ystem or liver rather than
of the kidneys, yet, as the most prominent symptom is the sweet urine,
it may be treated here.

_Causes._--Its causes are varied, but resolve themselves largely into
disorder of the liver or disorder of the brain. One of the most
prominent functions of the liver is the formation of glycogen, a
principle allied to grape sugar, and passing into it by further
oxidation in the blood. This is a constant function of the liver, but in
health the resulting sugar is burned up in the circulation and does not
appear in the urine. On the contrary, when the supply of oxygen is
defective, as in certain diseases of the lungs, the whole of the sugar
does not undergo combustion and the excess is excreted by the kidneys.
Also in certain forms of enlarged liver the quantity of sugar produced
is more than can be disposed of in the natural way, and it appears in
the urine. A temporary sweetness of the urine often occurs after a
hearty meal on starchy feed, but this is due altogether to the
super-abundant supply of the sugar-forming feed, lasts for a few hours
only, and has no pathological significance. In many cases of fatal
glycosuria the liver is found to be enlarged, or at least congested, and
it is found that the disorder can be produced experimentally by agencies
which produce an increased circulation through the liver. Thus Bernard
produced glycosuria by pricking the oblong medulla at the base of the
brain close to the roots of the pneumogastric nerve, which happens to be
also the nerve center (vasomotor) which presides over the contractions
of the minute blood vessels. The pricking and irritation of this center
leads to congestion of the liver and the excessive production of sugar.
Irritation carried to this point through the pneumogastric nerve causes
saccharine urine, and, in keeping with this, disease of the pancreas has
been found in this malady. The complete removal of the pancreas,
however, determines glycosuria, the organ having in health an inhibitive
action on sugar production by the liver. The same result follows the
reflection of irritation from other sources, as from different ganglia
(corpora striata, optic thalami, pons, cerebellum, cerebrum) of the
brain. Similarly it is induced by interruption of the nervous control
along the vasomotor tracts, as in destruction of the upper or lower
cervical sympathetic ganglion, by cutting the nervous branch connecting
these two, in injury to the spinal mar