1. Osmotic pressures of urine removed from the crayfish antennal gland have been re-measured. The results fail to confirm those obtained earlier which indicated a marked fall in the distal portion of the antennal gland. The possible reasons for this discrepancy are discussed.
2. No significant fraction of the sodium in the urine is localized within the formed bodies found there. Potassium is localized within the formed bodies, but the relative amount cannot be ascertained.
3. There is an inverse relationship between sodium and potassium concentrations in the tubular (distal) portions of the antennal gland. No such relationship exists in the coelomosac and labyrinth (proximal) portions of the gland.