BILIARY AXD INTESTINAL SECRETIONS. 243 



same important function in fat digestion that the intestinal 

 juice serves through the enterokinase it contains in protein 

 digestion. 



3. Regulation of the Intestinal Secretion. In order to 

 obtain a collection of pure intestinal juice use is made of 

 THIRY'S classical fistula, or THIRY'S fistula as modified by 

 VELLA. An opening is made in the abdominal wall of an 

 animal, and a suitable loop of intestine is pulled out. Two 

 transverse cuts separate any desired length of the intestine 

 from the main portion of the tube, the continuity of which is 

 restored by an end-to-end anastomosis. The separated 

 loop of intestine is then closed at one end by a purse-string 

 suture, while the opposite end is sewed into the edges of the 

 wound. In this way a test-tube shaped piece of the bowel 

 is separated from the main body of the gut (THIRY fistula), 

 or both ends may be sewed into the abdominal wound when 

 we have the so-called THIRY-VELLA fistula. The artificial 

 production of all the most successful fistulae along the gastro- 

 intestinal tract is modelled after the original THIRY operation 

 on the small intestine. 



In the quiescent state of the animal practically no secre- 

 tion can be obtained from such an isolated loop of intestine. 

 As soon as food, such as starch paste, sugar, or peptone, is 

 introduced into the loop an increased secretion takes place. 

 Apparently, therefore, intestinal juice is secreted under 

 ordinary circumstances only by those portions of the gut 

 with which food is in contact, and not throughout its entire 

 length. The presence of food may cause a secretion either 

 through its mechanical or chemical properties. That mere 

 mechanical stimulation may be effective in causing a secre- 

 tion of intestinal juice is proved by the fact that the irritation 

 of a cannula in an intestinal fistula, a rubber ball, etc., all 

 lead to a secretion of juice. According to PAWLOW and his 

 co workers the intestinal juice obtained in consequence of 

 mechanical stimulation alone differs fiom that obtained by 

 chemical means. The former kind consists chiefly of water 



