HOW AND WHERE TO COLLECT FRESH-WATER 



ALGAE 



ILAMENTOUS algae can be collected from mass growths 

 by hand, of course, and representative tufts placed in vials 

 or collecting jars. Less conspicuous forms may be found 

 as fuzzy films on submerged grasses, old rush culms, and 

 sticks. Using the fingers these growths can be lifted away 

 or pulled from their attachment, or short sections of stems of aquatic 

 plants and grass leaves can be placed in vials and the algae removed 

 with scraping tools in the laboratory. A dropping pipette and a pair 

 of tweezers are useful for collecting minute forms. 



Using the back of the thumb nail, or a dull-edged knife will serve, 

 greenish coatings on rocks and submerged wood can be scraped away. 

 Such an instrument is useful for removing samples of green or brown 

 felt-like or mucilaginous growths from wet stones about waterfalls, 

 from dripping cliffs and rocky outcrops. 



Submerged glass, shells, and bits of crockery in the water furnish 

 substrates for many algae which occur as inconspicuous green discs 

 or tufts. Old, rotting wood may be perforated with algae which lie so 

 far below the surface that they are scarcely visible, but wood that 

 appears at all greenish from the exterior should be examined. 



Feel under the rim of dams or along the edges of stones in flowing 

 water. Many blue-green and also some of the more rare freshwater 

 red algae occur in such habitats. 



On and in damp soil are to be found numerous species of Cyano- 

 phyta and diatoms. Sometimes algae occur in pure strands' and sheets 

 or films of a single species may be lifted or scraped from soil, wet 

 boards, and the face of moist cliffs. 



On beaches near the water line, but back far enough where the 

 sand lies unmolested most of the time, the upper dry layer of sand 

 may be removed to disclose a densely green stratum of algae. The 

 green sand can be scraped into a container and rinsed, and then when 

 the water is poured off in the laboratory an interesting mixture of 

 algae will be found, together with a variety of microscopic animals 

 (protozoa, rotifers, copepods, etc.). This biotic cosmos is known as 

 psammon and includes many organisms that normally occur in sandy 

 beaches although not in the open water of a nearby lake or stream. 



In Nitella (one of the large green algae), in Lemna trisulca (one of 

 the duckweeds), in Bicciocarpus natans (a floating liverwort) occur vari- 

 ous green and blue-green endophytic algae. Small portions of these 



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