cyclosis cy·clo·sis (sī-klō'sĭs)
n. pl. cy·clo·ses (-sēz)
The streaming rotary motion of protoplasm within certain cells and one-celled organisms.
the movement of the fluid substance (cytoplasm) within a plant or animal cell. The motion transports nutrients, proteins, and organelles within cells. First discovered in the 1830s, the presence of cytoplasmic streaming helped convince biologists that cells were the fundamental units of life.
Learn more about cyclosis with a free trial on Britannica.com.