HOW THE ANIMAL LIVES 221 



bowels, and transforms their fatty contents into an 

 emulsion which penetrates an animal membrane, 

 and is absorbed with great rapidity. 



397. Bile has, besides, a limited power of 

 changing starch into sugar. It is also useful in 

 carrying waste matters out of the body. 



398. Pancreatic juice is poured into the in- 

 testines by a canal which in certain animals unites 

 with the bile duct. It contains at least four 

 different ferments : (a) Amylopsin, which, at 

 the body temperature, rapidly transforms starch 

 and even gum into sugar, thus completing any 

 imperfect work of the saliva ; (6) trypsin, 

 which, in an alkaline liquid, changes nitroge- 

 nous matters into peptones, thus finishing any 

 imperfect work of the stomach ; (c) a milk -cur- 

 dling ferment. 



399. The pancreatic juice, as a whole, acts 

 like the bile in causing fats to form emulsions. 

 It even breaks up the fats into fatty acids and 

 glycerin. 



400. Intestinal juice is a complex mixture of 

 the different secretions already named, together 

 with the products of the glands of the intestinal 

 walls. The secretions of these walls act like 

 pancreatic juice, only less powerfully. 



401. As a whole, the digestive agents thrown 

 into the intestines cover the whole field of di- 

 gestion, and largely make up for any defective 



