Abstract
A summary is presented of the initial experiments of a series which is planned to elucidate, if possible, some of the complex factors at work in a “hay infusion”; for example, such as those which determine the inter-dependence of the organisms, their sequence, time of appearance, disappearance, etc. The data outlined were derived from the study of: (a) the effect of different volumes (2, 5, 20 and 40 drops) of culture medium on the rate of reproduction of Paramaecium; (b) the effect of changing the culture medium daily and on alternate days on the rate of reproduction of Paramaecium; and (c) the effect of culture medium, in which large numbers of paramæcia have been living, on the rate of reproduction of Paramaecium. It is believed that the results obtained justify the following conclusions:
1. The rate of reproduction of Paramaceium aurelia and Paramaecium caudatum is influenced by the volume of the culture medium, within the limits tested, and the greater the volume the more rapid is the rate of division.
2. Paramæcia excrete substances which are toxic to themselves when present in their environment, and these substances are more effective when the organisms are confined in limited volumes of culture fluid.
3. The excretion products of paramaecia play an appreciable part in determining the period of maximum numbers, rate of decline, etc., of this animal in “hay infusions.”
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