180 



UNICELLULAR PLANTS. 





FIG. 92. Protococcus (Pleurococcus) from the bark of an elm tree, in active vegeta- 

 tion and showing aggregation into masses of cells. A, Pleurococcun in the dried 

 condition. B, An&wtccw (?), showing endogenous division into two cells and (C) 

 into four. D, E, F, motile forms of Protocorciw (after Cohn). 



