DIABETES MELLITUS. 833 



yet thrown light upon the mystery. We know that the presence of 

 sugar in the urine, whence diabetes mellitus derives its name, does not 

 depend upon functional abnormity of the kidneys ; that the sugar is 

 not formed in them, and that it is excreted from the blood ; but we 

 are altogether ignorant wherein the constitutional anomaly consists, in 

 consequence of which a diabetic patient's blood contains* sugar, and a 

 healthy person's none. As the various hypotheses offered to account 

 for diabetes are of little practical value, we shall mention a few merely 

 of those most generally entertained. 



In the first place, diabetes has been ascribed to an insufficient de- 

 gree of transformation of the sugar in the blood. Indeed, if the sugar 

 into which the amylaceous substances that have been eaten are con- 

 verted, and that which is formed in the liver, were to circulate in the 

 blood without undergoing further alteration, and if this substance did 

 not disappear again from the blood during its passage through the 

 lungs, it would necessarily form one of the normal constituents of the 

 urine ; hence it cannot be denied that the. pathological presence of 

 sugar in the urine may possibly depend in some cases upon a failure 

 of the conditions under which the normal transformation of the sugar 

 takes place. However, as long as we are ignorant as to what these 

 conditions are, we obtain but little aid from the hypothesis that their 

 absence is the cause of diabetes. The assertion, that the non-assimila- 

 tion of sugar in the circulation of diabetic persons is due to a want of 

 alkalies in the blood, has been disproved. The theory of the existence 

 in the blood of healthy persons of a certain unknown ferment, which 

 induces the assimilation of sugar, but which is absent in the blood of 

 diabetic persons, is untenable. 



Others have sought to trace the origin of diabetes to an abnormal- 

 ly accelerated conversion of amylaceous matter into sugar, this being 

 due to a diseased condition of the digestive juices. To this theory 

 there are still greater objections than to the preceding ones. It seems 

 that even in healthy persons the amylaceous ingesta are all changed 

 into sugar (Trommer has proved this to be the case even in geese 

 that have been "crammed"), and yet we know that healthy urine 

 never contains sugar even after the ingestion into the system of very- 

 large quantities of amylaceous matter, or of pure sugar. But the re- 

 sult of the treatment based upon these hypotheses has afforded the 

 best evidence of their unsoundness. Were the source of diabetes an 

 over-active and immoderate conversion of amylum into sugar, the dis- 

 ease should cease upon the stoppage of the supply of amylum. Ex- 

 perience, however, teaches us the contrary ; as, even where for weeks 

 and months the food of the patient has been exclusively animal food, 

 the sugar rarely disappears from the urine. Finally, since Claudt 



