MOVEMENTS OF THE STOMACH 285 



opening. The path lies through the cord as far as the tenth thoracic root, then 

 through the splanchnics. Inhibitory centers for the antrum are present in the 

 corpora quadrigemina ; and opening of the pylorus can be induced from the 

 olivary body over a pathway which runs through the cord. The dilator nerve 

 of the cardia under all circumstances proves to be a closing nerve for the pylorus. 

 Opening of the cardia and contraction of the pylorus occur simultaneously. 

 Langley finds inhibitory fibers for the pylorus also in the vagus. 



B. EVACUATION OF THE STOMACH 



When the stomach contents have been changed by the united action of the 

 gastric juice and the movements of the stomach into a gruelly mass known 

 as chyme, the object of gastric digestion is fulfilled; the pylorus is opened 

 and the chyme is forced into the intestine. 



The length of time the food is retained in the stomach depends to a great 

 extent upon the kind of food eaten. In dogs having a duodenal fistula, Moritz 

 has shown that pure fluids (water and uncoagulated milk) leave the stomach 

 very quickly. With coagulated milk the evacuation is considerably slower. 

 It is longest of all with the solid foods (meat, sausage). The consistency 

 of the stomach contents therefore determines primarily when the food will 

 be evacuated. But its chemical properties also are of considerable importance 

 in this respect. The experiments of Moritz upon himself tended to show that 

 water, weak salt solutions, and bouillon leave the stomach very quickly, but 

 water containing C0 2 , weak acid solutions, milk and beer remain considerably 

 longer. If meat or bread be eaten the expulsion of water ingested at the 

 same time is delayed considerably. 



[Cannon fed fat, carbohydrate and proteid foods, uniform in amount (25 c.c.) 

 and consistency and mixed with a small quantity of subnitrate of bismuth, to 

 cats, and with the aid of the fluoroscope observed the rate of their discharge 

 from the stomach. He found that fats remain longest in the stomach, proteids 

 next, and carbohydrates a very short time. When carbohydrates and proteids 

 were mixed in equal parts, the mixed food did not leave the stomach so slowly 

 as proteids alone or so rapidly as carbohydrates alone. Fat mixed in equal 

 amounts with proteids and with carbohydrates caused both these to be discharged 

 more slowly than when each was fed alone. ED.] 



Even with a diet of firm consistency, small portions having the consistency 

 of gruel are forced into the duodenum as they are formed, and thus the 

 evacuation of the stomach goes on gradually. It has been shown further that 

 the pylorus closes and the expulsive movements of the stomach cease tem- 

 porarily when a certain portion of the contents has been emptied (Hirsch, 

 v. Mering) . Not only the degree of fullness, but the reaction of the intestinal 

 contents is of importance in this connection. A slight stream of HC1 or pure 

 gastric juice poured steadily through a fistula into the duodenum, will cause 

 a soda solution previously introduced into the duodenum to be kept there 

 for an indefinite time. A soda solution poured into the duodenum in the 

 same way has no such effect. From this it follows that each outflow of 

 stomach contents into the intestine stops further evacuation until the HC1 

 of the gastric juice if neutralized by the alkaline fluids of the intestine 

 (Pawlow). 



