DIA BETES. 259 



on a carbohydrate diet is a well-known fact, and one of the re- 

 strictions placed upon obese individuals who are endeavoring; to 

 reduce their fat is to abstain from sugar as much as possible. The 

 glycogen of the muscles may also serve for the purpose of fat 

 formation. That glycogen serves also as a source of energy there 

 is no doubt. 



It may seem to the student a strange fact that what appears so 

 simple a matter to determine as this which is in dispute between 

 the adherents of the two theories referred to cannot be definitely 

 settled ; but it is to be borne in mind that the blood is a very 

 complex fluid, and the methods for detecting with certainty the 

 amount of sugar in the blood are not sufficiently exact to warrant 

 a positive statement, for in this fluid there are other reducing 

 substances than sugar. Then, too, it must be remembered that 

 the entire blood of the body passes through the liver every two 

 minutes, so that while the total amount of sugar passed out from 

 that organ in twenty-four hours might be considerable, yet the 

 difference in amount found at any given moment in the blood of 

 the hepatic vein, over and above that found in other parts of the 

 circulation, would be so small as not to be within the possibility 

 of determination. In view of the conflicting evidence we must, 

 therefore, acknowledge that the question is still an open one, with 

 the weight of evidence at the present time in favor of the theory 

 of Bernard. 



Diabetes. This is " an affection characterized by an immoder- 

 ate and morbid flow of urine." When there is no sugar in such 

 urine the condition is called diabetes insipidus ; but when the 

 urine contains an abnormal amount of sugar, diabetes mellitus, or 

 simply diabetes. The term glycosuria refers to the excessive 

 amount of sugar in the urine, and this condition may exist, tem- 

 porarily, in other affections than diabetes. The form in which the 

 sugar exists is principally that of dextrose, though there is doubt- 

 less some maltose also present. The source of this sugar may be 

 from glycogen or from proteids. If from the former, it may be 

 caused by excessive conversion of glycogen into dextrose (Ber- 

 nard), or from a failure on the part of the liver to convert into 

 glycogen as much of the absorbed sugar as occurs normally (Pavy). 

 Whichever view is taken, the treatment consists, among other 

 things, in depriving the patient of all foods which make sugar. 

 In some cases, however, even after this is done, the glycosuria 

 continues, and the only possible explanation is that the sugar is 

 produced from proteids. 



Artificial Diabetes. The condition of glycosuria may be arti- 

 ficially produced : 



(1) Puncture-diabetes. Puncture in the floor of the fourth 

 ventricle of the brain, the region in which is situated the vaso- 

 motor center, will cause glycosuria. This center is stimulated 

 by the puncture, the arterioles of the liver are constricted^, thus 



