THE METABOLISM OF THE BODY. , 435 
used up in the blood, it is not oxidized there; but by what 
tissues it is used or how it is made available in the economy is 
a subject on which we are profoundly ignorant. The presence 
of so much glycogen in the partially developed tissues of the 
foetus points to its importance, and suggests its being a crude 
material which is laid up to be further elaborated, as in vege- 
tables, by the growing protoplasm. 
Glycogen being so generally present in muscle, its diminu- 
tion running parallel, to some extent at least, with the func- 
tional activity of the tissue, it is clear that there is some im- 
portant purpose served; but here again we inquire, What ? 
Pathological.—If a point in the medulla oblongata of a rabbit, 
corresponding nearly or completely with the vaso-motor center, 
be punctured, the urine will in a few hours be found aug- 
mented in quantity and containing sugar. 
It is further found that the quantity of the latter bears 
some relation to the diet of the animal, one well fed on carbo- 
hydrates having more sugar in the urine than a fasting animal. ° 
From these facts it has been concluded that the nervous system 
has lost a customary normal influence over the glycogenic 
function, either directly through the action of the nerves on 
the liver-cells or through the loss of tone arising from injury 
to the vaso-motor center. Poisoning by carbonic oxide and the 
administration of certain drugs also causes sugar to appear in 
the urine. 
The symptoms resulting from puncture of the medulla, etc., 
have been spoken of as “ artificial diabetes ”—a very objection- 
able term for which artificial glycosuria should be substituted. 
There is a grave and often fatal disease known as diabetes 
mellitus, one of the symptoms of which is the appearance often 
of enormous quantities of grape-sugar in the urine. But all 
attempts to fathom the depths of obscurity which surround this 
malady have been in vain. It would seem that attention has 
been directed too exclusively to the liver. Cases of the disease 
occur in which at the post-mortem examination the liver may 
be perfectly normal in appearance, or either hyperemic or 
anemic. 
It seems to us that it is likely that the disease will be shown 
to be of diverse origins, or certainly not referable to one organ 
solely in most cases. The conclusion that the nervous system 
is greatly concerned, both in directing the glycogenic functions 
of the liver and in the disease in question, seems to be un- 
doubted ; vaso-motor effects, when present, being probably of 
