88 & MaynArD M. METcALF, 
nucleus, and not two half nuclei, is given to each daughter cell. 
The condition in Opalina is not a true binucleated condition. We 
have merely a delayed division of the body, which causes two 
daughter nuclei to lie for a long time in one cell, indeed even until 
they have entered upon the next mitosis. Division of the cell, when 
it does occur, is not associated with the mitosis in the nuclei which 
is taking place at the same time, but is really the delayed cell- 
division that belongs with the last nuclear mitosis. Division of the 
cell-body lags one step behind the division of the nuclei. To get a 
proper understanding of the real meaning of this division we must 
bring together that division of the body and that division of the 
nucleus which really belong together. 
“In attempting to do this we see at once that the direction 
of the division of either nucleus or body must be changed. At 
present the long axes of nuclei and body coincide and remain con- 
stantly in this relation. The nucleus divides transversely and 
the body generally longitudinally. Can we find a plausible 
scheme which will get around this difficulty ? 
“The present con- 
dition in Opalina, with 
an apparent but not 
a true binucleated 
state, could be changed 
into atrue binucleated 
state comparable to 
that of Paramoecium, 
if cell-division should 
change from longi- 
a b e tudinal to transverse 
Fig. A. and at the same 
time should bisect 
each of the two nuclei. Instead of the condition shown 
in Text Fig. IX. A (here copied in Fig. A,a), as now, we would 
have that illustrated in Text Fig. IX, C (here Fig. A, c) each cell 
receiving two daughter nuclei instead of one whole nucleus. From 
this condition, that of Paramoecium could be reached by functional 
and accompanying structural divergence of the nuclei, as suggested 
above. The ordinary infrequent transverse divisions of the binucleated 
Opalinae do not help us in this schema, for they do not bisect the 
nuclei (Text Fig. IX, B, here Fig. A,b). The false binucleated con- 
