Studies on the Adaptation of the Toad Bufo Viridis to High Salinities: Oxygen Consumption, Plasma Concentration and Water Content of the Tissues*

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Abstract
1. The toad Bufo viridis was adapted to various salinities up to 800 mOsm NaCl solutions. 2. The blood was always hypertonic to the external solutions and had a high urea concentration. Urea concentration in the plasma was higher in summer than in winter. Urine was hypotonic to the plasma in low salinities and became isotonic with the plasma at 400 mOsm and higher salinities. 3. Water content of the whole body and the skeletal muscles decreased somewhat with salinity. 4. Oxygen consumption was unaffected by salinity when animals were gradually adapted to high salinities. It increased, however, upon acute dehydration whether this was caused by immediate transfer to high salinity or by rapid evaporative dehydration in air. The adaptation of the toad to high salinities is discussed from the point of view of the effect of changes of the internal environment on various organs other than those concerned with osmoregulation.