68 



ZOOLOGY 



SECT. 



springs a single long flagellum (fl.). According to recent observa- 

 tions the flagellum is not a simple thread, but is beset with delicate 

 cilium-like processes. The organism is propelled through the 

 water by the lashing movements of the flagellum, which is always 

 directed forwards ; it can also perform slow worm-like movements 

 of contraction and expansion (A--D), but anything like the free 

 pseudopodial movements which characterise the Rhizopoda is 

 precluded by the presence of a very thin membrane or cuticle which 

 invests the body. Oblique and longitudinal lines ; in the outer 

 layer of the protoplasm may be due to the presence of contractile 

 fibrils. There is a nucleus (nu.) near the centre of the body, and 

 at the anterior end a contractile vacuole (H, c. me.), leading into 



H ft 



f.vac 



FIG. 51. Eugleua viridis. A I), four views illustrating euglenoid movements; E and H, 

 enlarged views ; F, anterior end further enlarged ; G, resting form after binary fission ; c. vac. 

 contractile vacuole in H, reservoir in E and F ; cy. cyst ; ,rf. flagellum ; m. mouth ; nu. nucleus ; 

 ces, gullet ; p. paramylum bodies ; pg. pigment spot ; r. (in H), reservoir. (From Parker's 

 Biology, after Kent and Klebs.) 



a large non-contractile space or reservoir (r.) which discharges into 

 the gullet. 



The greater part of the body is coloured green by the charac- 

 teristic vegetable pigment, chlorophyll, and contains rod-shaped 

 grains of paramylum (H, p.), a carbohydrate allied to starch. In 

 contact with the reservoir is a bright red speck, the stigma (pg.), 

 formed of a pigment allied to chlorophyll and called hcematochrome. 

 It seems probable that the stigma is a light-perceiving organ or 

 rudimentary eye. 



Euglena is nourished like a typical green plant : it decomposes 

 the carbon dioxide dissolved in the water, assimilating the carbon 

 and evolving the oxygen. Nitrogen and other elements it absorbs 

 in the form of mineral salts in solution in the water. But it has 



