CHAPTER 6 



CILIATES 



Unlike any other large systematic grouping within the protozoa, 

 the Subphylum Ciliophora needs no apology. Exclusion of the 

 opalinids from the subphylum leaves a single, almost certainly 

 monophyletic class of ciliated organisms with differentiated macro- 

 and micro-nuclei and no detectable centrioles. Problems of 

 phylogeny within the group are far from being solved, but there 

 are sufficient clues to make speculation on the subject an absorbing 

 and rewarding game, and one to which electron microscopy should 

 ultimately contribute in large measure. Already, ciliates have 

 attracted a large number of investigations into their ultra- 

 structure — because there is so much of it. Even so, the results 

 constitute a random scattering of data which at present writing 

 still defy systematic analysis. The very great degree of morpho- 

 logical specialization, particularly at the surfaces, of ciliate cells 

 means that a thorough study of a single species requires a tremen- 

 dous investment of time. That such investments on an increasingly 

 wider scale will pay off is not to be questioned; the structural 

 specializations of ciliates are answers to common problems of cell 

 function and development. 



Since Volume II of Grasse's Traite de Zoo/ogze, slated to include 

 a coverage of the ciliates by Faure-Fremiet, has not reached 

 publication, the taxonomic arrangement to be followed here will 

 be that of Corliss (1956, 1959a, 1961) whose work has been 

 strongly influenced by Faure-Fremiet (see for example the latter's 

 brief outline of ciliate systematics in 1950). Terminology for 

 ciliate body parts and organelles will be used as defined by 

 Corliss (1959a). 



The most striking morphological feature of ciliates is the infra- 

 ciliature, consisting primarily of kinetosomes — whether or not 

 they bear cilia — in characteristic topographic array. In primitive 

 and many embryonic forms kinetosomes are aligned in meridional 



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