100 STUDIES IN PHYSIOLOGY 



in a later chapter that all the blood from the stomach and 

 intestines passes through the liver on its way back to the 

 heart. If this blood contains more sugar than is needed, 

 the excess is left behind in the liver cells, where it is 

 changed to a kind of animal starch called gly'co-gen. When, 

 on the other hand, there is a lack of carbohydrates in the 

 blood, some of the supply in the liver is changed back to 

 sugar and is taken up again by the blood. Finally, the 

 liver helps to destroy some of the worn-out cells of the 

 blood (the red corpuscles), and the waste materials thus 

 formed are passed off into the intestine as a part of the bile. 



Functions of the Bile. We have already noted the fact 

 that the bile duct and the duct from the pancreas unite 

 before reaching the intestine. Hence, the bile and pancreatic 

 juice are mixed when they are poured upon the food. It is 

 difficult, for this reason, to distinguish with certainty between 

 the functions of the two juices. Some physiologists main- 

 tain that the bile forms an emulsion with fats after the 

 same manner as the pancreatic juice; others declare that it 

 has no digestive action whatever, and is merely a waste ma- 

 terial passed off by the liver into the intestine. 



We know that the bile is alkaline; it is therefore probable 

 that at least it assists the pancreatic juice in digesting fats. 

 It is certainly true that the absorption of fats through the cells 

 of the villi into the lacteals is promoted by the presence of 

 bile, for in cases of jaundice a considerable percentage of the 

 fats we eat is discharged from the large intestine with the 

 waste material. Again, the alkaline bile causes the muscles 

 of the intestines to contract rhythmically, thus forcing the 

 food onward toward the large intestine. For this reason, the 

 best means of avoiding constipation is to secure the presence 

 of a sufficient quantity of bile in the intestine. Calomel 

 and similar drugs are often given in case of constipation, 

 because they stimulate the liver to greater activity. And, 

 finally, bile acts as an antiseptic to prevent the decay of the 

 refuse material as long as it remains within the intestines. 



