SPIROGYRA. 39 



The vegetative condition may be found at any time 

 during the warmer portion of the year. The reproduc- 

 tive condition occurs from early spring to June and 

 July, and sparingly during the remainder of the warm 

 season. The species usually grow intermixed, and 

 almost any species gathered will answer for the present 

 study, though one with a small number of loose spirals 

 is best. 



LABORATORY WORK. 



GROSS STRUCTURE. 



Taking fresh specimens in a white dish, observe: 



1. The vivid but yellow-green color as seen in the mass. 



2. The slippery feel when the plant is taken between the 

 fingers. 



3. The fine unbranched filaments of which it is composed. 



4. The uniform diameter. 



5. Their length. 



Place some in alcohol and after some time notice: 



6. The color imparted to the alcohol by the chlorophyll. 



MINUTE STRUCTURES. 



I. VEGETATIVE CHARACTERS. 



Under low power observe: 



1. The length; if traced to the end, the filament will probably 

 be found broken. 



2. The uniform diameter. 



3. The cell contents; colorless, except the conspicuous green 

 chlorophyll bands. 



Using a high power observe: 



1. The shape of the cells. 



2. Their relative length and breadth. 



