shown that the glycogenic power of the liver
of a diahetic dog could be restored by the
administration of insulin. In the first experi-
ment conducted with this end in view, the liver
of a diabetic dog afteP two days' treatment
with insulin was found to contain 25.6%5 of
glycogen. There was thus afforded definite
proof of the restoration under the influence of
insulin, of a function which was definitely
knoTwn to be lacking in the diabetic state.
The next step forward was the observation
that ketosis could be completely abolished in
diabetic animals by the use of insulin. This
suggested the re-establishment in the tissues
of a ketogenic-antiketogenic ratio, compatible
with complete oxidation of fatty acid. Iu
other words, it pointed to the restoration of
the power of the tissues to burn sugar and
thereby to burn completely fatty acids. Defin-
ite proof of a direct nature, however, was at
once obtained on this point. As more oxygen
is rcquired to burn a unit quantity of fat than
is required to burn a unit quantity of glucose.
C02 produced
we have in the ratio between C2 produced
02 used
an index of the relative amounts of fat and
sugar which are being consumed in the body
at any one time. This ratio is readily ascer-
tained by the comparatively simple process of
making an analysis of the expired air. The ratio
betweenCO0 produced is known as the respir-
02 used
atory quotient. A low respiratory quotient
indicates that little or no carbohydrate is being
oxidized whereas a high respiratory quotient
indicates the combustion of a variable amount
of carbohydrate. The respiratory quotient in
the diabetic state is invariably low, and the
injection of glucose has little or no effect upon
it. It was found, however, that either with or
without the injection of glucose the respiratory
quctient was raised very definitely following
the administration of insulin to the diabetic
12