142 PHYSIOLOGICAL CHEMISTRY. 



that the two above-mentioned opinions stand to-day in opposition 

 to each other. The existence of a vital formation of sugar from 

 the glycogen of the liver is denied by certain investigators, but ad- 

 mitted by others. Those who admit this formation claim that it is 

 produced by the action of an enzyme which is formed in the blood, 

 especially on the destruction of the red blood-corpuscles (TIEGEL). 

 Other investigators, such as FOESTEE, EVES, DASTEE and others, 

 deny the action of an enzyme, and are of the opinion that the for- 

 mation of sugar is produced by a vital action of the protoplasm of 

 the living cell. 



SEEGEIT claims that the sugar formation in the liver occurs on a 

 very large scale under physiological conditions, and that the blood 

 of the hepatic vein is considerably richer in sugar than the blood 

 of the portal vein. He also claims that the sugar is not formed 

 from the glycogen, but from the peptones and fat. The observa- 

 tions which form the basis of this theory have not been confirmed 

 by other investigators (CHITTENDEJT and LAMBEET). 



The question as to a physiological formation of sugar in the 

 liver is disputable and not settled. There is no doubt that in cer- 

 tain lesions of the nervous system, by poisoning, etc., an abundant 

 formation of sugar may appear, which, at least in certain cases, is 

 derived from the glycogen of the liver, and several investigators 

 consider with CL. BEE^AED this sugar formation as well as the 

 elimination sugar in diabetes mellitus, as an increase in the normal 

 formation of sugar from the glycogen. 



A discussion of the different views in regard to glycosuria 

 and diabetes mellitus is beyond the plan and scope of this 

 book. The appearance of glucose in the urine is a symptom 

 which under different conditions may have essentially different 

 causes. Under all circumstances it is necessary to carefully differ- 

 entiate between those diseased conditions on the one side which 

 are grouped under the name diabetes mellitus and the experi- 

 mental production of glycosuria on the other side. In diabetes, at 

 least in most cases, we are more probably dealing with a decreased 

 burning-up of sugar in the organism than an increased production 

 of sugar from the glycogen of the liver, or a disturbed storing-up 

 of glycogen in this organ. On the contrary, in experimental gly- 

 cosuria in certain cases we have undoubtedly a formation of sugar 



