THE EMPTYING OF THE STOMACH. 165 



pyloric orifice and at the same time inhibits the propulsive movements 

 of the organ. The acid food mass allowed through by the pylorus 

 causes in turn an increased secretion of pancreatic juice, and is thus 

 gradually neutralised. It is only when this has been achieved that the 

 escape of a further portion of acid contents from the stomach is per- 

 mitted. This regulatory action prevents disorder in the progress of 

 digestion, and at the same time ensures regularity in the transition from 

 the acid gastric digestion to the alkaline intestinal. If it were other- 

 wise, and the acid contents of the stomach passed without control into 

 the duodenum, the bile, on mixing with it, might arrest or greatly 

 weaken the action of the pepsin, while the insufficient reduction of 

 acidity would hinder the activity of the pancreatic ferments. The 

 digestion of the food might thus, under certain circumstances, be 

 completely arrested. But as matters stand this cannot happen. The 

 injurious effect of pepsin upon intestinal digestion is arrested, while 

 owing to the neutralisation of the food mass, together with the entry of 

 those powerful excitants of the pancreatic juice, namely, the bile and the 

 succus entericus, the ferments of the pancreas are afforded the oppor- 

 tunity of unfolding their activities in the most unrestrained manner. 



Although, in the paper of Dr. Hirsch, clear and direct references are 

 made to the fact that acid and alkaline fluids pass from the stomach 

 into the duodenum at different rates, neither this author nor the other 

 investigators who have worked at the subject (v. Mering and Marbaix) 

 appreciated the nature of the acid reflex which regulates the passage of 

 the food contents into the intestine. On the contrary, they misinter- 

 preted it by thin king exclusively of a mechanical reflex discharged from 

 the duodenum and acting upon the pyloric orifice of the stomach. 



In other experiments (Dr. P. 0. /SWm'o&ic/i), which dealt with the move- 

 ments cf the stomach itself, the following phenomenon was observed by 

 us. In fasting animals, movements for emptying the stomach are from 

 time to time discharged, probably as the result of a psychic impulse. 

 If, now, without the animal perceiving it, neutral or alkaline solutions 

 (e.g., physiological saline, ^ per cent, solution of sodium bicarbonate, fluid 

 egg-albumen, or milk) be poured through the fistula into the stomach, the 

 fluids are all very rapidly that is, in the course of a few minutes largely 

 passed on into the intestine. When, however, the stomach happened to 

 be at rest to begin with, the fluids, introduced with the same precaution, 

 remained several minutes in it without moving from the spot. These 

 spontaneously occurring movements of the stomach can be repressed in 

 a purely psychic manner, if the dog for instance, be greatly roused by 

 the sight of food, or still better, if with an lesophagotomised animal a 

 sham feeding be carried out. Consequently, when an ingestion of food is 

 immediately to take place, or is actually happening, the evacuating 



