FILAMENTOUS GREEN ALG& 



22$ 



o i! 



Fig. 1 80. 



Stem of 

 aquatic plant, 

 showing Co- 

 1 eoc h ae te , 

 natural size. 



Fig. 181. 

 Thallus of Coleochaete scutata. 



flattened, more or less circular cell plates. Asexual repro- 

 duction is by biciliate zoospores, one each from a parent cell. 

 In sexual reproduction sperm 

 cases are formed in groups 

 of four, each one producing 

 a small biciliate sperm. The 

 egg cases (oogonia) are large 

 and possess a long slender 

 beak called a trichogyne. 

 The sperm becomes attached 

 to the trichogyne; its nu- Fig. 182. 



Fig. 183. 



Portion of thallus 

 of Co 1 eoc haete 



Portion of thallus of Co- scutata, showing 

 cleUS moves down the leochaete scutata, showing four antheridit 



empty cells from which formed from one 

 zoospores have escaped, thallus cell; a sin- 

 one from each cell; zoo- gle sperm at the right, 

 spores at the left. (After (After Pringsheim.) 

 eim.) 



tube, enters the egg and 

 fuses with the nucleus of 

 the egg. The egg after fer- 

 tilization becomes surrounded by an envelope of branches growing 

 from cells adjacent to the egg case, and then passes through a 

 resting^stage. When it germinates it produces a small mass of 



