INFLUENCE OF THE NERVOUS SYSTEM. 293 



dogs which, had fistulous openings into their stomachs, 

 saw that on the instant of dividing their pneumogastric 

 nerves, the process of digestion was stopped, and the 

 mucuous membrane of the stomach, previously turgid with 

 blood, became pale, and ceased to secrete. These, how- 

 ever, and the like experiments showing the instant effect 

 of division of the pneumogastric nerves, may prove no 

 more than the effect of a severe shock, and the fact that 

 influences affecting digestion may be conveyed to the 

 stomach through those nerves. From other experiments 

 it may be gathered, that although, as in M. Bernard's, 

 the division of both pneumogastric nerves always tem- 

 porarily suspends the secretion of gastric fluid, and so 

 arrests the process of digestion, and is occasionally followed 

 by death from inanition ; yet the digestive powers of the 

 stomach may be completely restored after the operation, 

 and the formation of chyme and the nutrition of the animal 

 may be carried on almost as perfectly as in health. 



In thirty experiments on Mammalia, which M. Wern- 

 scheidt performed under Miiller's direction, not the least 

 difference could be perceived in the action of narcotic 

 poisons introduced into the stomach, whether the pneu- 

 mogastric had been divided on both sides or not, provided 

 the animals were of the same species and size. It appears, 

 however, that such poisons as are capable of being 

 rendered inert by the action of the gastric 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 divided the pneumogastric nerves, a 

 dose of emulsine, and half an hour afterwards a dose of 

 amygdaline, 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 sub- 



