ISO 



FRESH-WATER BIOLOGY 



113 (114) Cells spherical Gloeocystis Nageli. 



The enveloping gelatinous substance showing a concentric lamellate structure. 



Reproduction by repeated cell division, several generations of cells often re- 

 maining enclosed in the original mother-membrane. According to some 

 authors reproduction also occurs by bicilliate zoospores. 



The authenticity of this genus is doubtful as the non-motile stage of certain 

 species of Chlamydomonas answers this description. 



Fig. 163. Gloeocystis vesiculosus Nageli. X 150. (After Nageli.) 



114(113) Cells elongated Dactylothece Lagerheim. 



. C:^-\ Chromatophore a parietal plate lying only on one side of the cell; no pyrenoids. 



As ii'^'i Gelatinous substance often lamellate. 



Fig. 164. Daclylothece braunii Lagerheim, X about 370. (After Lagerheim.) 



IIS (112) Gelatinous envelop not containing concentric lamellae about the 

 cells. . . ... 116 



116 (117) Gelatinous mass containing segments of the antecedent mother 

 cell Schizochlamys A. Braun. 



Cells spherical, scattered in a gelatinous mass together 

 with the visible remnants of the old membranes which 

 are split into distinct segments. 



West believes that it is the formation of the large amount 

 of gelatinous material that causes the firmer portion of 

 the membrane to become ruptured, and that this takes 

 place previous to the formation of the two or four daughter 

 cells. 5. gelatinosa is the only species reported in 

 America, and this occurs as a pale green irregular mass 

 either free or adhering to water plants. 



Fig. i6s. 



Schizochlamys gelatinosa A. Braun. 

 (Original.) 



X 600. 



117 (116) Gelatinous mass not containing segments of the antecedent mother- 

 membrane 118 



118 (119) Cells throughout the gelatinous mass formed by the outer layers 



of the cell walls Palmella Lyngbye. 



Chromatophore parietal, with a pyrenoid. Reproduction by division in three directions, 

 and according to Wille, by macrozoospores, microzoospores, and isogametes. 



119 (118) Cells at the surface of the gelatinous mass. 



Dictyosphaeropsis Schmidle. 



Cells free or attached, round or elongated. One or two disc-shaped, 

 parietal chromatophores present. Reproduction not well known. 



Fig. 166. Dictyosphaeropsis polatina Schmidle. X 37S- (After Schmidle.) 



HO f 1 11) Cells in clusters, usually of eight, sometimes four or sixteen ; colonies, 

 mostly floating 121 



