GROUP I. THALLOPHYTA: ALGJ: : CHLOROPHYCE^. 



239 



whole protoplasm of the body, iu the latter from that of successive branches of 



FIG. 169. Vauclieria sessilis (x 30). A sp A newly-formed zoogonidium. B A resting 

 zoogonidium. C, The commencement, 1) and E more advanced stages, of germination ; 

 sp zoogonidium; s apex of the green filament; w a colourless adventitious root. F Fila- 

 rneut with sexual organs ; og oogonium : 7i antheridiuoi after rupture. (After Sachs.) 



FIG. 170. Acetabularia crenulata (after Kiitz- 

 ing; nat. size): the terminal circular disc con- 

 sists of a whorl of coherent leaves 5 in these 

 the gametangia are formed. 



FIG. 171. JBotrj/cJiiim granulatum 

 (x 6): s the green shoot; w the 

 colourless root. 



