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 " ; 1 

 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) t 

 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- 2 37) nas ^so 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 



