196 



PRACTICAL BOTANY 



181. Cladophora: nutrition. Cladophora is well supplied 

 with the food materials that it needs. It grows chiefly in 

 movmg water, which is better aerated than still water. This 



Fig. 159. One of the filamentous algse (Uiothrix) 



A, the base of a plant showing the attaching or holdfast cell and a few vegetative 

 cells ; £, a group of vegetative cells ; '_', cells in which gametes have formed ; D, 

 two cells in which zoospores have formed, and one cell from which the zoospores 

 have escaped: J?, swimming zoospores; F, a, h, c, (/, gametes uniting to form a 

 zygospore; G, the zygospore, after a period of rest, grows and finally produces 

 zoospores ; H, a zoospore germinating to produce a new Uiothrix plant. All greatly 

 enlarged. E, F, and G after Dodel-Port 



water also carries in solution more or less inorganic sub- 

 stances from the soil. The holdfast usually holds the plant se- 

 curely in this favorable environment. Furthermore, its system 



