The average oxygen consumption of isolated hind femora of Melanoplus femur-rubrum was 180 cu.mm. per gram per hour; that of femora of M. differentialis was 197 cu. mm. per gram per hour. The average respiratory quotient of the latter was 0.82. In M. femur-rubrum 190 per cent of the oxygen debt incurred during anaerobiosis was repaid during recovery. In M. differentialis 125 per cent of the debt was repaid, and the carbon dioxide retained in the tissues during the recovery period was equal to the carbon dioxide produced during anaerobiosis. The end-products of anaerobiosis in grasshoppers are probably similar to those in vertebrates, but their removal seems to involve a greater expenditure of energy.