6o 



CILIATE PROTOZOA 



CILIATES OF THE FROG 



The rectum of the frog contains an interesting population of 

 ciUates. which hve chiefly in the hghter-coloured contents of its 



an., Anus 



Pig. 32. — Ciliata from the rectum of the frog. 



A Ot>alina ranarum ; B, Balantidium mtozoon ; C, Nyctotherus cordiformis. 

 ; C.V.. contractile vacuoles ; ec, ectoplasm ; en., endoplasm ; g., gullet ; meg., meganucleus ; 



mi., micronucleus ; nu., nuclei ; pst., peristome. 



Fig. 33. — Opalina ranarum. 



A , Ordinary individual in longitudinal fission ; B, the same in transverse fission ; C, small encysted 

 individual (distributive phase) ; D, gamete ; E, encysted zygote. 



foremost region (Figs. 32, 33). Balantidium entozoon differs 

 from B. coli (p. 77) in having four contractile vacuoles and a 

 longer peristome. Nyctotherus cordiformis resembles the Balantidia 

 in its general features, but is bean-shaped, with a long gullet 

 placed in the middle of the hollow side, an undulating membrane, 

 one contractile vacuole in the hinder part of the body, and a 

 remarkable permanent anus, lined with ectoplasm, at the hind 

 end. 



