SOME EFFECTS OF TEMPERATURE ON THE FREQUENCY OF DIVISION AND ON THE VOLUME OF STARCH AND FAT IN CHILOMONAS PARAMECIUM

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1. Chilomonas paramecium was grown in a solution of inorganic salts plus sodium acetate, and the effect of temperature on the frequency of division and on the volume of starch and fat measured. 2. As the temperature rises the frequency of division increases from zero at 9.5° C. to a maximum at 27°-30° C. and then decreases to zero. 3. When chilomonads are transferred from low temperatures to higher temperatures, a period of about 48 hours is required before the frequency of division increases to the value characteristic of the higher temperature. 4. When chilomonads are exposed to the low temperature of 9.5° C. for prolonged periods, then transferred to higher temperatures, the lethal high temperature and the period required to kill the organisms decrease. This indicates that the low temperature modifies the organisms and that the modified condition persists for some time. 5. At all viable temperatures, the volume of starch and fat per chilomonad remains constant, but as the temperature rises from 9.5° C., the volume of starch and fat synthesized increases, reaching a maximum at 30° C. 6. When organisms are exposed to lethal high temperatures there is an increase in the volume of both starch and fat. This is undoubtedly due to the fact that synthesis at these temperatures is not greatly impeded, that division decreases or ceases, but that the organisms live for a time and accumulate some starch and fat. 7. At lethal low temperatures, division ceases, there is a gradual decrease in the volume of starch accompanied by an insignificant increase in the volume of fat. 8. In solutions without sodium acetate, there is a decrease in the volume of starch to zero, an initial increase and a subsequent decrease in the volume of fat to zero. This process is identical at all viable temperatures but proceeds faster at the higher temperatures. 9. Synthesis of starch and fat by starved chilomonads in acetate ammonium solution is rapid and varies directly with the temperature. 10. The method of observing and measuring the volume of starch and fat has several drawbacks but does indicate changes with some accuracy. 11. The volume of starch and fat may indicate the metabolic rate of the organisms. Chilomonads living in an environment optimum for nutrition and temperature are filled with starch and fat and probably have a characteristic metabolic rate resulting from a balance in the rates of synthesis and decomposition of starch and fat. Changes in the environment may result in the breakdown of the balance, change in the volume of starch and fat, and probably a change in the metabolic rate.