258 THE MICROSCOPE AND ITS REVELATIONS. 



Observations of an analogous character were previously made by Cohn 

 and Itzigsohn. 



255. In their generative process, also, the (Edogoniece show a curious 

 departure from the ordinary type; for whilst the ' oospores ' are formed 

 within certain dilated cells of the ordinary filament (Fig. 151, A, i), and 

 are fertilized by the penetration of ' antherozoids ' (2), these antherozoids 

 are not the immediate product of the sperm-cells of the same or of 

 another filament, but are developed within a body termed an ' andro- 

 spore' (5), which is to be set free from within a sperm-cell (4), and 

 which, being furnished with a circular fringe of cilia, and having motile 

 powers, very strongly resembles an ordinary zoospore. This androspore, 

 after its period of activity has come to an end, attaches itself to the outer 

 surface of a germ-cell, as shown at I, b ; it then undergoes a change of 

 shape, and a sort of lid drops oif from its free extremity as seen in the 

 upper part of I, by which its contained antherozoids (2) are set free; and 

 at the same time an aperture is formed in the wall of the germ-cell, by 

 which the antherozoid enters its cavity, and fertilizes its endoplasm by 

 dissolving upon it and blending with it. This mass then becomes an 

 oospore (3), invested with a thick wall of its own, but still retains more 

 or less of the envelope derived from the cell within which it was devel- 

 oped. ' It is probable that the same thing happens in many Conf ervaceas, 

 and that some of the bodies which have been termed ' micro-gonidia ' are 

 really androspores. The offices of these different classes of reproductive 

 bodies are only now beginning to be understood; and the inquiry is one 

 so fraught with Physiological interest, and, from the facility of growing 

 these plants in Aquaria, may be so easily pursued, that it may be hoped 

 that the zeal of Microscopists will not long leave any part of it in 

 obscurity. 



256. The Chcetophoracem constitute a beautiful and interesting little 

 group of Confervoid plants, of which some species inhabit the sea, whilst 

 others are found in fresh and pure water, rather in that of gently mov- 

 ing streams, however, than in strongly flowing currents. Generally 

 speaking, their filaments put forth lateral branches, and extend them- 

 selves into arborescent fronds; and one of the distinctive characters of 

 the group is afforded by the fact, that the extremities of these branches 

 are usually prolonged into bristle-shaped processes (Fig. 151, B). As in 

 many preceding cases, these plants multiply themselves by the conversion 

 of the endochrome of certain of their cells into ' zoospores;' and these, 

 when set freeware seen to be furnished with four flagella. 'Kesting- 

 spores ' have also been seen in many species; and it is probable that these, 

 as in ConfervacecB, are really oospores. 



257. The Batrachospermece, whose name is indicative of the strong 

 resemblance which their beaded filaments bear to frog spawn, are now 

 ranked as humble fresh-water forms of a far higher marine group of 

 Algae, the Rhodospermem or Bed Sea-weeds ( 330). But they deserve 

 special notice here on account of the simplicity of their structure, and 

 the extreme beauty of the objects they afford to the Microscopist (Fig. 

 152). They are chiefly found in water which is pure and gentle-flowing. 

 " They are so extremely flexible," says Dr. Hassall, " that they obey the 

 slightest motion of the fluid which surrounds them; and nothing can 

 surpass the ease and grace of their movements. When removed from the 



1 See Pringsheim in "Ann. des Sci. Nat.," 4eme Ser., Botan., Tom. v. (1856), 

 p. 187. 



