cyclosis [key], streaming of cytoplasm within a living cell without deformation of the external cell membrane. In some plant cells there is a rapid rotatory cytoplasmic movement, which is limited to the peripheral parts of the cell next to the cell wall; chloroplasts and granules move in this stream. This movement may be increased by light, and is dependent on temperature and pH. Auxins, or growth hormones, may also increase the rate of movement. Specialized cell components, microtubules, may direct the flow or may serve as a framework upon which the streaming occurs. Examples of cells in which cyclosis can be seen are the leaf cells of small aquatic plants, such as Elodea, and root hair cells of many plants. In some protozoans, e.g., the ciliates, slower cyclotic movements transport digestive vacuoles through the cell body.
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