In the first paper1 a method for the accurate evaluation of brilliant vital red in the plasma was described. If the measurement of the dye concentration is to serve as an index of the total plasma volume, the mixing of the injected dye with the plasma must be complete throughout the circulation before there is any appreciable loss of dye. Two problems, then, would naturally follow: (1) to determine the time required for complete mixing of dye and plasma and (2) to find the rate of loss from the blood stream. These problems can be studied by determining the dye concentration in a series of samples of plasma taken at frequent measured intervals after the injection of the dye. The present communication deals with this study.
Measured volumes of dye of known concentration were injected into the median basilic vein of one arm, and 10 cc. samples were periodically