The sieve-tubes, with their accompanying parenchyma or stereom, constitute the tissue called phloem.
Incomplete fusion occurs in sieve tubes.
In the evening the milk is strained through a wire sieve and transferred to barrels.
The companion cells are cut off from the same cells as those which unite to form the sieve tube.
When the sieve-tube has ceased to function and the protoplasm, slime strings, and callose have disappeared, the perforations through which the slime strings passed are left as relatively large holes, easily visible in some cases with low powers of the microscope, piercing the sieve.plate.