SYNOPSIS OF THE ALGAL PHYLA 



INCE many species and whole divisions of algae are prin- 

 cipally marine in habitat, the following general key or 

 synopsis is given as an aid to a better understanding of 

 the algal groups in fresh-water. 



1 Cells without chloroplasts or chromatophores; pigments blue-green, 

 olive-green, or purplish, distributed throughout the entire protoplast 

 (although cells may be somewhat less colored in the central region); 

 wall usually thin (often showing as a membrane only) and gen- 

 erally with a mucilaginous sheath (wide or narrow, watery or firm 

 and definite); food reserve in the form of glycogen or a starch-like 

 substance; iodine test for starch negative; no motile cells present. 

 Blue-Green Algae CYANOPHYTA 



1 Cells with chloroplasts or with chromatophores, the pigments not 

 distributed throughout the protoplast; cell wall clearly evident (with 

 rare exceptions PyTamimonas. see Fig. 30, e.g.); stored food not in 

 the form of glycogen; iodine test for starch positive or negative ... 2 



2 Cells with grass-green chloroplasts (but see some species of Euglena. 

 see Fig. 8, or the filamentous alga, Trentepohlia, see Fig. 171 which, 

 although possessing chlorophyll, have the green color masked by 

 an abundance of the red pigment, haematochrome) 3 



2 Cells with cholorplasts or chromatophores some other color, gray- 

 green, brown, violet-green, or yellow-green, sometimes purplish... 5 



3 Free-swimming, unicellular; with numerous ovoid, star-shaped, or 

 plate-like chloroplasts which are grass-green; food stored as clearly 

 evident grains of insoluble paramylum (sticks, or plates); iodine 

 test for starch negative; one or two (rarely three) coarse flagella 

 attached at the apex in a gullet; eye-spot or red pigment spot usu- 

 ally evident Euglenoids EUGLENOPHYTA 



3 Organisms not as above * 



4 Unicellular, without an eye-spot; chloroplasts numerous discs usually 

 radially directed at the periphery of the cell; motile by means of 2 

 flagella inserted in an apical reservoir; trichocyst organelles usually 

 present just within the cell wall; food reserve oil 



CHLOROMONADOPHYTA 



4 Unicellular, colonial, or filamentous; swimming or not swimming 

 (although often free-floating); when swimming using 2 to 4 fine 

 flagella attached at the apex of the cell but not in a colorless reser- 



10 



