Coleochaete sp., growing as a plate.
In the zoosporangia of Oedogonium, Tetraspora and Coleochaete the contents become transformed into a single zoospore.
Again, in oogamous reproduction, while in general only one oosphere is differentiated in the oogonium, in Sphaeroplea several oospheres arise in each oogonium; and while the oospheres usually contract away from the oogonial wall, acquiring for themselves a new cell-wall after fertilization, in Coleochaete the oosphere remains throughout in contact with the oogonial wall.
In Coleochaete the oogonial wall is drawn out into a considerable tube, which is provided with an apical pore, and this tube has a somewhat similar appearance to the imperforate trichogyne of Florideae to be hereafter described.
Such are Coleochaete, Oedogonium, Cylindrocapsa, Ulothrix, Vaucheria, Volvox, &c. In others only the asexual method is yet known.
It is held that in Coleochaete a parenchyma results from the division of the oospore, from each cell of which a zoospore arises.
Coleochaete sp., zoospore.
Coleochaete sp., with antheation.
Coleochaete sp., fertilized egg tion.
In Coleochaete this seems to be preceded by the formation of a minute parenchymatous mass, in each cell of which a zoospore is produced.
In Sphaeroplea it is only at this stage that zoospores are formed at all; but in most cases, such as Oedogonium, Ulothrix, Coleochaete, similar zoospores are produced again and again upon the thallus, and the product of the oospore may be regarded as merely a first brood of a series.
Such are Coleochaete, Ochlochaete, Elachistea, Ascocyclus and Rhododermis.