CCENOBlEjE 



297 



protoplasm again breaks up into zoospores, which swarm about for twenty 

 or forty minutes within a sac which protrudes out of the protoplasm. 

 When they come to rest, they arrange themselves within the sac into a 

 small net consisting of from 200 to 300 cells, which gradually grows to 



FIG. 260. Hydrodictycn ntricu?atum Roth. A, net (natural size). B, mesh (x 10), C, megazoo 

 sporange (x 300). D, megazoospores (x 600). , gametange with zocgametes(x 300). (After 

 Cohn.) 



one of the ordinary size. In some of the polyhedra smaller and more 

 numerous microzoospores are formed ; but they also appear to unite 

 again into a net without displaying sexual functions. 



LITERATURE. 



Nageli Gattungen einzelliger Algen, 1849, p. 92. 



Braun Verjiingung in der Natur, 1851 (Ray Soc. , Bot. and Phys. Mem., 1853) ; and 



Algoe unicellulares, 1855. 

 Pringsheim Monber. Berl. Akad., 1860, p. 775 (Quart. Journ. Micr.'Sc., 1862, pp. 



54 and 104). 



