38 COMMON POND SCUM. 



e. The rounded, usually much brighter body im- 

 bedded in the nucleus, and occupying a consid- 

 erable part of it, the nucleolus. 



f. Draw one or more cells showing all parts noticed. 



6. The turgidity of the cells, shown by the considerable 

 convexity of the last end wall of a broken filament, 

 which is repeated in lessening degree by the walls of 

 successive cells until a point is reached where the pres- 

 sure on opposite sides is equal, and the wall remains 

 plane. Illustrate with a sketch. 



C. THE FRUITING PLANT. Under low power, notice 



1. The filaments lying side by side in pairs, held together 

 by conjugating tubes. 



2. The irregular outline of the filaments, caused by the 

 uneven lateral expansion. 



3. The varying character of the contents of the cells : some 

 with distinct bands of chlorophyll ; some with a con- 

 fused green mass ; some with green or brown rounded 

 bodies of definite shape, the zygospores ; some empty. 



Under high power, notice 



4. The general shape of the cells as influenced by the cell 

 contents. 



5. The conjugating tube : note 



a. The enlargement at the middle, where an indenta- 

 tion marks the line of union of the two originally 

 separate portions. 



b. In some cells which have not yet conjugated, a 

 greater or less protuberance on the side next the 

 accompanying filament ; the beginning of a con- 

 jugating tube. 



6. The cell contents. 



