44 



SYSTEMATIC ZOOLOGY 







FlG. 26. Noctiluca miliar is. Spore formation. (After 

 Robin, from Calkins' Protozoa.) 



property of emitting light at night and is one of the animals 

 which produce the phosphorescence of the ocean. Reproduc- 

 tion takes place by sim- 

 ple division and also by 

 spore formation; in the 

 latter case the proto- 

 plasm collects about the 

 nucleus, which divides 

 many times, and a mass 

 of budlike spores is 

 formed, projecting above 

 the surface (Fig. 26). 

 These spores then be- 

 come free and swim 

 about by means of a 

 flagellum. This process 

 of spore formation may 

 or may not be preceded 

 by a temporary union 

 of two individuals, that is, by conjugation. 



Leptodiscus (Fig. 25) is two or three times as broad as Nocti- 

 luca, and has a similar structure except that the tentacle is absent, 

 and the general form of the body is like a watch crystal or a 

 meniscus. 



CLASS IV. CILIATA 



The Ciliata (Lat. cilium, an eyelash) are often known as the 

 Infusoria (Lat. infusorium) because some species are particu- 

 larly abundant in certain infusions ; the term Infusoria is also 

 used at times to include both the Mastigophora and the Ciliata. 

 The Ciliata are the most highlv differentiated of all the Pro- 

 tozoa, and are distinguished from the other classes by the 

 presence of numerous, delicate processes, hairlike and motile, 

 the cilia, which are always present during some part of the life 

 of the individual ; they serve both tor locomotion and for 

 procuring food. These animals occur for the most part in 

 fresh water, though some are marine. They are found in great 

 abundance in stagnant pools and are generally free-swimming 

 individuals, although not a few are attached to plants and other 



