268 DIGESTIVE SYSTEM. 



of these vessels ; these cells thus form an organ quite distinct 

 from the much larger one constituted by the hepatic cells, 

 properly so called (Ch. Robin, "Du Microscope," 1871). 



The final results obtained by histology are not thus op- 

 posed to the physiological distinction made between a biliary 

 and a glycogenic gland. It appears, however, that the great 

 question of the physiology of the liver is not yet solved ; for 

 recent physiological and experimental researches seem to 

 show that the glycogenic function is by no means peculiar 

 to this organ, as was at first so firmly believed, but is a 

 property common to all the tissues, and only carried to a 

 slightly higher degree in the hepatic organ. These re- 

 searches are chiefly connected with the study of diabetes, 

 and, with regard to this disease, we shall see that it is 

 going too far to completely deny the glycogenic functions 

 of the liver (Yulpian, Cours de mai, 1872). 



Cl. Bernard first proved that animal as well as vegetable 

 organisms produce sugar. Magendie had, before this, dis- 

 covered sugar in the blood, but in the herbivorous animals 

 only ; Cl. Bernard proved that it also exists in the carnivora, 

 but that scarcely any signs of it are found in the portal vein, 

 while a comparatively large quantity is found in the hepatic 

 veins. He also showed that the presence of this sugar 

 cannot be accounted for by any such storing up of the 

 saccharine elements of the food received as occurs in the 

 case of certain poisons, but that sugar exists in the liver 

 quite independently of external supply. The sugar produced 

 in the liver he shows is similar to that found in the urine of 

 patients suffering from diabetes, and that this disease is only 

 a pathological exaggeration of the normal glycogenic func- 

 tion. This function of the liver begins in the foetus, appar- 

 ently only at the age of three or four months: before this 

 time, the placenta seems to perform a similar office, by means 

 of a layer of glycogenic cells, placed between the foetal and 

 maternal placenta (Cl. Bernard, 1847-1855). 



Cl. Bernard soon became convinced that the globular ele- 

 ments of the liver do not form sugar directly, but rather that 

 there is a substance which is capable of being transformed 

 into sugar, a glycogenous substance resembling starch, and 

 which is changed into glucose by means of the same agents 

 as starch. This glycogenous substance can only be changed 

 into sugar in the organism by the action of a ferment which 

 is produced in the liver, or brought into it by the blood. 

 Bernard became convinced of this by observing that the 



