CHAP. XXV.] USE OF THE BILE. 26 1 



in them to a great extent, so as to occasion enormous enlargement 

 of that organ. And in some fishes the liver is naturally, at certain 

 periods,, loaded with it. It is a point of great interest to determine, 

 whether this fat simply accumulates in the hepatic cells, as it 

 does in other tissues, or whether it may not be regarded as a part 

 of the secretion of the liver ; in other words, can it be a part of 

 the office of the liver to recombine certain elements of the absorbed 

 food, and to form fat, which, on being discharged into the intestinal 

 canal, is absorbed by the villi?* 



In connexion with this subject we may refer here to a remark- 

 able fact lately brought to light by Bernard, which denotes that 

 chemical changes take place in the blood while it is passing 

 through the liver, whereby a material is generated in it which had 

 not been introduced in the food. 



Bernard has found that sugar is developed in the hepatic capil- 

 laries, even when it is not present in the intestines, or in any of the 

 tributary veins of the vena portae. A dog, which had been fed 

 some hours previously on substances destitute of starch and sugar, 

 was quickly killed, the abdominal cavity was immediately opened, 

 and ligatures were placed on the mesenteric, splenic, and pancreatic 

 veins, and on the trunk of the vena portae. Blood collected from 

 each of these sources, on the distal side of the ligature, proved on 

 examination destitute of sugar in all, except the vena portae, in 

 which it was readily detected. Sugar was also found in the tissue 

 of the liver itself. If, then, sugar exists in the vena portae, but not 

 in its tributary veins, how does it get to the former ? As it exists 

 in the tissue of the liver, it is evident that it passes to the vena 

 portae by the reflux which, in the absence of valves in the portal 

 system, may take place after death. Hence it is reasonable to 

 infer that sugar is formed in the hepatic capillaries, and carried 

 by the hepatic veins to the right side of the heart, in the blood of 

 which Bernard states that sugar is constantly present, whatever 

 food the animal may have been fed on, and even after a long 

 fast. 



The evidence of the presence of sugar in the liver is obtained in 

 the following manner : A portion of the liver is beaten in a mortar, 

 and then boiled in a small quantity of water, and filtered. The 

 filtered liquid possesses all the properties of a saccharine fluid ; 

 it becomes darker on being boiled with liquor potassae, and the 



* It is true that the fatty matter of the bile is not free ; but it may be sup- 

 posed to form its combinations after it has been discharged from the hepatic 

 cells, and while it is passing through the ducts of the liver. 



