Opalina. 239 
Division of the body. 
The division of the body begins while the two parent nuclei 
are in a late anaphase of mitosis (Fig. 38, Pl. XVII), and the 
separation of the daughter cells, in normal vigorous animals, is com- 
plete during the latest anaphase (Fig. 43), or less often during the 
early telophase, when the daughter nucleus is dumbell-shaped (Fig. 42). 
In division one daughter cell receives the anterior nucleus of the 
parent, the other daughter cell receives the posterior nucleus, both 
nuclei soon completing their division and becoming double. The 
division of the body, after it begins, occupies, in the fall and winter, 
about one day. As this begins and ends generally during the 
anaphases, it is evident that the whole mitotic cycle must occupy 
many days. Less vigorous animals, weakened by being kept too 
long in unnatural conditions outside the host, may take two or three 
days for division, or may even fail to complete the division. 
Ogcasionally one sees individuals fresh from division, one side 
of whose body is drawn out into irregular strands (Fig. 43, Pl. XVII). 
This appearance is explained when one observes the last stages of 
the division itself and finds the two daughter animals united by 
such strands that have been drawn out by the efforts of the animals 
to pull away from one another. ZrtuEr described these conditions. 
Division of the body in O. indestinalis is usually longitudinal. 
In one series of preparation of individuals which were probably 
slightly abnormal, only one of the two nuclei in each individual having 
a nucleolus, I found that the conditions of the nucleolus gave a 
criterion enabling one to estimate the relative frequency of trans- 
verse division. In individuals resulting from transverse division, 
the posterior daughter cell, when its nucleus completed its division, 
showed the nucleolus in the posterior of its two nuclei; the anterior 
daughter cell, in a corresponding stage, showed the nucleolus in the 
anterior of its two nuclei. Only young anterior and posterior daughter 
cells can with certainty be distinguished by their form and general 
appearance. In these preparations of abnormal individuals the 
nucleolar relations were, without exception, as described, in the case 
of the young daughter cells, and doubtless held good for the older 
cells. In the case of longitudinal division of the body each daughter 
cell, when its nucleus divides, shows the nucleolus in the posterior 
nucleus. Eight per-cent of the individuals on these slides show the 
nucleolus in the anterior nucleus. We can therefore estimate that 
sixteen per-cent of the divisions were transverse. Probably normal 
