294 DIGESTION. 



stances being absorbed unaltered and mixing in the blood ; 

 in the other, the emulsine was decomposed by the gastric 

 fluid before the amygdaline 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 de- 

 cidedly 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 dimi- 

 nution 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 different results depended on whether 

 the stomach were digesting or not at the time of the experi- 

 ment. In the act of digestion, the nervous system of the- 

 stomach appears to participate in the excitement which 

 prevails through the rest of its organization, 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 stimulus 

 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 



