SUB-CLASS V 



CYANOPHYCE^ 



THE primitive forms of Algae classified under this 

 name possess in all cases a thallus of much sim- 

 plicity, being unicellular, or composed of single rows 

 of cells, nearly always embedded in definite gelatin- 

 ous sheaths or gelatinous masses of indefinite out- 

 ward form. The individual plants are in most cases 

 associated together in colonies, the tendency to form 

 gelatinous envelopes causing them to cohere in this 

 fashion. Reproduction is typically a process of 

 division of the thallus cells, though the precise 

 mode of it, and of the liberation of the propagative 

 bodies so formed, varies in the groups into which 

 the Cyanophycccv are divided. In Chroococcaccce the 

 cells are transformed into sporangia. A power of 

 movement is exhibited, in the absence of cilia, by 

 many members of the group, especially in the pro- 

 pagative cells, but this power is sometimes retained 

 by the mature thallus, as in the case of Oscillaria. 

 The colouring matter of the cells is a bluish-green 

 substance, phycocyanine, in addition to chlorophyll. 



