Paramecium

Paramecium, or SLIPPER ANIMALCULE, an Infusorian very common in pond water or in vegetable infusions. In shape it is an asymmetrical oval, in length about $\backslash frac\{1\}\{100\}$ of an inch. If dry grass be steeped in a glass of water for some days, the animalcules dormant about the stems revive and multiply very rapidly. Each paramecium is covered with rows of cilia which lash it through the water and drive food-particles into an aperture which serves as mouth. As the food-particles enter they take bubbles of water with them, and are moved round and round in the living substance until they are digested or got rid off. There are two (excretory) contractile vacuoles; the large nucleus has a small one (paranucleus) lying beside it; beneath the thin rind there are remarkable eversible threads. A paramecium often divides transversely into two; these two repeat the process, and with continually diminishing size rapid multiplication may thus proceed for a while. It has its limits, however, and then two individual Infusorians conjugate, exchange some of the material of their paranuclei, and separate. Thus they seem to renew their youth.