HOW TO KNOW THE FRESH-WATER ALGAE 



341a (290) Plant a branched, feathery, gelatinous thallus, the proto- 

 plasts crowded in linear series with tough, tublular envelopes. 

 Fig. 241 HYDRURUS 



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Fig. 241. Hy drums foeti- 

 dus (Vill.) Trev. Cells 

 in mucilaginous tubes. 



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Gfc O <^C^^Q* :: Usually in high moun 



Figure 241 



tain streams, this organ- 

 ism forms stringy, brown, 

 gelatinous masses at- 

 tached to stones. The 

 bushy, yellow-green or brown tufts contain oval cells arranged in linear 

 series within gelatinous tube-like strands. Sometimes a small stream 

 will be actually choked with the dense growths. The disagreeable odor 

 these plants have is responsible for the specific name. The cells may 

 change into rather curiously shaped, pyramidal zoospores that have 

 but one flagellum. 



341b Plant not a feathery, gelatinous thallus 342 



342a Sparsely branched, sedentary filaments. Fig. 242 



PHAEOTHAMNION 



Fig. 242. Phaeothamnion confervicola Lag. 



This member of the Chrysophyceae is the 

 only genus in which there is a branched fila- 

 ment. The branches scarcely taper at the 

 ends. The plants are relatively small and 

 grow on the walls of larger filamentous al- 

 gae. Each cell has a parietal, ochre-green to 

 brownish chromatophore. 



Figure 242 



342b Not a branched filament 343 



144 



