OSCILLATORIA. 25 



LABORATORY WORK. 

 GROSS STRUCTURE. 



1. Examine a small mass of the living plant that has been 

 allowed to remain undisturbed for several hours in a 

 watch-glass of water. Observe: 



a. The deep blue-green color. 



b. The hair-like unbranched filaments, radiating from the 

 central mass. 



2. Sketch the plants as they appear in the watch-glass. 

 Pulverize a mass of the plant that has been thoroughly 



dried, place in a test-tube or vial with nearly twice the bulk 

 of water, and after ten to twenty-four hours observe: 



3. The color of the solution when seen by transmitted light, 

 and the very different color by reflected light. 



Pour off the supernatant water, add the same amount of 

 alcohol, and after an hour or more observe: 



4. The yellow-green color imparted by the chlorophyll. 



MINUTE STRUCTURE. 



I. GENERAL CHARACTERISTICS. 

 Under low power observe : 



1. The color. 



2. The numerous filaments of uniform diameter, destitute of 

 branches. 



3. Study the movements. 



II. THE INDIVIDUAL FILAMENT. 

 Under high power observe: 



i. The structure in detail, as follows: 



a. The rounded extremities of uninjured filaments. 



b. The outline of an uninjured apex, whether attenuated 

 or not, and whether bent to one side or straight. 



