GEEEN FELT 269 



c. Color. — What is it ? Is it evenly or unevenly dis- 

 tributed? To what is it due? Is it darker or 

 lighter than Spirogyra ? "Why ? 



d. Structure. — Is the filament composed of cells? 

 How many ? How are the cells situated with 

 regard to one another? Compare with Spiro- 

 gyra. Can you distinguish cell-wall, vacuole, nu- 

 cleus, starch grains, pyrenoids, etc. ? Do you 

 find chromatophores, as chlorophyll bodies ? 

 What is their shape ? Arrangement ? How do 

 they compare in size, color, arrangement, shape, 

 etc., with those of Srpirogyra\ Look for chloro- 

 phyll bodies in the process of division. Plasmo- 

 lyze the filament with two per cent, solution of 

 salt or sugar in water, and examine the primor- 

 dial utricle. Does the cell-wall show any pro- 

 tuberances, stratification, or openings ? What is 

 its color? Look for spherical, glistening oil- 

 di'ops in old filaments. Is the surface of the fila- 

 ment of this plant as clean and free from other 

 organisms as is Spirogyra ? Does Vaucheria have 

 the characteristic mucous coating of Spirogyra ? 

 What is there about Vaucheria which enables it 

 to form a " felt " ? Why cannot Sjpirogyra do the 

 same? 



Make drawings illustrating all of the structures ex- 

 amined. 



B. — Reproductive Condition. 



Can you identify the reproductive stage with- 

 out making a microscopic examination '? How ? 

 Find some plants bearing sexual organs, which 

 may be distinguished as short outgrowths from 

 the side of the filament. 



