98 REPRESENTATIVE PLANTS 



Is this condition more or less complex than the simple cell 

 combinations of pleurococcus ? How might such colonies 

 be useful to animal life? 



Type 5. Spirogyra Species ^ 



« 



Habitat. These plants are the common pond scums, seen 

 in ponds, slow streams, and ditches. They are also com- 

 mon in springs. They are easily grown in the laboratory 

 and in aquaria. 



Appearance. Observe the plant as it grows in the aqua- 

 rium jar. Find out all you can with the unaided eye. 

 What is its color, habit of massing together, and position 

 with reference to the surface? Observe the presence or 

 absence of gas bubbles. With a forceps take up a very 

 small portion and observe the form of the plant as you slowly 

 remove it from the water. Press between thumb and linger 

 and observe the feeling. Compare some standing in the 

 shade with another specimen on which the sun is shining. 

 What do you notice ? 



Study with lens. Take a small portion by means of the 

 forceps, place on a slide, cover with water and a cover 

 glass (a temporary mount), and examine with a lens. What 

 do you find with regard to the form of a separate or single 

 plant OY filament? (Your specimen is probably made up of 

 very many such plants, about the real character of which 

 more will be learned later.) 



Experiment. Take a small portion of the aquarium 

 material, place in a small vial, pour alcohol on it, cork, and 

 set aside. Observe at the end of fifteen minutes. What is 

 the color of the alcohol ? This is the test for chlorophyll. 

 Keep your vial material for future use. 



Structure of filaments and cells. Examine your mount 

 {Ip.) What now do you observe regarding a single thread 



1 There are many kinds. 



