96 



REPRESENTATIVE PLANTS 



Structure. Examine with the (Ip) or with the (hp), 

 according to the kind furnished, using as before a tem- 

 porary mount. How do the cells compare in shape with 

 those of nostoc? Are they more or less loosely attached to 

 each other ? How could you make a filament like oscilla- 

 toria from a nostoc necklace ? What shape have the free 

 ends of the filament? How do you explain? (Think of a 

 hollow rubber ball.) Observe the color and other features. 



Drawings. Make sketches showing all the features dis- 

 covered. 



Comparison of the algae. Compare pleurococcus, nostoc, 

 and oscillatoria, with reference to the arrangement of cells. 

 Observe the change from single cell to filament. 



Table. Record the comparison in a table thus : — 



Cell 

 Arrangemeni 



The blue green algae. 1. Blue green algae (nostoc, oscilla- 

 toria, and many others) have some relationship in structure 

 and habits to fungi (studied later) and are often found in 

 water-supply reservoirs. Discover their importance in such 

 places and the methods necessary for their removal. (Con- 

 sult for this purpose good reference books.) 



2. These algse are by some phiced in a group with the 

 bacteria (to be studied later), called the fission plants, be- 

 cause of their method of reproduction. 



Conclusion. Keep in mind all these forms. What really 



