44 



PLANT-LIFE 



monest of the green fresh-water Algae. Unlike Ulothrix, 

 they seem to prefer still water, such as occurs in ponds 



and water-butts ; they 

 frequently turn up in 

 the standing water of 

 aquaria attached to the 

 glass. The thallus is an 

 unbranched filament 

 composed of a single row 

 of cells. The basal cell 

 o is not so deeply pig- 



Fi6. 13. — CEdogonidm cttjIatum ; 

 Small Female Plant, x 166. 

 6, Attachment disc; §> 5 , oogonia, the 

 upper one opening by a lid — it con- 

 tains a fertilized egg-ceU ; the lower 

 oogonium closed — it contains un- 

 fertilized egg-cell. J , J , dwarf 

 males, the upper one opened so as 

 to discharge a spermatozoid. 



A 



Pig. 14. — (EDOGONnr-M orcLi- 

 TDM ; Zoospores, x 350. 

 A, Zoospore escaping from 

 mother-cell ; B, free zoospore 

 with fringe of ciha. 



mented with chlorophyll 

 as the others ; it is 

 specialized into a disc 

 of attachment, or a hold- 

 fast, by which the thread 

 clings to the surface of 

 stones, plants, etc. The 

 general appearance of a 



small female plant of 

 CEdogonium ciliatum, under high magnification, is re- 

 presented in Fig. 13. The apical cell in this species 



