Figure 207 



HOW TO KNOW THE FRESH-WATER ALGAE 



294a A linear series of globular or oblong cells within a gelatinous 

 matrix, chromatophores star-shaped. Fig. 207 . . . ASTEROCYSTIS 



Fig. 207. Asterocystis smaiagdina 

 (Reinsch) Forti. 



The bright blue-green, star- 

 shaped chromatophores of this 

 species (the globose or oval cells 

 being enclosed in a wide gelatin- 

 ous sheath) help to identify this 

 branched filamentous alga. It is 

 a member of the Rhodophyta; usu- 

 ally occurs as an epiphyte on larger filamentous algae but may appear 

 in mixtures of free-floating forms. 



294b Two to four, or eight globose or oval cells contained within an 

 enlarged mother-cell wall; chromatophore-like bodies vermiform 

 (few and long, or many and short). Fig. 208 GLAUCOCYSTIS 



Fig. 208. a, b, Glaucocystis duplex 

 Presc; c, G. Nostochinearum Itz. 



There are apparently 2 or 3 spe- 

 cies of this genus which like Gioe- 

 ochaete (Fig. 206) involve an endo- 

 phytic blue-green alga and a col- 

 orless member of the Oocystaceae 

 (Fig. 85). The protoplasts are 

 bright blue-green and occur in dif- 

 ferent shapes and arrangements within either globose or oval cells, 

 according to species. The plants are free-floating in the tychoplank- 

 ton near shore or in shallow water habitats of swamps and bogs. 



295a (292) Cells in compact, irregularly shaped colonies, appearing 

 brown or orange-colored because of dark mucilage. See Fig. 

 49 BOTRYOCOCCUS 



295b Cells not in opague or orange-colored colonies as above; contents 

 red, violet-red, or green with a red tinge 296 



296a Living in snow in alpine regions (red snow). See Fig. 57 



CHLAMYDOMONAS 



296b Not living in snow 297 



297a A colony of oval or globose cells inclosed in a layered sheath. 

 See Fig. 41 GLOEOCYST1S 



297b Cells not in colonies; sheath not layered 298 



Figure 208 



129 



