枯草培養に於けるゾウリムシの密度を限定する諸要素に就いて

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Time course of change in density of Paramecia rared in the bacterial suspension of hay infusion was observed, and the factors limiting its density were studied. The following results were obtained. 1) Density of Paramecia decreases a little soon after inoculation, then increases logarithmically, attaining certain steady level, and finally decreases to zero. 2) There is an optimal concentration of bacteria as food (Fig.1). 3) Volume of culture medium affects little on the steady level of density of Paramecia, although the maximal density is sometimes slightly higher in the culture of higher density (Fig.2). 4) Increase in inocular density of Paramecia caused, within a certain limit, slower multiplication. The greater is the maximal density, the shorter the steady level becomes and the more rapidly the density decreases. Excess inocular density inhibits completely the reproduction. Therefore an increase in population density seems to be one of limiting factors of reproduction (Fig.3). 5) Another factor limiting reproduction of Paramecium appears to be the change of physical and chemical properties of medium caused by coexistence of Paramecia and bacteria. Infusion containing only bacteria appears to possess a factor inhibiting reproduction of Paramecium but none inhibiting its existence, and a medium containing Paramecium as well as bacteria appears to have both of them (Fig.4).
社団法人日本動物学会の論文
1952-12-15