122 OPALINA LESS. 



division (compare Fig. 10, p. 64, with Fig. 23) : the 



FlG. 24. 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 fi'om cyst. 



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



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



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

 chromosomes across its equator (3), the chromosomes pass 



