PLEUROCOCCUS 67 



mode of propagation by Pleurococcus. Is there any regular 

 order in the number of cells produced ? 



In some unicellular plants similar to Pleurococcus an- 

 other sort of reproduction occurs, viz., by a division within 

 the cell there are formed a number of motile cells called 

 zoospores. These may be of two sizes, the larger ones called 

 macrozobspores, and the smaller ones microzoospores. Lo- 

 comotion of these spores is by means of flagella. Can you 

 suggest any advantage in having a zoospore stage? A 

 conjugation of macrozoospores and microzoospores may 



