STONEWORTS 



333 



Green Algae because they are green, while others regard them as 

 so different from any of the Algae as to put them in a separate 

 class. They grow in fresh and brackish waters and often form 

 dense masses of vegetation covering large areas. They grow 



FIG. 287. Char a fragilis. A, part of a plant, showing nodes, internodes, 

 and the two kinds of branches (natural size) ; B, part of a plant, showing a 

 node bearing sex organs, the oogonium enclosed in its jacket being at o and 

 the antheridium with its shield-shaped wall cells shown at a (X 25); C, wall 

 cell of the antheridium, showing the stalk-like projection at the end of which 

 are borne the filaments in the cells of which the sperms are produced (X 

 about 50) ; at the left of C, two cells of a filament in which the sperms are 

 formed, and a single sperm below. Redrawn from Sachs and Thuret. 



attached to the bottom and are often so incrusted with calcium 

 carbonate that they are rough and brittle as the name Stoneworts 

 suggests. 



The plant body has a much branched stem-like axis quite 

 distinctly differentiated into nodes and internodes (Fig. 287). 



