APPENDIX II. 



DIRECTIONS FOR COLLECTING AND 

 PRESERVING MATERIAL. 



Those who cannot collect the plants they require can order them from the Cambridge 

 Botanical Supply Co., 1286 Massachusetts av., Cambridge, Mass. Orders should be 

 placed in advance of the collecting season to insure obtaining the material. 



Pleurococcus. For this and similar one-celled algae, collect pieces 

 of shaded fence boards near the ground, or flakes of bark from 

 the north side of trees in groves and parks, which show a bright 

 yellow-green color. These may be preserved dry. 



Oscillaria. Search in drippings about watering troughs, city 

 gutters where water stands, or any open drain which contains 

 organic matter decaying in stagnant water. A glass jar or 

 aquarium in which water plants have decayed will usually con- 

 tain this plant. It may be recognized by its bluish or blackish 

 green color, and often occurs in coherent films or thicker masses. 

 It may be obtained fresh at any time of year, either out doors or 

 in the laboratory. 



Rivularia. Collect in midsummer or later the larger water 

 plants to whose leaves and stems adhere jelly-like lumps of a 

 dirty green color, from the size of a pinhead to 1-2 cm. in 

 diameter. The margins of lakes, pools, and slow streams furnish 

 the best localities. 



Nostoc colonies form similar jelly masses, commonly larger and 

 free floating or attached. Preserve both like the following. 



Spirogyra or Zygnema. Search in spring or early summer in slow 

 streams fed by springs. It will be recognized when in vegetative 

 condition by rich green color and slippery " feel." Under the 

 microscope the form of the chloroplasts will show the genus. 



401 



