THE DIGESTION OF FOOD 115 



The chief use of the bile is to help digest the fatty foods 

 upon which the gastric juice does not act. The bile also 



FIG. 74. The Liver seen from Below and Behind. 



A and B, smaller lobes of the liver ; C, portal vein ; D, hepatic artery ; E, inferior 

 vena cava ; F, trunk of left hepatic vein ; G, hepatic vein. 



contains materials separated from the blood which are of no 

 further use to the body and which must be cast out before 

 they do mischief. 



Experiment 36. To show the action of bile on fats. Mix three 

 teaspoonfuls of bile 1 with a half teaspoonful of sweet oil. Shake 

 well, and keep the tube in a water bath at about 100 F. A very 

 good emulsion is obtained. 



1 Obtain from the butcher some ox bile. Note its bitter taste, peculiar 

 odor, and greenish color. It is alkaline or neutral to litmus paper. Pour 

 it from one vessel to another, and note that strings of mucus (from the 

 lining membrane of the gall bladder) connect one vessel with the other. It 

 is best to precipitate the mucus by acetic acid before making experiments, 

 and to dilute the clear liquid with a little distilled water. 



