516 THE LITER [CH. XXXIII. 



Pavy further denies that the post-mortem formation of sugar from 

 glycogen that occurs in an excised liver is a true picture of what 

 occurs during life, but is due to a ferment which is only formed after 

 death. During life, he regards the glycogen as a source of other 

 substances, like fat and proteid. It is certainly a fact that increase 

 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 proteids, he has shown that many proteids 

 contain a carbohydrate radicle. 



The whole question is under keen discussion at present. We 

 may state, however, that the prevalent opinion is that the liver- 

 cells may be able to convert part of the store of glycogen into fat, 

 but that 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 hepatic metabolism, the 

 glycogenic function is upset, and excess of sugar passes into the 

 blood, leaving the body in the urine (glycosuria). This may be due 

 to an increased formation of sugar from glycogen, or to a diminished 

 formation of glycogen from the sugar of the portal blood, according 

 as either Bernard's or Pavy's view of the liver function is adopted. 

 In many cases the diabetic condition may be removed by a close 

 attention to diet; starchy and saccharine food must be rigidly 

 abstained from. 



In other cases, which are much more serious, diet makes little or 

 no difference. Under these circumstances the sugar must come from 

 the metabolism of the proteid constituents of protoplasm. 



The disease diabetes is not a single one ; the term includes many 

 pathological conditions, which all possess in common the symptom of 

 excess of sugar in the blood and urine. 



A diabetic condition may be produced in animals artificially in 

 several ways : 



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

 that injury to the floor of the fourth ventricle in the region of the 

 vaso-motor centre leads to glycosuria. The injury produces a dis- 

 turbance of the vaso-motor mechanism, but diabetes cannot be 

 regarded as purely vaso-motor in origin. This condition is of 

 interest, because brain disease in man, especially in the region 

 of the bulb, is frequently associated with glycosuria. 



(2) By extirpation of the pancreas. (See also p. 500). It is 

 probable that in diabetes, the oxidative powers of the body-cells are 

 lessened. Nevertheless, other diseases in which diminished oxidation 

 occurs are not necessarily accompanied with glycosuria. The diffi- 

 culty in diabetes probably lies in an impairment of the capacity of 

 the cells of the body to prepare the sugar for oxidation. In this 



