The asexual cells are termed tetraspores on account of the usual occurrence of four in each sporangium.

The outer walls of the sporangium now become hard, and the whole falls off as a seed.

Aplanospores would seem to represent zoospores arrested in their development; without reaching the stage of motility, they germinate within the sporangium.

The spores are formed in a manner very similar to those of the mosses, and are set free by rupture of the sporangium.

From each locule of a plurilocular sporangium there is set free an oosphere, which, being furnished with a pair of cilia, swarms for a time.