The problem of preserving blood is greatly simplified when it is reduced to the preservation of its individual components. It has been estimated that the average adult body contains about 5 liters of blood, of which 2.75 liters is plasma, 2.22 liters is erythrocytes, 0.02 liter is platelets, and 0.01 liter is leukocytes.1 The blood fractionator developed under the direction of the late Dr. E. J. Cohn at Harvard University is an ingenious device which provides a continuous closed mechanical system for taking blood from a vein, separating it into the elements named, and packaging the fractions in sterile plastic containers. The apparatus is housed in a portable cabinet.
In order to prevent coagulation, calcium must be removed from the blood without delay. This is accomplished by passage of the blood through an exchange resin which gives up sodium and takes up calcium without damaging the cells. The resin