i6o Davis . — Nuclear Studies on Pellia. 
lobes of the spore-mother-cell into pairs which lie at an angle 
to one another if not actually perpendicular. The two 
spindles of the second mitosis are therefore not in the same 
plane, and a side view of one necessitates an oblique view 
of the other (see Fig. 14). These spindles present the peculi- 
arity of bending into the form of a bow so, that the poles 
may extend well into the lobes of the spore-mother-cell. This 
feature is shown in Fig. 13 as well as other characters. The 
spindle is entirely similar to that of the first mitosis, only 
smaller. It has the broad rounded poles ending in clear 
kinoplasm, and is composed of a dense mass of very delicate 
fibrillae. 
Stages of prophase are very much less conspicuous than 
those of the first mitosis, but there is a well-defined condition 
when the zone of kinoplasm surrounding the daughter-nucleus 
becomes differentiated into a mass of fibrillae. 
Following the metaphase (Fig. 13) the two sets of daughter- 
chromosomes come to lie in a region of kinoplasm clearly 
separated from the surrounding cytoplasm, at the poles of 
the spindle (see Fig. 14). In this area the daughter-nuclei 
are organized. A cell-plate appears in the equatorial region 
of the spindle, is then shortly replaced by a cell -wall, and the 
division of the spore-mother-cell is completed. 
Because of the order in which these cell-walls are laid 
down the arrangement of the spores is not tripartite. How- 
ever, the four portions diverge in such a symmetrical manner 
that sections frequently give the appearance shown in Fig. 15, 
but in this case it is plain that the first wall laid down runs 
from a to b. The nucleus in each spore immediately passes 
into a resting condition in which the chromosomes break up 
into granules that become distributed through the interior. 
The linin network does not appear until the nucleus becomes 
much larger and has taken its final position near the centre 
of the cell. 
We will now consider the structure and behaviour of the 
chromosomes. They are eight in number in the mitoses of 
the spore-mother-cell and in the germinating spore, and sixteen 
