360 FRESH-WATER ALGiE. [CJilofosjoermea. 



betwixt the cells. In the meantime^ if the plant be a Zj/g- 

 nema, the endochrome in the spiral tubes becomes confused, 

 and the contents of one cell pass through the connecting 

 tubcj and mingle with those of the other^ forming a circular 

 or oval body_, of a dark green colour. It is remarkable 

 that the cells of one part of the filament will part with 

 their contents and remain empty, while in another part of 

 the same filament, they will receive the contents of the cells 

 of another adjoining filament. 



Some of the species of the genus Zygnema do not thus 

 unite with other filaments ; the round dark-green granular 

 balls being in these formed by the union of the contents of 

 two adjoining cells in the same filament. When two cells 

 are thus conjugating, the cell which has the greater portion 

 of the matter receives the contents of the other. In the 

 course of a few days, the sjwrangiay or globules, are formed, 

 and are invested with two or three membranes, to preserve, 

 we doubt not, the vitahty of the seed. In a week or two the 

 tilaments separate, and break down at the joining of the cells, 

 and the zoospores bursting from them are disengaged and fall 

 to the bottom, to spring up after the rigour of winter, or even 

 durinir winter, when there is not a continuance of frost."^ 



* See a fuller and better statement of these matters in Ilassall's excellent 

 work on British Fresh-water Alf;a?. 



