PROTOPHYTES. 



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phytes of a grass-green color, growing in fresh water. 

 The cells are generally independent, but in some species 

 remain adherent one to another so as to form a filament. 



FIG. 28. Various species of Staurastrum : A. Staurastrum vestitum. B. Stau- 

 rastrum aculeatum ; C. Staurastrum paradoxum ; D. E. Staurastrum brachiatum. 



Some species have spiny projections of the outer coat, 

 which is of a horny consistence, as in Fig. 28. Others are 

 notched on the sides ; some, as the Closterium, (Fig. 29.) 



FIG. 29. Economy of Closterium lumilci : A. Frond showing central separation at a, 

 in which large globules, , are not seen. B. One extremity enlarged, showing at a the 

 double row of cilia, at b the internal current, and at c the external current. C. External 

 jet produced by pressure on the frond. D. Frond in a state of self-division. 



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