718 



SYSTEMATIC BOTANY. 



filamentous thallus, and of a reddish-purple, rose-coloured, 

 or reddish-brown colour. Reproduced by, 1. Tetraspores 

 {figs. 831—833) ; 2. Spores {figs. 834 and 835) ; and 3. An- 

 theridia. (See pp. 390, 391.) 



Examples : — Corallina, Plocaria, Chondrus, Callithamnion, 

 Ceramium, Porphjra. 

 Sub-order 3. ChlorosporecB, Conferv ndeoe, or Green-coloured 

 Algce. — Unicellular or multicellular Algas, growing in fresh 

 or salt water, or in moist situations ; usually of a bright green 

 colour, or rarely red. Reproduced by, 1. Spores, formed 

 either by conjugation (figs. 828 and 829), or by impregnation 

 from spermatozoids ; and, 2. Zoospores {figs. 14, 15, 146, 829 

 and 830). (See pp. 388—390.) 

 Sub-order 4. Diatomacece. — Brittleworts.— The following diag- 

 nosis is from Henfrey : — " Microscopic unicellular plants, 



occurring isolated or in 

 Fig. 1095. groups of definite form, 



usually surrounded by a 

 gelatinous investment, 

 the cells exhibiting more 

 or less regular geome- 

 trical outlines and en- 

 closed by a membrane, 

 striated {fig. 1095) or 

 granular, either simply 

 tough and continuous 

 {fig. 1096), or impreg- 

 nated with silex and 

 separable into valves 

 {fig. 1095). Reproduc- 

 tion by spores formed after conjugation of the cells {fig. 

 1096), by zoospores formed from the cell contents, and by divi- 



Fig. 1095. A species of Diatomaceous Alga 

 (^Diatoma marinum), dividing into parts by 

 merismatic or Jissiparous cell-diviaion. The 

 parts are seen to be striated. 



Fig. 1096. 



Fig. 1096. Two Desmidiaceous Algse {Docidium Ehrenbergii) after conjuga- 

 tion, with a resting or inactive spore between them. After Ralfs. 



sion." The Diatomaccaj are again divided into two sections : 

 1. Diatomece {fig. 1095). Natives of fresh or salt water, of a 



