122 



Aquatic Organisms 



mud after the water has receded, dotting the surface 

 thickly, as with greenish beads of dew. 



The water net and its allies — The water net {Hydro- 

 dictyon) wherever found, is sure to attract attention by 

 its curious form. It is a cyhndric sheet of lace-like 

 tissue, composed of slender green cells that meet at 



Fig. 43. A rather irregular portion of a siieet of water net 

 (Hydrodictyon) 



their ends, usually by threes, forming hexagonal meshes 

 like bobbinet (fig. 43). Such colonies may be as broad 

 as one's hand, or microscopic, or of any intermediate 

 size; for curiously enough, cell division and ceU 

 growth are segregated in time. New colonies are 

 formed by repeated division of the contents of single 



