FUNCTIONS OF THE LIVER. 271 



The sugar thus formed is poured into the blood, and, being 

 drawn on by the current of the circulation, soon disappears, 

 being either consumed in the lungs or destroyed by oxida- 

 tion, or by some other means in some part of the economy. 

 In this way little or no sugar is left in the blood, but when- 

 ever the quantity formed is too considerable, and is not com- 

 pletely destroyed, glycsemia ensues; and if the quantity 

 exceed three per cent of the solid residuum of the blood, or 

 if it is more than from two to three grammes to every kilo- 

 gramme of the animal's weight (Kiihne), the sugar is excreted 

 by the kidneys, and the glycaemia appears as glycosuria or 

 diabetes. 



This increase in the production of sugar, and the conse- 

 quences which follow, may be artificially produced by various 

 methods, which confirm the theory of hepatic glycogeny, by 

 more or less directly affecting the liver. 



Thus the injection of irritants into the portal vein (ether, 

 Harley) brings on glycosuria. This is, no doubt, the effect 

 of certain more or less poisonous substances when absorbed 

 by different organs, such as chloroform, woorara (?), putrid 

 matters, etc. : the latter, no doubt, help to increase the fer- 

 ment necessary to change the glycogen into sugar. All those 

 conditions, in fact, which are favorable for fermentations 

 serve to produce and increase diabetes, while all those which 

 hinder fermentation tend to diminish or even to check it 



of the liver is derived from a substance formed in the liver, which 

 substance he examines (1857), finding in it features resembling 

 those of vegetable starch. In 1859, while seeking for the origin 

 of this glycoyenous substance, he found it to exist in the placental 

 organs of the mammalia, in the vitelline membrane of birds, and 

 in the inferior animals when in the larval or chrysalid state. He 

 then shows that the glycogenic cells are first found on the inner 

 surface of the amnion of the mammalia, where, about the middle 

 of gestation, they form well developed papillae, disappearing after- 

 wards when the glycogenic function becomes established in the liver. 

 In birds the glycogenic cells are first placed along the passage of 

 the omphalo-mesenteric veins, and then at the extremities of the 

 vitelline veins, which form actual glycogenic villi floating in the 

 substance of the yolk. The glycogenic substance is thus at first 

 diffused throughout the organs of the embryo in a transitory form, 

 and only finally appears in the liver, where it remains. On the 

 other hand, animal glycogeny really constitutes a chemical evolu- 

 tion of the starchy elements, an evolution which resembles, or, 

 rather, is identical with that exhibited by the starch found in vege- 

 table organisms (Cl. Bernard, Cours de 1872). 



