94 Mavnarp M. MercArr, Opalina mitotica. 
has not yet begun to divide, but is still in the peculiar resting condition 
characteristic of this species. 
Fig. 11. A small Opalina just formed by transverse division. It is 
the posterior one of the pair. Its anterior edge has not yet restored its 
even contour, nor have cilia yet appeared upon this portion of the body. 
Fig. 12. Endosarc plastids: a) two plastids in side view; b) two 
plastids in edge view. 
Fig. 13. A nucleus in which one sees the chromosomes in one end 
united to form a continuous band. This condition is often seen in other 
binucleate Opalinas in slightly abnormal nuclei and in some nuclei that 
appear to be normal. 
Fig. 14. A broken individual one-half of whose nucleus projects 
from the body and is unusually clearly seen. Ten chromosomes were 
present in the exposed end of the nucleus. In the other end they could 
not be counted. 
Fig. 15. A portion of the middle of the body, showing the endosare 
plastids. Observe that the plastids in the middle, seen in side view, 
appear round or broadly oval, while those near the sides of the body, 
seen in edge view, are elongated. The plastids must therefore be disc- 
shaped, with their broad sides parallel to the surface of the body. In 
the ectosarce are seen large spaces. These contain irregular ectosarc 
plastids which are not drawn. The cilia with their basal granules are 
indicated. 
