THE GREEN ALG^ (CHLOROPHYCE^) 195 



extensively branched (Fig. 158). When growing vigorously, 

 new branches are constantly being formed at the upper ends of 

 some of the segments. Each 

 segment appears to be one 

 cell, though really a good 

 many nuclei with their ac- 

 companying masses of cyto- 

 plasm are contained within 

 each wall. Such a structure is 

 called a coenocyte, and though 

 this same condition is found 

 in another plant that we shall 

 study (Vaucheria, Sect. 183), 

 it is not common in the plant 

 kingdom. For our purpose 

 we may think of 

 each segment of 

 Cladophora as like 

 one cell. All of 

 these branching 

 segments may to- 

 gether compose 

 a plant of great 

 size as compared 

 with the smaller 

 dimensions of a 

 Nbstoc, an Oscil- 

 latoria, a Pleuro- 

 coccus, or even a 

 Spirogyra. 



In each seg- 

 ment there are 



FIG. 158. Branching of Cladophora 

 many small cnlo- 



_ J After Collins 



roplasts, crowded 



together so closely as to present an almost solid green color 



even when viewed under considerable magnification. 



