248 M. M. Mercaur 
number of the chromosomes is six instead of eight (Fig. 81, 82, 
Pl. XX). In the multinucleated species the nuclei are much smaller 
and Jess favorable for study and I have given them much less 
attention. The nuclear membrane persists through the whole mi- 
tosis; there are no indications of centrosomes; the spindle is similar 
to that of O. intestinalis; the chromatin lies just beneath the nuclear 
membrane. 
The number of the chromosomes in 0. ranarum and O. dimidiata, 
aS NERESHEIMER has said, seems to be twelve. The nucleus of 
O. dimidiata shown in Fig. 17, Pl. XIV, is unusually clear, bring sur- 
rounded by vacuoles of the excretory organ, and in this instance 
there seems little doubt that there are twelve rows of superficial 
granules, each row probably corresponding to a chromosome. The 
chromosomes in these multinucleated forms are more granular and 
less compact than in the binucleated species. The relations of the 
chromatin spherules are difficult to make out. The resting nuclei 
show a very characteristic appearance with a superficial chromatin 
network with enlarged nodes, and one to four disc-shaped chromatin 
masses closely applied to the nuclear membrane (Figs. 99—101, 
Pl. XXI; Text Fig. X,aand 6). Ihave not yet attempted to follow 
the course of the mitosis, nor have I studied the nucleolus carefully. 
The chromosomes in multinucleated Opalinae seem to be more gra- 
nular and less compact than those in O. ¢ntestinalis and O. caudata. 
They often appear merely as rows of granules. The chromosomes 
of O. caudata and O. intestinalis are always granular as described, 
but the granules instead of being in linear aggregates are scattered 
through a mass of less darkly staining chromatin, this mass with 
its granules composing the chromosome. 
LicEer & Dusosca (19045) have described mitosis in O. satur- 
nalis in a way that is somewhat difficult to reconcile with my 
description of the phenomena in O. intestinalis and O. caudata. 
Text Fig. IV shows eight of their figures: A is a resting nucleus; 
B shows the characteristic gathering of a part of the chromatin 
into an interrupted band around the equator of the nucleus; in C 
this band is shown dividing; in D the two parts are seen migrating 
toward the poles of the nucleus; / and F' show how the daughter 
bands break into numerous parts which join the lines of granules 
(“chromosomes”) and move with them to the poles; G and H show 
telophase stages in the reconstitution of the daughter nuclei. 
Licer & Dusosce suggest that the division of the equatorial band 
of chromatin is equivalent to the ordinary splitting of the chromo- 
