28 GENERAL BIOLOGY. 



smaller, green form, Pleurococcus. See 

 below.) 

 Sketch (X 6). 



3. Look for cells whose contents are undergoing 



endogenous division. Sketch. 



4. Treat with iodine. What structures show 



more clearly? 



5. Crush the cells by pressure on the cover-glass. 



Note the unstained cell-walls, and the cell- 

 contents stained brownish yellow with iodine 

 (showing the presence of protoplasm). 

 B. MOTILE STAGE : Zoospores. 



(These develop from forms in the resting stage 

 that have been in water for a number of hours.) 

 Study tvith a high power. Observe : 

 I. Larger motile forms : macrozoospores. 



1. Form : pear-shaped. 



2. Color. 



3. Structure. 



(a) Thin colorless cell-wall. 



(b) Central protoplasmic mass separated from 



cell-wall by clear space. Through the 

 clear space delicate protoplasmic threads 

 extend from the central mass to the 

 inner surface of the cell-wall (probably 

 to a thin layer of protoplasm lining 

 the cell-wall). 



From the colorless apex of the proto- 

 plasm two processes pass to the pointed 



