REGULATION OF THE PANCREATIC SECRETION. 227 



his patient with a fistula of the pancreatic duct. GLAESSNER 

 found that the amount of juice secreted in the unit of time 

 was greatly increased soon after his patient took food. 

 Whereas under ordinary circumstances 10 to 15 c.c. flowed 

 from the fistula per hour, 38 c.c. were obtained in the first 

 hour after a meal, 34 c.c. in the second, and 46 c.c. in the 

 fourth. From this hour on the flow steadily decreased 

 until at the end of the eighth it had fallen to its original level. 

 It is evident, therefore, that the curve representing the rate 

 of secretion in the human being is similar to that which has 

 been described for dogs. 



The amount of lipolytic, amylolytic, and proteolytic fer- 

 ment in the unit volume of pancreatic juice GLAESSNER also 

 found to vary with the taking of food. Between meals this 

 was least, while the slow rise which began during the first 

 or second hour after eating was found to attain its maximum 

 about the fourth, when it fell once more in the following four 

 hours to its original level. The alkalinity of the juice was 

 also found to increase after the taking of food. While with 

 phenolphthalein as indicator 1 c.c. of decinormal acid was re- 

 quired to neutralize 10 c.c. of pancreatic juice between meals, 

 it required 5 c.c. of the acid to neutralize the same amount of 

 juice obtained during the fourth hour after a meal. 



The presence of an acid in the duodenum seems to increase 

 the pancreatic flow in a human being just as in a dog. 

 GLAESSNER found that the introduction of several hundred 

 cubic centimeters of a weak hydrochloric acid into the 

 stomach of his patient was followed almost immediately by an 

 increased pancreatic flow which attained its maximum by the 

 end of the first hour, and fell to the original level once more 

 by the end of the second, as in the case of the dog. 



5. Pancreatic Secretin. In discussing the effect of acids 

 upon the pancreatic flow, no mention was made of the mechan- 

 ism by which this most powerful excitant of the gland accom- 

 plishes its results. PAWLOW believed that the gland was 

 excited through a nervous reflex, initiated by the effect of 



