An as yet unidentified glucose-complex is formed in the cells of 5 mm stem segments cut from the third internode at 1 mm from the tip of etiolated pea seedlings. In segments growing in solutions containing 10 ixg/ml IAA and various concentrations of glucose the quantities of the unknown glucose-complex and cellulose are proportional. Increasing the IAA concentration at a constant glucose concentration of 0.1 % causes an increase in the glucose-complex and in the synthesis of cellulose up to a concentration of 10 ag/ml. At IAA concentrations higher than 50 ixg/ml cellulose synthesis decreases to the value obtained when no IAA is present, whereas the amount of the glucose-complex is increased. Galactose inhibits cellulose synthesis by way of interfering with the glucose absorption. In low concentrations of glucosecobalt chloride promotes sugar absorption, the formation of the glucose-complex, and cellulose synthesis. In high sugar concentrations it does not affect these processes. The results obtained indicate a close relationship between cellulose synthesis and the formation of the glucose-complex. It is suggested that the latter is an intermediate in the synthesis of cellulose.