496 



DIGESTION IN THE INTESTINES 



[CH. XXXII. 



sewn up, and the other stitched to the abdominal wound, and so a 

 cul-de-sac from which the secretion can be collected is made. The 

 continuity of the remainder of the intestine is restored by fastening 

 together the upper and lower portions of the bowel from which the 

 loop has been removed. Vella's method resembles Thiry's, except that 

 both ends of the loop are sutured to the wound in the abdomen. Fig. 

 399 illustrates the two methods. 



The succus entericus possesses to a slight extent the power of con- 

 verting starch into sugar. Its best known action is due to a ferment 

 called invertin, which inverts saccharoses that is, it converts cane 

 sugar and maltose into glucose. The original use of the term " inver- 

 sion " has been explained on p. 390. It may be extended to include 

 the similar hydrolysis of other saccharoses, although there may be no 



II 



FIG. 399. 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. 



formation of levo-rotatory substances. There are probably numerous 

 inverting ferments, each of which acts on a different saccharose. 



Up till a year or two ago little or nothing was known regarding 

 the action of the intestinal juice beyond this, but investigations 

 published quite recently have, however, altered this state of things, 

 and in the light of these the succus entericus appears 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 proteids. 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- 

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

 enzyme trypsin. 



