SUGAR OF BLOOD. 103
a sample of pure glucose (for this we are indebted to Dr C. G. L. Wolf).
The degree of accuracy obtained may be seen from the following figures.
Glucose weight taken .2435 gm. made up to 100 c.c. with water.
Copper reduction value *23 %
Polarimeter...... *242 ,,
The polarimeter used is a three field instrument made by Hilger
of London, the illumination being the mercury green line. This has the
advantage of giving a higher specific rotation than that obtained from
the sodium light. The light also is steady and can easily be varied in
intensity by the resistances with which it is conneced. By means of the
instrument used readings to 01 degree can be obtained. The mean of a
series of readings by each of us was taken whenever possible. As a
rule complete agreement was obtained; it was noticeable though that
when one of us had been bled this agreement no longer held; in these
cases the reading from the other was accepted. It had been previously
noticed that a comfortable position and normal mental state are
necessary for reading colorimeters and similar instruments.
The amount of sugar extracted is approximately ½ to - of that
indicated as being present by the micro estimation. There is no possibility
of more than one sugar being present and of one being preferentially
extracted by the solution of alcohol employed, as no trace of sugar was
found to be extracted by water after the alcohol treatment had been
completed. From the final filtrate in some of our experiments an osazone
was prepared. This was recrystallised. Microscopic examination showed
only glucosazone to be present; melting point determination gave 205° C.,
which was sharp and well defined. This figure corresponds to the accepted
value of the melting point of glucosazone.
The figures obtained by Bang's old method (this was used by us for
the quantitative estimation of the blood sugar content) give only an
approximation to the actual content in the whole quantity of blood
drawn owing to the sample being obtained at one period only of the
operation. This should be noted in connection with the nervous factor
which is apparent in one of the cases discussed below.
Experirnents with animal blood.
A series of experiments was carried out using the blood of different
animals, ox, sheep, cat and rabbit. That from the ox and sheep was
obtained from the slaughter house; that of the other animals, from those
killed for the purpose in the laboratory without anæesthetics. 25 to
100 c.c. were usually employed, depending upon the animal. This blood