364 DIGESTION 



action of the pancreatic juice is also favoured by the bile, and in 

 about the same degree as its proteolytic effect. Although bile some- 

 times exerts by itself a feebly amylolytic action, this is not to be 

 included among its specific powers, for a diastatic ferment in small 

 quantities is widely diffused in the body. 



The addition of bile or bile-salts to a gastric digest causes the 

 precipitation of any unaltered native protein, acid-albumin, albu- 

 mose, and pepsin. The precipitate, which is a salt-like compound 

 of protein with taurocholic acid, is redissolved when the liquid is 

 rendered alkaline, and therefore in excess of bile, or of a solution of 

 bile- salts, but the pepsin has no longer any power of digesting 

 proteins. Part of the bile-acids and bile-mucin is also thrown down 

 by the acid of the digest. It has been suggested that by thus 

 precipitating the constituents of the chyme which have not been 

 carried to the peptone stage bile prepares them for the action of the 

 pancreatic juice. But it is difficult to see how the precipitation of 

 a substance can prepare the way for its digestion, and it is more 

 probable that if any physiological value is to be given to this reaction, 

 it has the function of preventing the absorption of proteins which 

 have not been sufficiently split up. There is little doubt, however, 

 that the rendering of the pepsin inactive has physiological signifi- 

 cance, for pepsin exerts an injurious influence upon the ferments of 

 the pancreatic juice. In digestion, then, the bile has a twofold func- 

 tion, favouring greatly the activity of the pancreatic ferments, especially 

 the fat-splitting ferment, and aiding in establishing the conditions 

 necessary for the transition of gastric into intestinal digestion. 



Succus Entericus. This is the name given to the special secretion 

 of the small intestine, which is supposed to be a product of the 

 Lieberkiihn's crypts or intestinal glands. In order to obtain it pure, 

 it is of course necessary to prevent admixture with the bile, the pan- 

 creatic juice, and the food. This can be done by dividing a loop of 

 intestine from the rest by two transverse cuts, the abdomen having 

 been opened in the linea alba. The continuity of the digestive tube 

 is restored by stitching the portion below the isolated loop to the 

 part above it. One end of the loop is sewed into the lips of the 

 wound in the linea alba, and the other being closed by sutures, the 

 whole forms a sort of test-tube opening externally (Thiry's fistula). 

 Or both ends are made to open through the abdominal wound (Vella's 

 fistula). Another method is to make a single opening in the intes- 

 tine, and by means of two indiarubber balls, one of which is pushed 

 down, and the other up through the opening, and which are after- 

 wards inflated, to block off a piece of gut from communication with 

 the rest. Or several openings may be made at different levels in the 

 intestine, each being allowed to heal into a wound in the abdominal 

 wall. When pure juice is required it is collected from the lower 

 fistulae, while the upper fistulae are opened to permit the escape of the 



