Osmotic Regulation in the Frog, Kana Esculenta (L.), at Low Temperatures

Summary. When frogs in water are transferred from room temperature to low temperatures, e.g. 2–3° C, the body water increases rapidly in amount until a new equilibrium is established within some few days. Further weight increase, e.g. increase in body water may occur at a low rate. This slow working part of the water retention goes parallel to a salt accumulation brought about by active uptake of NaCl through the skin from the surrounding water. Injected water is also rapidly eliminated by the kidneys in frogs living at low temperatures. Salt administered in form of hypertonic solution of NaCl is, however, not eliminated by the kidneys. The water and salt accumulation demonstrated in frogs at low temperatures is therefore probably caused by an inability of the kidney to excrete the salt taken up through the skin, the resulting hypertonicity of the blood being counteracted by retention of some of the water entering through the skin.