SUGAR OF BLOOD. 107
at the beginning of each curve. This shows that the sugar which recently
entered from the intestine had been converted into normal blood sugar.
COPPER VALUE
II
DAYS
I I I I
Fig. 2. Increase of polarimeter reading on successive days. L. B. W. I. Normal. II. After
100 grams of glucose. III. After 150 grams of fructose. (The curves are scaled to a common
copper value.)
In view of the facts mentioned above, it became of interest to see
whether the blood of patients suffering from diabetes mellitus differed
from that of normal persons. The cases investigated of subjects suffering
from diabetes have all been of the severe type. As a consequence it has
only been possible to obtain a comparatively small quantity of blood
from each. It is important to note that owing to the high sugar content
a much smaller quantity of blood is required with a consequent accelera-
tion of the manipulation. If the blood sugar was even approximately
normal in quality it should be very evident, since there would be less
time elapsing between the precipitation and the final product. In three
cases the polarimeter reading was slightly above the copper reducing
value. Any considerable amount of ,-oxybutyric acid present in the
final filtrate would tend to throw the rotation in a laevo direction, as the
l-form is the only one present in these cases. The curves reached the
copper value on the second or third days. In one case the polarimeter
reading was considerably above that of the copper reducing value; the
possible meaning of this is discussed later.
It is probable then, that in severe cases at any rate the normal
blood sugar is present only in very small amounts and it is possible that
the failure to utilise sugar is due to the lack of some ferment, which has