104 L. B. WINTER AND W. SMITH.
was treated as has been described above. The final filtrate when read in
a one decimetre polarimeter tube usually gave a value considerably
below that obtained by the copper reduction method. The copper reduc-
tion value was calculated as glucose. Calculating also the polarimeter
reading as glucose the difference between the two results was very
The work of Hewitt and Pryde(s) suggested that an unstable form
of glucose might be present; the tubes were therefore read for at least
three days after the completion of the experiment. The readings in each
case gradually approached, and usually reached at the end of this time,
a rotation corresponding to the c, , equilibrium form of glucose. The
copper reducing value was unaltered at the end of this time. As men-
tioned above, the speed at which the concentration of the aqueous
filtrate is carried out is of the greatest importance. If faulty water-
pressure delays the concentration, or the temperature is allowed to rise
unduly, the polarimetric is very close to, or even above, the copper value.
It was found that rapid concentration was most readily effected by
emiploying large distilling flasks of two litre capacity. The distillation
wvas begun with only about one half of the filtrate, the remainder being
added at intervals by means of a funnel connecting with the capillary.
The effect of this is to enable the distillation to proceed smoothly and
continuously while the fluid is being added, and at the same time avoids
the necessity of allowing air to enter the flasks in order to stir up the
To test whether appreciable alteration in the state of the sugar took
place at room temperature when in contact with the precipitated proteins,
two samples of the same blood were taken: one was precipitated, filtered
immediately, and proceeded with as usual; the other was precipitated,
allowed to stand for six hours, and then filtered and treated as usual.
The readings of the final products were both identical as regards their
copper reducing and polarimetric values.
Some experiments were carried out to determine whether a ferment
or ferments are present in blood which will convert added glucose to
another form of sugar. The sugar was added before and after precipitation
of the proteins and allowed to stand at room temperature, 20° C., for
one hour. The amount of glycolysis being inappreciable under these
conditions, almost identical results were obtained from the two samples,
indicating that no such ferment can be present, or at any rate, that it is
unable to work under the conditions of our experiments. Hewitt and
Pryde's experiments(s) suggested that if any change were to take place