218 FUNCTIONS OF BILE. 



the portal vein, nearly all of the material obtained by absorp- 

 tion from the digestive tube. The blood from the portal vein 

 is distributed through the liver. And from this blood the 

 liver manufactures at least two important substances, the bile 

 and the liver-starch, or Glyeogen. 



The bile is secreted all the time, but more actively during 

 digestion. The part made while digestion is not going on is 

 stored in the bile-sac. The functions of the bile are still 

 poorly understood. But the following are believed to be a 

 part of its work : 



1. It is believed to aid in emulsifying the fats. 



2. It is supposed to aid in the absorption of fat. 



3. The bile, to a certain extent, is waste matter; so the 

 liver is an organ of excretion as well as an organ of secretion. 



4. It is found that if, for any cause, the bile is prevented 

 from entering the intestine, constipation follows, and the con- 

 tents of the large intestine have a much more fetid odor than 

 usual. The bile itself readily putrefies ; hence it is concluded 

 that the bile has no positive antiseptic properties, but in some 

 indirect way retards putrefaction. 



The liver, from its size, ought certainly to be of great im- 

 portance in the body ; it is the largest gland in the body, and 

 receives one-fourth of the blood. 



The pancreatic juice acts on all the principal classes of 

 foodstuffs : 



1. A ferment in it called Amylopsin acts on starches, chan- 

 ging them to sugar, even more energetically than the ptyalin of 

 the saliva. 



2. Another constituent of pancreatic juice is Trypsin ; like 

 the pepsin of gastric juice, this ferment has the power of 

 cnanging proteids to peptones. 



3. The pancreatic juice also acts on the fats, in two ways : 

 (a) It emulsifies them, i.e., the fat is divided into exceed- 



