514 THE LIVER [cir. xxxm. 



actually produced in the blood. But all recent work shows that the 

 liver is the only place where production of bile occurs, and that in all 

 cases of so-called non-obstructive jaundice, the bile is absorbed from 

 the liver. There may be obstruction present in the smaller ducts, or 

 the functions of the liver may be so upset that the bile passes into 

 the lymph even when there is no obstruction. 



The Glycogenic Function of the Liver. 



The important fact that the liver normally forms sugar, or a 

 substance readily convertible into it, was discovered by Claude 

 Bernard in the following way: he fed a dog for seven days with food 

 containing a large quantity of sugar and starch; and, as might be 

 expected, found sugar in both the portal and hepatic blood. But 

 when this dog was fed with meat only, to his surprise, sugar was still 

 found in the blood of the hepatic veins. Eepeated experiments gave 

 invariably the same result ; no sugar was found, under a meat diet, 

 in the portal vein, if care were taken, by applying a ligature on it at 

 the transverse fissure, to prevent reflux of blood from the hepatic 

 venous system. Bernard found sugar also in the substance of the 

 liver. It thus seemed certain that the liver formed sugar, even when, 

 from the absence of saccharine and amyloid matters in the food, 

 none could have been brought directly to it from the stomach or 

 intestines. 



Bernard found, subsequently, that a liver, removed from the 

 body, and from which all sugar had been completely washed away by 

 injecting a stream of water through its blood-vessels, contained sugar 

 in abundance after the lapse of a few hours. This post-mortem pro- 

 duction of sugar was a fact which could only be explained on the 

 supposition that the liver contained a substance readily convertible 

 into sugar; and this theory was proved to be correct by the dis- 

 covery of a substance in the liver allied to starch, and now termed 

 glycogen or animal starch. 



We are thus led to the conclusion that glycogen is formed first 

 and stored in the liver cells, and that the sugar, when present, is the 

 result of its transformation. 



Source of Glycogen. Although the greatest amount of glycogen 

 is produced by the liver upon a diet of starch or sugar, a certain 

 quantity is produced upon a proteid diet. It must, then, be produced 

 by protoplasmic activity within the cells. The glycogen when stored 

 in the liver cells may readily be demonstrated in sections of liver 

 containing it by its reaction (red or port-wine colour) with iodine, and 

 moreover, when the hardened sections are soaked in water in order to 

 dissolve out the glycogen, the protoplasm of the cell is so vacuolated 

 as to appear little more than a framework. In the liver of a hiber- 



