THE OPALINID CILIATE INFUSOEIANS. 



39 



to divide by fission. In the ordinary individuals each nucleus shows 

 a group of chromatin masses of varying number, lying peripherally 



FIG. 16.— Protoopalina pelobatidis ; a to e, individuals in the usual condition; 



/, AN individual IN TRANSVERSE FISSION, WITH ANAPHASE NUCLEI ; Q, LONGITUDINAL FIS- 

 SION. (NOTE 8 MACROCHROMOSOMES. THESE ARE OMITTED IN ONE END OF ONE NUCLEUS 

 WHICH WAS OVERLAID BY DftBRIS) ; h, A CYST; a TO f, MAGNIFIED 460 DIAMETERS ; <7 AND h 

 MAGNIFIED 2,000 DIAMETERS ; a TO f HAVE THE ANTERIOR END TOWARD THE TOP OF THH 

 PAGE ; IN g THE ALREADY DOUBLE ANTERIOR END IS TOWARD THE RIGHT. 



about in the equator of the nucleus (fig. IC, a and c). The nuclei in 

 this condition may be rather wide, but are more often more slender. 

 In general they are noticeably more slender than in P. intestinalis. 



