-254 EUGLENA CHAP. 



a nucleus (E, mi) with a well-marked nucleolus, and at the 

 anterior end is a clear space (c. vac), looking very like a 

 contractile vacuole. It has been shown, however, that this 

 space is in reality a non-contractile cavity or reservoir (H, r) 

 into which the true contractile vacuole (c. vac) opens, and 

 which itself discharges into the gullet. 



In close relation with the reservoir is found a little bright 

 red speck (pg\ called the pigment spot or stigma. It con- 

 sists of haematochrome (p. 243), and is curiously like an 

 eye in appearance, so much so that it is often known as the 

 eye-spot. Recent experiments seem to show that it is 

 specially sensitive to light, and is therefore a true eye in the 

 sense of a light-perceiving organ, although having no actual 

 visual function. 



As in Sphserella a resting condition alternates with the 

 motile phase : the organism loses its flagellum and surrounds 

 itself with a cyst of cellulose (G, cy, see p. 244), from 

 which, after a period of rest, it emerges to resume active life. 



Reproduction takes place by simple binary fission of the 

 resting form, the plane of division being always longitudinal 

 (G). Sometimes each product of division or daughter-cell 

 divides again : finally the two, or four, or sometimes even 

 eight daughter-cells emerge from the cyst as active Euglense. 

 A process of multiple fission (p. 237) has also been de- 

 scribed, numerous, simple, minute, active bodies or spores 

 being produced, which gradually assume the ordinary form 

 and size. 



We have seen that typical animal-cells, such as those of 

 the frog (Part I, Chap. VII) are not provided with a 

 cellulose cell-wall and do not contain chlorophyll. It is 

 characteristic, on the other hand, of most plant-cells which 



