138 Oxygen in the Venous Blood. I 
the oxygen unsaturation of the venous blood, since it represents 
that portion of the hemoglobin which does not have its oxygen- 
binding values saturated. The term unsaturation is used in a 
sense analogous to that in which it is used in organic chemistry, 
defined by Webster as “‘falling short of saturation, not combined 
to the greatest possible extent.’’? 
Thirty-eight determinations on twelve different normal in- 
dividuals have been done. In Table I are given twenty determina- 
tions on one person, and in Table II eighteen determinations on 
eleven different people. Care has been taken to draw the blood 
from a person resting as completely as possible, because we know 
that an increase in the metabolism necessarily is followed by an 
increased oxygen consumption. Before the drawing of the blood 
the subjects rested on a couch for some time, in some experiments 
10 minutes, in others half an hour. In some instances the blood 
was taken in the morning, before getting up. It does not seem 
to make any difference whether the resting period is 10 minutes 
or 30. The oxygen content of the blood taken in the morning 
had a tendency to be low, particularly when the person had been 
awake only a few seconds. The average figure for the oxygen 
content in the twenty determinations on No. 1 is 13.7 volume per 
cent, with a maximum of 16.84 volume per cent and a minimum 
of 9.55. The average figure for the eighteen determinations on 
the other cases is 13.6 volume per cent, with a maximum of 17.98 
and a minimum of 10.36 volume per cent. 
The total oxygen-combining power (the hemoglobin) has varied 
from 21.44 (hemoglobin 116 per cent) to 17.50 (hemoglobin 
94.5 per cent). This must, of course, influence the amount of 
oxygen in the venous blood. In the determination in No. 27, 
for instance, the amount of oxygen in the venous blood is greater 
than the total capacity of the hemoglobin in No. 36. Such meas- 
ures illustrate the necessity of taking as a measure of oxygen 
7 The term oxygen consumption has been applied to the figure for which 
we prefer the more exact term unsaturation. The use of consumption in 
this connection implies that all the venous oxygen which the venous blood 
requires in order to be saturated is lacking for the reason that it has been 
consumed by the tissues. This assumption would be correct if one could 
always be certain that the arterial hemoglobin is 100 per cent saturated 
with oxygen. Since one cannot be certain of this, it seems preferable to 
use the term unsaturation, which is free from the above assumption. 
