HOW TO KNOW THE FRESH-WATER ALGAE 



298a Cells spherical, solitary or gregarious, terrestrial, forming dark 



red patches on damp soil (common in green houses). Fig. 209. 



PORPHYRIDIUM 



Fig. 209. Porphyridium cruentum Naeg. 



\ 







On the damp soil of green houses 

 or on wet brick walks this plant often 

 forms purple, or wine-red gelatinous 

 films. It is a unicellular member of 

 the Rhodophyta which has a star-shaped 

 chromatophore. 



Figure 209 



298b Cells round, ellipsoid, or fusiform, not arranged as above. . . .299 



299a Cells fusiform; haematochrome coloring the green cell red; with 

 1 flagellum. See Fig. 8 EUGLENA 



299b Cells round or ellipsoid; protoplast with a wide wall which ap- 

 pears as a gelatinous sheath; flagella 2, but usually not showing 

 when cells are in an encysted condition at which time they ex- 

 hibit a red color. See Fig. 19 HAEMATOCOCCUS 



300a (291) Plants filamentous 301 



300b Plants not filamentous 304 



301a A false filament, consisting of branched tubes with 1 or 2 spherical 

 cells at the distal ends. Fig. 210 MISCHOCOCCUS 



Fig. 210. Mischococcus confervicola 

 Naeg. 



The globose, yellowish-green cells of 

 $(JD this species occur at the ends of re- 

 peatedly branched gelatinous stalks, 

 ~^. attached to filamentous algae. Only 1 



^©^ species is known from this country. 



Figure 210 



301b Plant a true filament 302 



130 



