OHAP. v.] NUTRITION. 425 



region of the cerebro-spinal centre which we already know as 

 the vaso-motor centre, or at least of a part of that region. The 

 path of the influence may be traced along the cervical spinal cord 

 (and not along the vagi, though the roots of these nerves lie so 

 close to the diabetic spot), as far down as (in rabbits) the level of 

 the third or fourth dorsal vertebra, or even a little lower, from 

 the spinal cord to the first thoracic ganglion, and from thence to 

 the liver by some channel or channels at present undetermined. 

 We cannot at present define clearly the nature of that influence. 

 We cannot say whether the temporary diabetes is a simple effect 

 of a dilation of the hepatic arteries which accompanies the diabetic 

 puncture or of some direct action of the nerves on the metabolic 

 activity of the hepatic protoplasm, though the latter view seems 

 the more probable one. 



Artificial diabetes is also a prominent symptom of urari poison- 

 ing. This is not due to the artificial respiration, which is had 

 recourse to in order to keep the urarized animals alive ; because, 

 though disturbance of the respiratory functions sufficient to inter- 

 fere with the hepatic circulation may produce sugar in the urine, 

 artificial respiration may with care be carried on without any 

 sugar making its appearance. Moreover, urari causes diabetes in 

 frogs, although in these animals respiration can be satisfactorily 

 carried on without any pulmonary respiratory movements. The 

 exact way in which this form of diabetes is brought about has not 

 yet been clearly made out. 



A very similar diabetes is seen in carbonic oxide poisoning; 

 and is one of the results of a sufficient dose of morphia or of amyl 

 nitrate. 



There can be no doubt that in diabetes, arising from whatever 

 cause, the sugar appears in the urine because the blood contains 

 more sugar than usual. The system can only dispose (either by 

 oxidation, or as seems more probable in other ways) of a certain 

 quantity of sugar in a certain time. Sugar injected into the 

 jugular vein reappears in the urine, whenever the injection becomes 

 so rapid that the percentage of sugar in the blood reaches a certain 

 (low) limit. Sugar in the urine means an excess of sugar in the 

 blood. How in natural diabetes that excess arises, has not at 

 present been clearly made out. It may be that some forms of 

 diabetes resemble the artificial diabetes just described as resulting 

 from puncture of the medulla, and arise from a too rapid con- 

 version of the hepatic glycogen or from carbohydrate material 

 failing to be stored up as glycogen. All forms of diabetes how- 

 ever cannot be satisfactorily explained in this way; and it has 

 been suggested, though adequate proof has not yet been supplied, 

 that the sugar of diabetes is of a peculiar nature and accumulates 

 in the blood because it is unable to undergo those changes, what- 

 ever they be, which befall the normal sugar of the blood. We 

 must not pursue the subject any further; but there is much to 



