250 M. M. Mercaur 
a type of mitosis that resembles that of the multinucleated species 
much more than that of O. idtestinalis and O. caudata (‘Text Fig. V, 
a—f). The resting nucleus is like that of the multinuclear species; 
the chromosomes are numerous and are linear. In his Text Fig. XV 
(my Text Fig. V), @ shows superficial chromatin masses like those in 
Text Fig. V, Brzzensercer’s figures of mitosis. a—f in O. macronucleata; g—l in 
O. lanceolata: a resting nucleus; b—f stages in division: a—f * 2000 diameters; 
g—l X 850 diameters. 
a resting nucleus of O. ranarum; b shows the chromatin net without 
such larger masses; ¢ is a spireme stage with the chromatin thread 
apparently ready to fragment to form the many chromosomes; 
d, e and f show anaphases. BrzzenBERGER gives also five figures 
of nuclei of O. lanceolata, whose mitosis seems to resemble somewhat 
that of O. saturnalis (Text Fig. V, g—l). 
Enlarged individuals of Opalina caudata and of other species. 
In both species of Bombinator one finds frequently, especially 
in the spring, certain very thick individuals of O. caudata (Fig. 88, 
