A principal function of the blood is that of respiration, giving oxygen to the tissues and receiving carbon dioxide. The difference in the gaseous content of arterial and venous blood is a measure of the metabolic activity of the tissues or of the speed of the blood flow through them, or of both. To what extent do the various portions of the body vary in their utilization of oxygen? Is the blood taken from a superficial vein of the arm essentially the same in its gaseous composition as blood taken from other accessible veins ?
The only observations bearing on this subject that we have seen are those made during certain experiments on animals by Uyeno and Dor.1 They gave values for the oxygen saturation of the blood (as determined by the Barcroft differential apparatus) in various veins in six experiments. These values varied widely.
In order to answer the