226 PHYSIOLOGY OF ALIMENTATION. 



to a free secretion of pancreatic juice. This does not prove, 

 however, that the pancreas can be directly excited by this 

 means, for to tempt a hungry dog is to excite a gastric secre- 

 tion, and the acid flow produced in this way might readily be 

 the real excitant of the pancreatic flow. Two facts, however, 

 point strongly in favor of the existence of a psychic secretion 

 of pancreatic juice. First, tempting a dog with food or 

 sham feeding will cause a quiescent pancreas to become 

 active even when a gastric fistula allows the escape of the 

 gastric juice from the stomach as soon as formed; secondly, 

 the latent period marking the beginning of secretion from the 

 stomach and the pancreas is different in the two cases. An 

 acid flow begins from the stomach five to ten minutes after 

 the beginning of sham feeding. The pancreas begins to 

 secrete after two to three minutes. If the acid and not a 

 true psychic element were responsible for the secretion of 

 pancreatic juice the pancreas should not become active until 

 after the gastric flow has commenced. 



Water also acts as an excitant of the pancreas. When 

 150 c.c. of water are introduced unnoticed into the stomach 

 of a dog the pancreas begins to secrete, or augments its flow 

 two or three minutes after the water has entered the stomach. 

 If the experiment is properly performed this amount of water 

 does not excite a flow of gastric juice, so that a secretion of 

 pancreatic juice secondary to a secretion of gastric juice is 

 out of the question here. 



. Meat extracts, which were found above to be such good ex- 

 citants of the gastric glands, are no more effective in the case 

 of the pancreas than an equal amount of water. 



What has been said in this section regarding the influence 

 of acids, food, etc., on the qualitative and quantitative com- 

 position of the pancreatic juice in the dog seems to hold 

 without modification for the human being. As evidence in 

 this direction we may cite the experiments of GLAESSNER 1 on 



1 GLAESSNER, Zeitschrift fur physiologische Chemie, 1904, XL, p. 46f 



