4 o 4 



THE INFUSORIA 



Family OPALININA, Stein. Without a mouth. Anoplophrya, Stein. 

 Oval to elongated in shape, slightly twisted on its axis. A row of contractile 

 vacuoles along one border. 0'9. Digestive canal of Annelids and Gas- 

 tropods, and in the blood of some Crustacea. (Fig. 30.) Hoplitophrya, 

 Stein. Anterior end of the body formed like a sucker and provided with 

 two hooks. A long tubular contractile vacuole. 0'9. Intestine of 

 Planarians and Oligochaeta. Discophrya, Stein. A large sucker- like 



Fio. 54. 



Reproduction of Opcdina ranarum. 5, a 

 specimen in process of binary fission ; 6, the 

 same ; the process of fission has now reduced 

 the individuals to a relatively small size ; 7, 

 smallest flssion produced fragment encysted, 

 expelled from the frog in this state and 

 swallowed by a tadpole ; 8, young uninucle- 

 ate individual which has emerged from the 

 cyst within the tadpole and will now multi- 

 ply its nuclei and grow to full size. (After 

 Zeller.) 



a 



Fio. 55. 



rinopsis sepiolae, Foett, a mouthless 

 ichan from the liver of the squid. 

 o, a, fragments of the meganucleus which 

 in the younger stages is a continuous rod 

 or band, b, b, non-contractile vacuoles. 

 X 100. 



anterior end without hooks. 2 mm. Digestive canal of Planaria and 

 Amphibia. Opalina, Purkinje (Figs. 25, 53, 54). The most aberrant of 

 all the Hymenostomata. No contractive vacuoles. Numerous mega- 

 nuclei. 0*1. Rectum and occasionally the bladder of several Anura. 

 Opalinopsis, Foettinger (Fig. 55). Elongated in form, with a swollen 

 anterior end. In the young forms a band-like meganucleus, which later 

 breaks up into a large number of irregular fragments. 1'5. Liver and 

 venous appendages of various Cephalopoda, 



