BILIARY AND INTESTINAL SECRETIONS. 247 



it, juice entirely incapable of digesting egg albumin is obtained. 

 This juice readily becomes active in this direction if a small 

 amount (a drop or two) of intestinal juice obtained from 

 an intestinal fistula in another animal is added to it. 



As to the nature of enterokinase but little is known at 

 present, for the substance cannot be obtained in even an 

 approximately pure state. Since it is readily destroyed at 

 comparatively low temperatures PAWLOW has looked upon it 

 as a ferment. This conception of enterokinase scarcely har- 

 monizes with the observations that have been made, which 

 indicate that a definite amount of enterokinase-containing 

 fluid can activate only a limited amount of pancreatic juice. 

 True ferments, it is well-known, act upon an infinite amount 

 of substance if only sufficient time is given. 



The secretion of enterokinase is not to be looked upon as 

 a function performed by the small intestine at all times. 

 Enterokinase appears and disappears from the juice poured 

 out by the upper portions of the small intestine in the same 

 way as the amount of bile poured into the duodenum is con- 

 trolled by such circumstances at the taking of food. In fact, 

 the secretion of enterokinase is connected with physiological 

 processes going on in the intestine in the same way as the 

 secretion of bile. When the small intestine is stimulated 

 mechanically it secretes a juice, but it is thin and watery and 

 contains practically no enterokinase. As soon, however, as 

 a few cubic centimeters of pancreatic juice are introduced 

 into the lumen of the intestine, the juice secreted becomes 

 rich in enterokinase. Boiled pancreatic juice does not have 

 this power. The secretion of the watery constituents and 

 of the enterokinase of the intestinal juice represent, there- 

 fore, different physiological processes. 



The idea that pancreatic juice obtained directly from the 

 pancreatic duct has no power to digest proteins contradicts 

 the views of a number of observers who have claimed that 

 the spleen furnishes at the height of digestion a substance 

 which is absorbed into the blood and through its action on 



