I2O 



OPALINA 



chromatin breaks up (c, 2), a spindle is formed with the 

 chromatin across its equator (3), the chromatin passes to the 



FIG. 25. Opalina ranarum. 



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 nuclear division. 



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 cyst. 



K, the same after multiplication of the nucleus has begun. 



(A c, after Pfitzner ; D K, from Saville Kent after Zeller.) 



poles of the spindle (4, 5), and the nucleus becomes con- 

 stricted (5), and finally divides into two (6). 



