SUB-CLASS II 



CELOROPHYCE^ 



THE ChloropJiycecc attain their finest development 

 in fresh waters, but representatives of most of the 

 orders occur in the sea. The multicellular forms 

 never attain a higher stage of development than 

 branched or simple cell-rows or flat expanses of 

 indefinite form. The unicellular forms, however, in 

 addition to the simple Algae usually so called, are 

 represented by the multinucleate orders in which the 

 highly developed thallus is a conspicuous feature. 



Oogamous reproduction occurs here, as in the 

 Phceophycece, but mostly in fresh-water forms. It is 

 represented in the sea in the marine species of 

 Vaucheria only, and this type of oogamous reproduc- 

 tion differs from that of Phceophycece (Fucacecc) in 

 respect of the fact that the fertilised oosphere is not 

 extruded but remains in situ in the parent plant. 

 The fact of the occurrence of this high type of 

 reproduction almost exclusively in fresh-water forms, 

 and in those Algae with chromatophores most nearly 

 resembling terrestrial vegetation, points to this group 



