108 



PLANTS, THE FOOD OF ANIMALS 



gether in groups of two, three or more cells, sometimes eight or 

 nine forming a loosely arranged colony. The union is only 



FIG. 41. Sphaerella lacustris. Various stages in vegetative life and spore for- 

 mation. A, a typical red-colored, resting cell; B, a red individual with two 

 flagella and a yellow-green border of chlorophyll; C, an older individual with 

 more chlorophyll and a widely-distended cell- wall; D, a mature green individual 

 with red eye-spot; , individual that has lost its flagella and developed a thick 

 cell- wall; F, 16 microzooids formed in the mother-cell; G, mature megazooid; 

 H, 7, megazooid formation. (From Hazen.) 



temporary, however, for ultimately the cells separate and live 

 as independent units (Fig. 40). 



