PHYGOPHYTA. 



159 



about its smaller hyaline end, by means of which it swims 

 rapidly hither and thither in the 

 water (C). After a time it 

 comes to rest, clothes itself with 

 a cell-wall, and sends out from its 

 smaller end root-like prolonga- 

 tions (D), which attach it to 

 some object; it now elongates, 

 and at length forms partitions, 

 taking on eventually the form 

 of the adult filament. It some- 

 times happens that before the new 

 plant resulting from the growth 

 of a zoospore has formed its first 

 partition the protoplasm again 

 abandons its cell, to be for a second 

 time a zoospore (E). 



283. In the sexual reproduction 

 of the plants of this class the 

 female organ consists of a rounded 

 germ-cell situated within a cavity 

 — the oogone ; it is developed from 



one of the cells (sometimes two) pio. 87.-Asexual reproduo- 



of the filament by a condensing IZVotVmiZ^tt- b%'^^; 

 and rounding off of the proto- ll TzolpX;^?, swiSmtaS 



, . . , , , , zoospore ; D, zoospore at rest 



plasmic contents ; when the germ- and sending out root-like pro- 



. longations from the hyaline 



cell IS fully mature, an openins: end ; E, a young plant com- 



^ ° posed of only one cell, with 



is formed in the oogone wall for ^^ nraed'^times ®^''*p"'^- 

 the ingress of the antherozoids (A 



and J3, Fig. 88). One or more antherozoids are produced 

 in certain small cells of the same or another filament; in 

 shape they resemble the zoospores mentioned above. 



