HOW TO KNOW THE FRESH-WATER ALGAE 



43a (41) Colony balloon-like or pear-shaped, narrowed at base to form 

 a stalk-like attachment; pseudocilia usually visible. Fig. 37.... 



APIOOYSTIS 



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'b 00 od °° 

 ",8 % °V 



o o'a-" 



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" °o °„ o oo °°* 



,MDO 



00 - o 



oo- . 





;*. 



°. 



S 



j'oO 00 9j> „" "*<4 



:■/» ooo o cb 



>°° o 



o oo Op.. 



e% a *■> «. w i 



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Fig. 37. Apiocystis Brauniana Naeg. Dia- 

 gram of a colony showing cell arrange- 

 ment and pseudocilia. 



This plant is always in the form of a micro- 

 scopic thallus growing attached to filamentous 

 algae or to stems of aguatic plants. The 

 cells are arranged somewhat irregularly in 

 four's and under favorable conditions show 

 pseudocilia like Tetiaspoia. (Fig. 35.) 



Figure 37 



43b Colony some other shape; pseudocilia absent 44 



44a Colonial mucilage forming a fusiform shaped envelope; cells simi- 

 larly shaped as the envelope, with long axes more or less parallel. 

 Fig. 38 ELAKATOTHRIX 



Fig. 38. 

 Printz. 



Elakatothrix viridis (Snow) 



Somewhat 'cigar'-shaped cells placed 

 end to end in pairs within a fusiform, 

 gelatinous sheath. E. gelatinosa Wille 

 has both ends of the cell pointed where- 

 as other species have the adjoined 

 ,Qure poles truncate. In one of the three 



species found in this country, Elakatothrix americana Wille, the gela- 

 tinous colonial sheath is irregularly lacy or fringed. 



44b Colonial mucilage not fusiform 45 



39 



