CH. XXXIV.] 



THE SUCCUS ENTERICUS 



523 



may be no formation of laevo-rotatory substances. The enzyme 

 in the juice which converts maltose into dextrose is called maltase ; 

 and that which acts upon lactose is called lactase. 



Up till a few years ago little or nothing was known regarding 

 the action of the intestinal juice beyond this, but investigations 

 published since that time have altered this state of things, and in the 

 light of these the succus entericus is seen to be a juice of the highest 

 importance. 



Pawlow was the first to show that one of its main actions is to 

 reinforce and intensify the action of the pancreatic juice, especially 

 in reference to its proteolytic power. Fresh pancreatic juice has 

 practically no digestive power on proteins. Claude Bernard, the 

 earliest to study the pancreatic secretion, entirely missed its tryptic 

 action. On standing, the juice very slowly acquires proteolytic 

 activity. Yernon has shown that much the same is true for extracts 

 of the pancreas. There is no doubt that what the fresh juice con- 



II 



FIG. 360. Diagram of intestinal fistula. I., Thiry's method ; II., Vella's method. A, Abdominal wall ; 

 B, intestine, with mesentery ; C, separated loop of intestine, with attached mesentery. 



tains is trypsinogen, and this is slowly transformed into the active 

 enzyme trypsin. 



If fresh pancreatic and intestinal juices are mixed together, the 

 result is a powerful proteolytic mixture, though neither juice by itself 

 has any proteolytic activity. 



Pawlow speaks of the substance in the intestinal juice which has 

 this action as an "enzyme of enzymes," and has named it entero- 

 kinase. 



Starling, like Pawlow, worked with dogs, and has confirmed his 

 main results. A valuable contribution to the same subject has also 

 been made by Hamburger. He has had the unusual opportunity of 

 examining human succus entericus. It became necessary in a patient 

 for surgical reasons to isolate a loop of the small intestine, and this 

 loop continued to discharge intestinal juice to the exterior for some 



