C. Lundsgaard 143 
consumption the oxygen unsaturation rather than the oxygen 
content of the venous blood. The average value of the oxygen 
unsaturation for Case 1 is 5.5 volume per cent, the minimum 
being 2.70, the maximum 8.95. The average for the eighteen 
determinations on Cases 2 to 12 is 6.0 volume per cent, with a 
minimum of 3.00, a maximum of 8.83 (Table IV). 
The determinations are too few to.allow an interpretation of the 
different causes of the variations.’ Series of determinations on 
different individuals under different conditions might throw 
light upon that problem. There is generally a decrease in the 
oxygen unsaturation with increasing pulse rate, but it is by no 
means invariable. It is worth mentioning that a value for the 
oxygen unsaturation of more than 8 volume per cent is found in 
only four instances, in all of which the blood was drawn in the 
morning, a few seconds after the subject awoke. In other words, 
the highest degree of unsaturation is found under circumstances 
where the metabolism is lowest, when the individual usually 
has his lowest pulse rate, and when all exciting impressions have 
been excluded for a considerable time. 
In some instances it has been impossible to do the blood analysis 
immediately after a bleeding. In order to find out how long, and 
under what conditions the blood samples can be stored, experi- 
ments have been done as shown in Table III. 
The figures show that the blood can be kept in an ice box at a 
low temperature (6°C.) for a considerable length of time (at least 
24 hours) before any appreciable changes take place. After a 
certain time the blood will absorb oxygen through the oil and the 
values will increase. [The opposite happens when the blood is 
kept in the laboratory. We cannot expect it to keep constant 
more than 2 hours. After that interval the oxygen content 
diminished rapidly, probably on account of bacterial action. 
8 A series of papers in which the technique described in this paper is 
applied to the clinical study of patients with heart disease will be published 
in The Journal of Experimental Medicine. 
