218 PROTOZOOLOGY 



reproduction and palmella formation known; sexual reproduction 

 isogamy or anisogamy ; fresh water. Numerous species. 



C. monadina Stein (Fig. 96, a-c). 15-30/x long; fresh water; 

 Landacre noted that the organisms obstructed the sand filters used in 

 connection with a septic tank, together with the diatom Navicula. 



C. angulosa Dill. About 20/i by 12-15^; fresh water. 



C. epiphytica Smith (Fig. 96, d). 8-9fi by 7-8m; in freshwater lakes. 



C. globosa Snow (Fig. 96, e). Spheroid or ellipsoid; 5-7/x in dia- 

 meter; in freshwater lakes. 



C. gracilis S. (Fig. 96,/). 10-13m by 5-7/x; fresh water. 



Genus Haematococcus Agardh (Sphaerella Sommerfeldt). Sphe- 

 roidal or ovoid with a gelatinous envelope; chromatophore peripheral 

 and reticulate, with 2-8 scattered pyrenoids; several contractile 

 vacuoles; haematochrome frequently abundant in both motile and 

 encysted stages; asexual reproduction in motile form; sexual repro- 

 duction isogamy ; fresh water. 



H. pluvialis (Flotow) (Figs. 40; 96, g). Spherical; with numerous 

 radial cytoplasmic processes ; chromatophore U-shape in optical sec- 

 tion; body 8-50/1, stigma fusiform, lateral; fresh water. Reichenow 

 (1909) noticed the disappearance of haematochrome if the culture 

 medium was rich in nitrogen and phosphorus. In bacteria-free cul- 

 tures, Elliott (1934) observed 4 types of cells: large and small flagel- 

 lates, palmella stage and haematocysts. Large flagellates predominate 

 in liquid cultures, but when conditions become unfavorable, palmella 

 stage and then haematocysts develop. When the cysts are placed in 

 a favorable environment after exposure to freezing, desiccation, etc., 

 they give rise to small flagellates which grow into palmella stage or 

 large flagellates. No syngamy of small flagellates was noticed. Hae- 

 matochrome appears during certain phases in sunlight and its ap- 

 pearance is accelerated by sodium acetate under sunlight. 



Genus Sphaerellopsis Korschikoff (Chlamydococcus Stein). With 

 gelatinous envelope which is usually ellipsoid with rounded ends; 

 body elongate fusiform or pyriform, no protoplasmic processes to 

 envelope; 2 equally long flagella; chromatophore large; a pyrenoid; 

 with or without stigma; nucleus in anterior half; 2 contractile vacu- 

 oles; fresh water. 



S. fluviaiilis (Stein) (Fig. 96, h). 14-30m by 10-20m; fresh water. 



Genus Brachiomonas Bohlin. Lobate; with horn-like processes, 

 all directed posteriorly; contractile vacuoles; ill-defined chromato- 

 phore; pyrenoids; with or without stigma; sexual and asexual re- 

 production ; fresh, brackish or salt water. 



