Seasonal Variation in the Respiratory Acclimatization of the Leech Erpobdella Testacea (Sav.)

Abstract

1. In summer the leech Erpobdella testacea becomes acclimatized to a low concentration of oxygen in the water, and can maintain a constant rate of oxygen consumption down to one-third air-saturation. This acclimatization does not occur in winter. 2. The mechanism of acclimatization is such that it can operate when the leeches are resting, and when the haemoglobin has been prevented from functioning by treatment with carbon monoxide. 3. In the course of normal respiration in air-saturated water at 20° C. about 45% of the oxygen is transported to the tissues by the haemoglobin. In one-third air-saturated water about 25% is transported in this way. 4. After a meal of Tubifex the oxygen consumption increases threefold, and declines to the previous level over a period of 4 days. 5. A polarographic respirometer embodying a wide-bore dropping mercury electrode has been developed for this work. It provides on a galvanometer a constant indication of the oxygen concentration in the water which has passed over the animals.