1. 1.

    The elimination of CO2 through the lungs and skin of Xenopus laevis and its distribution between plasma and erythrocytes were determined during breathing and submergence periods.

  2. 2.

    CO2 output does not decrease during submergence, as lack of lung ventilation is compensated by an increase in cutaneous exchange. The total CO2 carried in the blood decreases after a 30 min dive, but the fraction carried in red blood cells increases substantially, due to an increase in the haematocrit values. This increase is related to a decrease in plasma volume during diving.

  3. 3.

    During short dives the blood shows changes characteristic of respiratory acidosis but longer dives result in a combination of respiratory and metabolic acidosis.

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