Fink ( '25) studied the respiratory metabolism of the Japanese beetle egg at temperatures between 21" and 24°C. He found that at these temperatures, the respiratory rate remained low during the first 6 days and then increased rapidly. He called the first 6 days of the embryonic period the "formative period. " Rothstein ( '52) studied biochemical changes occurring during the embryonic development of this insect at 30°C. and made a fern observations on the rate of oxygen consumption. At this higher temperature the formative period lasts 4 days (newly-laid t o 3-day egg). Rothstein found that glycogen serves as the source of energy during the period when the rate of oxygen consumption is low, and that free fat is used during the remainder of the embryonic period. The first 4 days of embryogenesis at 30°C. are also characterized by a rapid increase in weight due to the imbibition of ~a t e r , the weiglit then remaining approximately constant until the time of hatcliing. Ludwig and Rothstein ('52) found a rapid increase in the nitrogen content of the water-This investigation was supported in part bp tlic Medical Research aid Development Board, Office of the Surgeon General, Department of the Army, under Contract No. DA-49 007-MD-444.