THE PERISTALSIS OF THE STOMACH 375 



fundus. After several minutes, i.e., when the secretion of alkaline bile and 

 pancreatic juice into the duodenum is well established, the pyloric sphincter 

 will relax more often to allow fluid food to pass to the duodenum, but when 

 the more solid particles come up against the sphincter it promptly 

 contracts and remains so for some time. Toward the completion of digestion 

 even solid undigested particles are carried on into the intestine. 



Hunger Contraction. Our 

 present knowledge of the charac- 

 ter and nervous regulation of the 



peristaltic contractions of the f ]^^ J ''A.M. 



stomach has been recently immeas- 

 urably advanced by the work of 

 Carlson. His studies have been on 

 man, with and without gastric 

 fistula, and on dogs. As a result 

 there can no longer be doubt that 



the sensation of hunger is attended ( ^ / ] 12 M . 



with characteristic contractions of 

 the empty stomach. Carlson's 

 studies of the contractions of the 

 empty stomach has established a 

 number of points in the nervous 



control. For example, the vagus 



, . . a 



nerves have a tonic influence over 



the organ, and their section " leaves 



the empty stomach on the whole 



permanently hypotonic." This 



control does not readily yield to 



the usual reflexes. The splanchnic 



nerves are, on the other hand, in- ( ) ^/ 5P.M. 



hibitory for the stomach. It is 



through this channel that the 



psychic and other reflexes act to FlG> 262. Outlines of the Roentgen-ray 



control the organ. Carlson studied Shadows of the Stomach Content as Digestion 



. , , Progresses. (Cannon.) 

 the phenomena in dogs which had 



both the vagi and the splanchnics sectioned. The stomach thus isolated 

 manifests the usual hunger peristalses and often "the hunger contractions 

 are identical in rate and character with those of the intact stomach in normal 

 (strong) tonus." This indicates that "the primary stimulus to these con- 

 tractions is not to be sought in the extrinsic nerves." It follows therefore 

 that the extrinsic nerves are merely regulative and modifying for the con- 

 tractions of the otherwise automatic organ. Of the two mechanisms, the 

 vagus is the more vital and least readily disturbed in its control. 



