254 EUGLENA CHAP. 



It thus appears that in Euglena nutrition is both 

 holozoic and holophytic (p. 247) : very probably it is 

 mainly holophytic during daylight and holozoic in 

 darkness (compare also p. 256). 



Near the centre or somewhat towards the posterior 

 end is a nucleus (A, nc] with a well-marked " nucleolus " ; 

 at the anterior end is the clear space (r) already referred 

 to, looking very like a contractile vacuole, but which is 

 in reality a non-contractile cavity or reservoir into which 

 the true contractile vacuole (c. v) opens, and which itself 

 communicates with the gullet. 



In close relation with the reservoir is found a little 

 bright red speck composed of pigment granules and 

 called the eye-spot or stigma (st), its colour being due to 

 haematochrome (p. 243). Recent experiments seem to 

 show that it is specially sensitive to light, and is there- 

 fore a true eye in the sense of a light-perceiving organ, 

 although having no actual visual function. 



As in Sphaerella 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 Euglenae. A process of multiple fission 

 (p. 237) has also been described, 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 



