soups or sops. 



VOL. II 



