262 M. M. Mercatr 
chromosomes really occurs during the telophases. If, on the other 
hand, the chromosomes and their contained granules do not divide 
into equivalent parts in each division of the nucleus, it seems that 
nuclear division in Opalima must be much simpler than mitotic di- 
vision in higher forms. 
I at first inclined toward the first hypothesis in interpreting the 
mitosis in Opalina and tried to imagine how these daugther chro- 
mosomes, formed in the telophase, could pass into the spireme and 
reappear later in the next double equatorial plate. Three salient 
facts are seen: 1) the fusion of the chromosomes in the late telo- 
phase is not a union end to end, but is instead an irregular lateral 
union, more or less broad plates of chromatin passing from the side 
of one chromosome to the side of the next, until they all become 
united to form the chromatin ribbon, 2) the chromosomes when 
they again become distinct, previous to the next mitosis, arise by 
transverse constriction of the chromatin ribbon and 3) the chromo- 
somes remain permanentle, attached at each end to the poles of the 
nucleus by means of fibres some at least of which do not split. 
The transverse constriction of some of the chromosomes in the early 
telophases is a transient phenomenon, all the unconstricted chromo- 
somes and the parts of the constricted chromosomes soon completely 
fusing in the spireme. 
If the eight chromosomes split longitudinally in the telophase 
and then unite laterally to form the chromatin ribbon of the spireme 
stage, this ribbon might consist of the sixteen daughter chromosomes 
lying side by side in a single row. When now the spireme con- 
stricts transversely to form the sixteen chromosomes of the next 
mitosis, these might be the original sixteen daughter chromosomes 
from the longitudinal division in the last telophase. On the basis 
of such a schema, the relations of the granules in the chromo- 
somes would not be very difficult to bring into harmony with the 
usual conception of the chromosomes as consisting of a linear aggre- 
gate of chromioles which retain their individuality and which, in 
division, give one half of their substance to each daughter chromo- 
some. But the chromosomes which in the telophase show appearance 
of splitting do not, as already noted, show their granules arranged 
in pairs, so that we have, even on the basis of this schema, no 
satisfactory indication that equivalent daughter chromioles are 
distributed in the daughter chromosomes to each daughter nucleus; 
and furthermore, the attachment of each end of each parent chromo- 
some to the corresponding pole of the nucleus by means of a per- 
