PROTOCOCCUS VIRIDIS. 27 



rapidly back and forth propel the naked protoplasm 

 through the water. The motion and form give a 

 strong resemblance to some of the simplest animals, 

 hence the name of animal-like spores. After a time 

 they come to rest, draw in the cilia, secrete a cell-wall, 

 and become ordinary Protococcus cells. Sometimes 

 the protoplasm does not free itself from the cell wall, 

 but contracts somewhat, the cilia are protruded through 

 the wall and the mass propelled as just stated. The 

 production of zoospores at a specified time, as for a 

 class demonstration, is attended with so much uncer- 

 tainty that their study has been omitted from the 

 laboratory work. This method of asexual multiplica- 

 tion will be studied later under more favorable condi- 

 tions in Cystopus. 11 



11 At p. 47- 



