CILIATA. 



37 



into four, and so on, until a large number of small prominences 

 are formed ; these eventually become free, and constitute the spores. 

 The latter are provided with a flagellum, a pointed process the 

 so-called spine and a nucleus. Their later history has noVbeen 

 followed, and it is not known whether they conjugate. The process 

 of division by which these spores arise is incomplete, and resembles 

 the cleavage of a meroblastic egg. While it is taking place a part 

 of the protoplasm of the rest of the body seems to pass into the 

 dividing disc, but the superficial layer beneath the cuticle always 

 remains. The fate of the maternal body after the separation of 

 the spores is not known. 



Conjugation takes place between two individuals, and results in 

 complete fusion; but the fate of the zygote 

 has not been traced. 



Noctiluca owes its name to its phospho- 

 rescent power. The light is emitted from 

 numerous points in the surface protoplasm, 

 and principally when the animal is disturbed. 

 It sometimes appears in enormous numbers 

 011 the sea surface. It is cosmopolitan, and 

 is principally confined to the coasts, but it 

 has been taken in the open ocean. 



There are two genera both marine. Noctiluca 

 Suriray, with very slight power of change of form ; 

 cosmopolitan. Leptodiscus R. Hertwig, body con- 

 tractile and movements energetic ; Mediterranean. 



SUB-CLASS II. CILIATA.* 



Infusoria provided with cilia ; mouth and 

 anus, nucleus and paranucleus are generally 

 present. 



This group contains the most highly Flo 30 .'_< ?(m , /cMa mytilus 



Organised of the Protozoa. The locomotive (after Stein), seen from ven- 

 .,. -i-i TO -i tral side. Wz ad oral zone of 



appendages are cilia, which are modified in cilia ; c contractile vacuoie ; 

 diverse ways, as will be explained below ; N nucleus ; w paranucleus ; 

 and immovable hairs and stiff bristles, which 



may even have the form of bent hooks and be employed in loco- 

 motion and attachment, are often present. The power of forming 



* 0. Biitschli, loc. cit. "W. Saville Kent, A Manual of the Infusoria. London, 

 1880-82. E. Maupas, " Sur la multiplication des Infusoires Cilies." Arch. 

 Zool exp. et gin. (2), Vol. VI.; and "La Rajeunissement Karyogamique chez 

 les Cilies. Ibid., Vol. VII. 



