The directional movement of cytoplasm in certain cells, which allows movement of substances through the cell, especially around the cell’s periphery. It has been observed most clearly in large cells, such as plant sieve elements and unicellular algae, in which simple diffusion is ineffective as a means of local transport in the cell. The mechanism of streaming involves the interaction of myosin motor proteins (attached to organelles) with actin microfilaments parallel to the direction of flow and requires energy from ATP. A similar streaming of cytoplasm is responsible for amoeboid movement.