DESPITE differences in opinion regarding the mechanism leading to shock, it is now agreed that this condition should not be treated with solutions of crystalloids. The best prophylactic and therapeutic agents are considered to be blood and plasma. However, these have several disadvantages. The provision of large quantities is difficult and expensive, their administration is attended by inevitable delay and by the risk of untoward reaction and of the transmission of virus infection. Early experimental and clinical experience showed that in the treatment of shock the maintenance of an adequate volume of blood in circulation and of oxygen transport at a sufficient level was of primary importance. The amount of blood in circulation is determined to a large extent by the nature of the colloids in plasma and especially by the purely physical properties of these colloids. In this respect, their biologic properties are of minor significance.1 As soon as this fact was learned, attempts