The circulation of cytoplasm within cells. This is
especially true in plant cells where there are large vacuoles. Protoplasm flows
around the margins and in cytoplasmic strands that sometimes extend through the
vacuoles. Protoplasm in adjacent cells may flow in opposite directions, or it
may reverse directions in any particular cell. Light and temperature especially
influence this action in plant cells, but the exact cause of movement is
unknown. Circulation results in a thorough mixing of protoplasm and its
contents.
Cyclosis of protoplasm in palisade cells of leaves
may prevent the overexposure of chloroplasts to light, since they remain in a
position of maximum exposure only momentarily.
