ETE-SPOT IN EUGLENA YIBrDig. 463 



On the Eye-spot and Flagellum in ISuglena viridis. 

 By Harold Wager, P.L.S. 



[Read 2nd Novembsr, 1899.] 

 (Plate 32.) 



EuGLUJSFA viRiBis IS commonly found in stagnant water whicli 

 contains a considerable amount of organic matter. It is often 

 found abundantly in the liquid which runs from manure heaps, 

 forming at certain periods a dense greeu scum on its surface. 

 It is found sometimes in water troughs, and on mud in roadside 

 gutters ill places where refuse water from houses is thrown; 

 and it is often very abundant on sewage farms. 



Under ordinary conditions it is a free swimming organism, 

 capable of moving very rapidly through the water by means of a 

 cilium, or flagellum, which is placed at the anterior end of the 

 body; but it can exist for a long time in a non-motile condi- 

 tion in an encysted state, surrounded and protected by a very 

 thick cell-membrane. It is, however, capable of passing again 

 into the motile condition as soon as the environuient becomes 

 favourable. 



General Structure. . . ■ 



An excellent account of the general structure and life-history 

 of the genus Euglena is given by Klebs *, whose memoir records 

 the literature on the subject up to the date of its publication. 

 A large amount of information concerning tlie structure of the 

 various species of Euglena and allied genera is given by Stein t, 

 Biitschli %, Saville Kent § ; and, more recently, a good general 

 account of the group will be found in the first volume of the 



* " Ueber die Organisation eiiiiger Flagellaten-Gruppen undihre Beziehimgen 

 zu Algen und Infusorien." Unters, aus deiii bot. Inst, zu Tiibingen, Bd. I., 

 1881-86. 



t Der Organismus der Infusionsthiere, III. Der Organismus der Flagellaten. 

 Leipzig, 1878. 



\ Bronn's Classen und Ordaungen des Tliierreiclig, I. Protozoa, 1883-87. 



§ A Manual of the Infusoria. London, 1880-82. 



