EUGLENOIDINA 297 



numerous haematochrome granules, 0.3-0.5/x in diameter: ovoid 

 paramylon bodies; reproductive and temporary cysts and protective 

 cysts, 34-47^ in diameter, with a gelatinous envelope. 



Johnson (1939) found that the color of this Euglena was red in 

 the morning and dull green in the late afternoon, due to the dif- 

 ference in the distribution of haematochrome within the body. 

 When haematochrome granules are distributed throughout the 

 body, the organism is bright-red, but when they are condensed 

 in the center of the body, the organism is dull green. When part 

 of the area of the pond was shaded with a board early in the 

 morning, shortly after sunrise all the scum became red except 

 the shaded area. When the board was removed, the red color 

 appeared in 11 minutes while the temperature of the water remained 

 21°C. In the evening the change was reversed. Johnson and Jahn 

 (1942) later found that green-red color change could be induced by 

 raising the temperature of the water to 30-40°C. and by irradiation 

 with infrared rays or visible light. The two workers hold that the 

 function of haematochrome may be protective, since it migrates to a 

 position which shields the chromatophores from very bright light. 

 If this is true, it is easy to find the species thriving in hot weather in 

 shallow ponds where temperature of the water rises to 35-45°C. In 

 colder weather, it is supposed that this Euglena is less abundant and 

 it exists in a green phase, containing a few haematochrome granules. 



Genus Khawkinea Jahn and McKibben. Similar to Genus Eu- 

 glena, but without chromatophores and thus permanently colorless ; 

 fresh water. 



K. halli.L and M. 30-65/z by 12-14/*; fusiform; pellicle spirally 

 striated; plastic; flagellum slightly longer than body; stigma 2-3/x in 

 diameter, yellow-orange to reddish-orange, composed of many gran- 

 ules; numerous (25-100) paramylon bodies elliptical or polyhedral: 

 cysts 20-30^ in diameter; putrid leaf infusion; saprozoic (Jahn and 

 McKibben, 1937). 



K. ocellata (Khawkine). Similar to above; flagellum 1.5-2 times 

 body length; fresh water. 



Genus Phacus Dujardin. Highly flattened; asymmetrical; pellicle 

 firm; body form constant; prominent longitudinal or oblique stria- 

 tion; flagellum and a stigma; chromatophores without pyrenoid 

 (Pringsheim) are discoid and green; holophytic ; fresh water. Numer- 

 ous species (Skvortzov, 1937; Pochmann, 1942; Conrad, 1943; Alle- 

 gre and Jahn, 1943); Morphology and cytology (Krichenbauer, 1937; 

 Conrad, 1943). 



P. pleuronectes (Miiller) (Fig. 119, a). 45-100 n by 30-70/x; short 



