270 



OPALINA 



presents a condition of things intermediate between the 

 unicellular and the multicellular types of structure. 



P'lG. 71. — Opalina ranaium. 



A, living specimen, surface view, showing longitudinal rows of cilia. 



B, the same, stained, showing numerous nuclei {nu) in various stages of division. 



C, I — 6, stages in the division of a nucleus, 



D, longitudinal fission. 



E, transverse fission. 



F, the same in a specimen reduced in size by repeated division. 



G, final product of successive divisions. 

 H, encysted form. 



I, uninucleate form produced from CA,-st. 



K, the same after multiplication of the nucleus has begun. {From Parker's Biology : 

 A— C, after Pfit;:ner ; D— K. from Saville Kent, after Zeller.) 



There is no contractile vacuole, and no trace of either 

 mouth or gullet, so that the ingestion of solid food is impos- 

 sible. The creature lives, as already stated, in the intestine 



