CILIOPHORA 



8l 



further subdivided by the arrangement of the ciha. Opalina has a 

 number of nuclei which are all alike, but it is claimed that each 

 contains two sets of chromosomes (p. 688), one representing the 

 micronucleus of other species, and one the meganucleus. Opalina, 

 does not, however, undergo the typical ciliate conjugation, which 

 we have seen in Paramecium and Vorticella. The cilia of Ciliata 



Fig. 48. — A suctorian (Podophrya) feeding on the ciliate Colpidium — 

 From Kitching, /. exp. Biol., 1952, 29, 255. 



have a similar structure to those of Metazoa (p. 503), but can 

 reverse their direction of beat, which those of Metazoa other 

 than coelenterates never do. 



On account of the difference in the nuclei some protozoologists 

 feel that the Ciliophora should be raised to the rank of a sub- 

 phylum, to which the name Heterokaryota has been given. 

 When this is done the other three classes may be united as 

 Subphylum Homokaryota. 



