PHYLUM PROTOZOA 



4' 



transverse groove which completely encircles the body ; the 

 former alone acts as an organ of locomotion, the latter lies 

 habitually in the groove and performs undulating move- 

 ments. Noctiluca (Cystofiagellata) (Fig. 16), which is the 

 largest member of the class, being about half a millimetre 

 in diameter, has two flagella, one of which is modified in 

 a remarkable manner. The body of Noctiluca is globular, 

 with a cleft along one side so that it resembles a miniature 

 peach. From this springs a very large and stout flagellum 



■ f 



Fig. 16. — Noctiluca miliaas. a, the adult animal; 6, c, flagellulae; ^-.tentacle; 

 f, flagellum; in, mouth; n, nucleus. (From Lang, after Butschli.) 



or tentacle, which is marked with a number of transverse 

 lines or striations ; and a second flagellum, of comparatively 

 small size, lies in the gullet. 



Though all the Mastigophora are characterised by the 

 possession of flagella, there are a few, such as Mastigamozba 

 (Fig. 13, 4), which also possess pseudopodia, and may be 

 capable of amoeboid movements. 



Nutrition is effected in a variety of different ways. Some 

 forms live in decaying organic infusions, not taking in solid 

 food-particles, but absorbing nourishing matter in a dis- 



