538 THE LIVER [en. xxxv. 



of carbohydrate food leads to the formation of fat in the body and in 

 the liver-cells. In support of the theory that glycogen may also con- 

 tribute to the formation of proteins, he has shown that many proteins 

 contain a carbohydrate radical. 



The prevalent opinion is that the liver-cells may be able to con- 

 vert part of the store of glycogen into fat ; part also of the sugar 

 formed from glycogen may unite with protein to form a gluco- 

 protein; but most of the glycogen leaves the liver as sugar 

 (dextrose), so justifying the name (literally, mother-substance of 

 sugar) given to it by Bernard. 



Diabetes. In certain disorders of metabolism, excess of sugar 

 occurs in the blood, and leaves the body by the urine (glycosurid). 

 Under normal circumstances, the transformation of the hepatic 

 glycogen into sugar is a sufficiently slow process to keep the sugar 

 in the blood at such a low percentage that glycosuria does not occur. 

 Glycosuria takes place when the transformation of glycogen into 

 sugar is excessive, as in puncture diabetes, described below. 



"Alimentary glycosuria" is usually a temporary condition, in 

 which either the diet contains too much carbohydrate for the liver to 

 store as glycogen, or else the liver is comparatively inactive and 

 incapable of dealing with the usual carbohydrate supply. This state 

 of things may be remedied by reducing the amount of carbohydrate 

 ingested, or by improving the condition of the liver. The normal 

 " assimilation limit " for dextrose in man given in one dose by the 

 mouth is about 200 grammes. 



We must, however, remember that sugar is not poured into the 

 blood to accumulate there, but is removed by the muscular and other 

 tissues which the blood traverses, and is there burnt to serve as a 

 source of energy ; if the tissues are unable to utilise the sugar in 

 this way, it accumulates in the blood and overflows into the urine ; 

 this is the usual condition in the disease called diabetes mellitus in 

 man; and a similar condition may be produced in animals by 

 removal of the pancreas. Many cases of diabetes mellitus in man 

 are due to disease of the pancreas. In many cases the diabetic 

 condition may be removed by rigid abstention from starchy and 

 saccharine food. In other cases diet makes little or no difference; 

 in this condition the sugar must come from the metabolism of the 

 protein constituents of protoplasm ; 40 per cent, or more of the kata- 

 bolised protein may leave the body as sugar, certain of its cleavage 

 products (for instance, alanine, see p. 615) acting as intermediate 

 substances in sugar formation. This serious condition is analogous to 

 what can be produced artificially by the poison known as phloridzin, 

 and is possibly produced in man by some poison acting in a similar way. 



The principal ways in which diabetes may be produced are : 



(1) By diabetic puncture. Claude Bernard was the first to show 



