223 
Centro spheres in Pellia epiphylla , Nees. 
two of these and call them centrosomes. Nor is this sur- 
prising, since even in many favourable cases of cell-division in 
animals it is by no means clear as to what is the fate of these 
bodies, whether they become diffused in the general cytoplasm, 
or whether they become retracted into the nucleus. If they 
really do persist in Pellia , the latter view seems perhaps the 
least improbable, owing to the intimate relations in space 
which always obtain between nucleus and centrospheres in this 
plant, and which have been already alluded to. 
The processes of division, as described above, are subject to 
some deviations. In a few instances, one or both of the 
centrospheres,, with their attendant radiations, were seen in 
positions apparently remote from the nuclear wall, during the 
earliest phases of division. This appearance proved, however, 
on examination, to be illusory, and to be due to the fact that 
the centrospheres had not taken up diametrically opposite 
positions outside the nucleus, so that when this body begins 
to be drawn out, it assumes an asymmetrical, or more cor- 
rectly stated, a bilaterally symmetrical shape (Figs. 3, 4). If, 
then, the distortion is very great, and the observer happens to 
regard the nucleus from the convex side, it is easy to overlook 
the oblique prolongations of the membrane, and hence the 
asters appear to be situated in the cytoplasm and away from 
the nucleus (Fig. 4). It is worth notice that in all asym- 
metrical nuclei of this nature the belt of chromatin is always 
broader on the outer than on the inner curve. 
When the asymmetrical condition becomes very strongly 
marked, a third centrosphere, often feebler than the other 
two, may be occasionally observed. We have not seen any 
simultaneous division of the nucleus into three daughter 
nuclei, although occasionally the arrangement of the chromatin 
is such as to suggest that this might occur ; as an alternative, 
it is possible that the weakest centrosphere ultimately becomes 
absorbed by one of the other two, and this we regard as the 
most likely explanation of the fact that even in preparations 
which exhibited three centrospheres, we never saw three 
spindles , or any such arrangement of cell-walls in completely 
