OXYGEN CONSUMPTION AND CARBON DIOXIDE ELIMINATION IN TETRAHYMENA GELEII FURGASON

¹ Department of Physiology and Pharmacology, College of Pharmacy, University of Nebraska, Lincoln

1. Oxygen consumption and carbon dioxide elimination of Tetrahymena geleii has been ascertained for different temperatures, for different population densities, and for "young" and "old" cultures.

2. The tests were conducted in most of the experiments with washed organisms in inorganic buffer solution.

3. When "young" organisms are used, the oxygen consumption per unit volume of cell substance is inversely proportional to population density. The respiratory quotients for all tests were nearly always above 1.0.

4. When "old" organisms are used there is an increase in O₂ consumption per unit volume of cell substance with an increase in population density up to 69,000-72,600 organisms per ml. Densities above this result in lower consumptions. Respiratory quotients varied from an average of 1.11 in low population densities to 1.28 at optimum densities.

5. Oxygen consumption is always greater in the "young" cultures than in the "old" cultures, densities being equal.

6. With an increase in temperature, the O₂ consumption increases to a maximum at 25° C. in both "young" and "old" cultures. Above this temperature the consumption decreases. In all tests, from 10 to 35° C., R.Q. values were above 1.0.

7. "Young" organisms, tested in fresh solution of the same kind in which they were grown, 2 per cent proteose-peptone (Difco), show much greater O₂ consumption than those tested in inorganic buffer solution. "Old" organisms, however, tested in the same solution in which they had grown, have a lower O₂ consumption than old specimens tested in fresh inorganic buffer solution.

8. Very high respiratory quotients were obtained for the organisms in proteose-peptone, especially in "old" cultures where the average was 2.81.

9. In nitrogen gas with but minute traces of oxygen, Tetrahymena utilizes the small quantity present and gives off comparatively large quantities of carbon dioxide. The R.Q. values are extremely high.

10. Tetrahymena geleii is to a limited extent anaerobic but it can live only with difficulty for more than a few days in the absence of oxygen.