HOW TO KNOW THE FRESH-WATER ALGAE 



7a Cells broadly ovoid or oval in outline, flattened as seen from the 

 side; chloroplasts radiately disposed at the periphery of the cell; 



flagella 2, 1 trailing. Fig. 4. Division Chloromonadophyta 



GONYOSTOMUM 



Figure 4 



Fig. 4. Gonyostomum semen (Ehr.) Stein, 

 showing numerous ovoid chloroplasts 

 and the radiately arranged "stinging" 

 organs. (Normally 1 flagellum is direct- 

 ed forward.) 



This rare swimmer occurs mostly in acid bogs and in shallow lakes, 

 accompanying certain species of Euglena (See Fig. 8). Under the 

 microscope it reminds one of a flat, green bottle; usually is quiet in 

 the microscope fle'd so that its unique internal structure can be studied 

 easily. It has sudden, jerky movements for short distances. 



7b Cells round or oval when seen in both front and side view, some- 

 times slightly flattened, but with flagella directed forward; chloro- 

 plasts not arranged as above; flagella 2, 4, 1 * 8 



8a Cells with numerous, disc-like (rarely ribbon-like chloroplasts); food 

 reserve in the form of variously shaped, colorless or white para- 

 mylum bodies (See Fig. 6) which do not stain blue-black with 

 iodine; slow-moving by a stout flagellum (See Fig. 8); a red eye- 

 spot usually evident Division EUGLENOPHYTA 9 



8b Cells with 1 cup-shaped or star-shaped chloroplast, usually con- 

 taining one or several conspicuous pyrenoids (doughnut-like, shiny 

 bodies buried in the chloroplast or on its surface); food reserve 

 starch, iodine test positive; lens-shaped eye-spot usually evident; 

 actively swimming with fine, often obscure flagella. (See Fig. 13). 

 (Add 5% glycerin to mount to slow down organisms for ob- 

 servation) 12 



*Colorless, one-celled, swimming relatives of Euglena are not included here. Para- 

 menia and Astasia are examples of these strictly protozoan-like genera. Peranema has 

 one stout, rather rigid flagellum extended anteriorly, and a fine, inconspicuous one 

 oppressed close to the cell body. Astasia is highly plastic; swims by one flagellum; 

 has a prominent gullet in the anterior end. 



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