ALG.-E CONTIiVUED: CLASSIFICATION. 



163 



Class Schizophyceae ( = Cyanophyc:e<-E). 



351. The Blue Ureen Algae, rir Cyanophyceae form slimy looking thin 

 mats on damp wood or the ground, or floating mats or scum on the water. 

 The color is usually bluish green, but in some species it is purple, red or 

 brown. All have chlorophyll, but it is not in distinct chloroplasts and is 

 more or less completely guised by the presence of other piigments. Two 

 orders and eight families are recognized. The following include some of 

 our common forms: 



352. ORDER COCCOGONALES (COCCOGONEa;).— Single-celled plants, 

 occurring singly or in colonies, in some forms 

 forming short threads. One of the two fami- 

 lies is mentioned. 



353. Family Chroococcacege. — The plants 

 multiply only through cell division. Chroococ- 

 cus, forms rounded, blue-green cells enclosed 

 in a thick gelatinous coat, in fresh water and 

 in damp places; certain spei ies form "lichcn- 

 gonidia" in some genera of lichens. Gla'o- 

 capsa is similar to Chroococcus, but the col- 

 onies are surrounded bv an additional common 

 gelatinous envelope (fig. 16S); on damp rocks, 

 etc. 



354. ORDER HORMOGONALES (HORMOGONEa;).— Plants filamentous, 



simple celled or with false 

 or true branching, usually 

 several celled (Spirulina is 

 single celled). Multiplica- 

 tion takes place through 

 Iwrmogoiies, short sections 

 of the threads becoming 

 free; also through resting 

 cells. Two of the six fami- 

 lies are mentioned. 



355. Family OsciUatorl- 

 acege. — This family is rep- 

 resented by the genus Oscil- 



-^. , latoria, and by several other 

 Fig. 160. ' ^ , . , , 



A, Oscillatnna princeps, a terminal cell, b. c. genera common and widely 



portions from the middle of a filament. In c, a distributed. Oscillatoria 



dead cell is shown between the livmg cells; b, 



Oscillatoria froelichii, b, with granules along the contains many specieS. 



partition walls. r^^^^, ^^^ f^,^j^^j ^^ ^^^ 



ijamp ground or wood, or floating in mats in the water. The)- often forrn on 



Fig. 168. 

 Glceocapsa. 



