SINCE many will find the investigative approach of our group somewhat unusual, I shall first attempt to elucidate the factors necessitating the procedure which we have followed. At the time we started our study on plasma volume expansion, certain unquestionable facts had been established. The first was that shock was frequently associated with decreased plasma volume and the second was that any substance which would expand and maintain plasma volume would often bring about relief of shock. The third established fact was the practical consideration that most of the substance used previously resulted in storage of the material in the body or in functional impairment of one or more organs. To reach a solution in this problem it was necessary to find a substance which was capable of remaining in the blood stream, maintaining the vascular volume, and eventually being excreted or metabolized. Glycogen appeared to answer our demands, and