148 



FRESH-WATER BIOLOGY 



98 (99) Cells at the ends of, or distributed along rather firm, often lamellate 



gelatinous strands Hormotila Borzi. 



Chromatophore single, granular, without a pyrenoid. Re- 

 production by cell division, also by bi-ciliate zoospores, eight 

 of which are formed in a single zoosporangium. The zoospo- 

 rangia are much larger than the vegetative cells. 



FIG. 156. Hormotila mucigena Borzi. X 268. (After West.) 



99 (98) Cells distributed throughout a structureless, cylindrical, branched 



gelatinous colony. . ..'. ; ". . . . Palmodactylon Nageli. 



Cells spherical; gelatinous tubes branched or 

 unbranched, single or in clusters. Division of 

 cells first in one, later in three directions. 

 Chromatophore parietal and often lobed. 



The elongated shape of these colonies is 

 thought by West to be due to divisions occur- 

 ring more frequently in one direction than in 

 others. The plant occurs in swamps and quiet 

 waters. 



FIG. 157. Palmodactylon sp. Portion of young 

 colony. X about 600. (Original.) 



100 (97) Cells two or four in series, at the ends of attached, dichotomously 



branched stalks; chromatophores several. 



Mischococcus Nageli. 



Chromatophores one to four, without pyrenoids. Reproduction by 

 zoospores and isogametes which may or may not unite before germina- 

 tion. 



FIG. 158. Mischococcus confcroicola Nageli. X about 1 80. (After Rabenhorst.) 



101 (97, 100) Cells in radiating series, often branched, held together by 



gelatinous strands Dictyocystis Lagerheim. 



Chromatophore single, central, and radial. Reproduction probably by division. 



Though Dictyocystis is reported by several botanists, it seems a somewhat doubtful genus. 



102 (96, 107) Cells at the surface of an invisible gelatinous mass and 



borne on fine, radiating gelatinous strands 104 



103 (104, 105, 106) Cells reniform, four on a stalk, two borne near the adjoin- 



ing ends of the other two. . . Dimorophococcus A. Braun. 



Chromatophore single and parietal, each group of 

 cells formed by the internal division of a single mother 

 cell. 



The filaments which bear the cells are thought by some 

 to be formed from the remnants of the mother membrane, 

 but this needs further investigation. Large colonies may 

 become fragmented into smaller colonies. This alga is 

 not very frequent, and occurs in larger lakes rather than 

 in stagnant water. 



FIG. 159. 



Dimorphococcus lunatus A. Braun. 

 (Original.) 



X 600. 



