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Philippine Journal of Science 
191 » 
As a rule, in dividing cells of the Ciliata, the micronuclei 
divide first by mitosis, division of the meganucleus which comes 
later being of a direct type often, apparently, in the nature of 
a more or less mechanical partition of the chromatin. 
In the case of Boveria subcylindrica, a more or less aberrant 
genus but with close affinities to the Heterotrichida, as described 
by Stevens(H), the relation between the meganucleus and the 
micronucleus at division of the former is much more intimate. 
At division the micronucleus comes to lie in contact with the 
meganuclear membrane. The spindle appears usually at one 
side, but near the posterior end of the meganucleus. Later it 
stretches along the nuclear membrane with its poles approaching 
the ends of the meganucleus. The two micronuclei when sepa- 
rated are located at or very near the poles of the dividing mega- 
nucleus. It would seem clearly indicated from this that the 
micronucleus wields a distinct influence over division of the 
meganucleus, a much more direct influence than is shown in 
Ciliates generally. 
Ikeda and Ozaki(6) have recently described another interest- 
ing relation between the mega- and micronuclei of Boveria 
labialis, a new species occurring in the respiratory trees of two 
Japanese holothurians. Unfortunately, I have been unable to 
obtain the original paper and have only seen it in abstract. The 
phenomenon was observed in conjugation. Following zygosis, 
the synkaryon divides twice. One of these daughter nuclei 
becomes the micronucleus of the reorganized individual. The 
other three products of this division undergo degenerative 
changes and become incorporated into the persisting meganu- 
cleus and may be traced in the first and second fissions of the 
exconjugant boverias. 
This merely gives a possible clue to what is going on in this 
species of Balantidium. It seems possible, and indeed is sug- 
gested by some of the figures, that the micronucleus in its in- 
corporation into the meganucleus may come to function as a 
division center within the substance of the meganucleus, sep- 
arating out and resuming its identity at the conclusion of the 
process. In a way this would merely constitute a variation 
in the process described by Miss Stevens. As to my observation 
that this constitutes a post-conjugation phenomenon, that must 
be laid aside, for the present, for the reason that no earlier 
stages of conjugation have been seen. 
Several other interesting cytological points in this species need 
clearing up, but they must be left for future work. 
