236 DIGESTION. 



fluid, may, if taken into the stomach shortly after division of 

 both pneumogastric nerves, produce their poisonous effects; in 

 consequence, apparently, of the temporary suspension of the 

 secretion of gastric fluid. Thus, in one of his experiments, M. 

 Bernard gave to each of two dogs, in one of which he had di- 

 vided the pneumogastric nerves, a dose of emulsin, and half 

 an hour afterwards a dose of amygdalin, substances which 

 are innocent alone, but when mixed produce hydrocyanic acid. 

 The dog whose nerves were cut, died in a quarter of an hour, 

 the substances being absorbed unaltered and mixing in the 

 blood; in the other, the emulsin was decomposed by the gas- 

 tric fluid before the amygdalin was administered; therefore, 

 hydrocyanic acid was not formed in the blood, and the dog 

 survived. 



The influence of the pneumogastric nerves over the secretion 

 of gastric fluid has been of late even more decidedly shown by 

 M. Bernard, who found that galvanic stimulus of these nerves 

 excited an active secretion of the fluid, while a like stimulus 

 applied to the sympathetic nerves issuing from the semilunar 

 ganglia, caused a diminution and even complete arrest of the 

 secretion. 



The influence of the nervous system on the movements of the 

 stomach has been often seen in the retardation or arrest of these 

 movements after division of the pneumogastric nerves. The 

 results of irritating the same nerves were ambiguous ; but the 

 experiments of Longet and Bischoff have shown that the dif- 

 ferent results depended on whether the stomach were digesting 

 or not at the time of the experiment. In the act of digestion, 

 the nervous system of the stomach appears to participate in 

 the excitement which prevails through the rest of its organiza- 

 tion, and a stimulus applied to the pneumogastric nerves is felt 

 intensely, and active movements of the muscular fibres of the 

 stomach follow; but in the inaction of fasting, the same stimu- 

 lus produces no effect. So, while the stomach is digesting, the 

 pylorus is too irritable to allow anything but chyme to pass; 

 but when digestion is ended, the undigested parts of the food, 

 and even large bodies, coins, and the like, may pass through it. 



Digestion of the Stomach after Death. 



If an animal die during the process of gastric digestion, and 

 when, therefore, a quantity of gastric juice is present in the 

 interior of the stomach, the walls of this organ itself are fre- 

 quently themselves acted on by their own secretion, and to 

 such an extent, that a perforation of considerable size may be 

 produced, and the contents of the stomach may in part escape 



