VOMITING. 205 



continuous rhythm ; and the cardiac part, which is an active reser- 

 voir, pressing out its contents a little at a time as the antral 

 mechanism is ready to receive them. 



Effect of the Movements of the Stomach upon the Food. The 

 experiments of Cannon demonstrate, in the cat at least, that the 

 idea of Beaumont that there is what may be called a circulation 

 of food from the cardia along the greater curvature to the pylorus, 

 and back along the lesser curvature, and that of Brinton that there 

 are peripheral currents from the cardia along the walls of the 

 stomach to the pylorus, and that these currents then unite and 

 come back to the cardia as an axial current, are incorrect. What 

 has been actually observed by Cannon shows conclusively that as 

 the constriction-waves approach a given portion of food, this latter 

 is pushed forward in the direction of the pylorus, but not moving 

 as fast as the wave, the constriction overtakes it, and as it passes 

 it pushes the food backward, for in this direction is the least 

 resistance ; the next wave pushes it forward a little further than 

 the preceding one, and as it passes again it is pushed backward, 

 but all the time it is making headway, though slowly, for the 

 progress exceeds the backward movement. This to-and-fro move- 

 ment is more marked in the antrum, where the waves are deep, 

 than in the middle region. 



On different occasions the portions of the food under observa- 

 tion have occupied from nine to twelve minutes in passing from 

 where the waves first affected them to the pylorus i. e., on the 

 way they were moved back and forth by more than fifty con- 

 strictions. 



When the pylorus is closed, the food being pushed forward by 

 the advancing constrictions, which are here very deep, and not 

 being able to escape into the duodenum, is squirted back through 

 the constricted ring. This process is repeated again and again 

 until the sphincter relaxes and the fluid parts pass out, or if not 

 rendered liquid pass into the duodenum later in a solid condition. 

 The solid portions then remain in the antrum, to be here acted 

 upon by the gastric juice, and to be subjected to the tireless rubbing 

 of the muscular coat. 



In the above resume we have used the language of the experi- 

 menter in describing his observations, condensing it where possi- 

 ble, but endeavoring not to alter his interpretation of the experiments. 



The researches of Pawlow lead to the conclusion that the relax- 

 ation of the sphincter pylori is due to the contact of free hydro- 

 chloric acid, and not to any mechanical action of the food. 



Vomiting 1 . The act of vomiting consists in an expulsion of 

 the contents of the stomach through the esophagus and the mouth. 

 Before the expulsive act takes place there are commonly nausea 

 and an increased secretion of saliva. Then a deep inspiration 

 occurs, caused by the descent of the diaphragm ; the glottis is 

 closed by the contraction of the arytenoid and the lateral crico- 



