OXNERELLA MARITIMA. 
527 
grate, and pass on to the spindle-fibres (PL 27, figs. 1 1-14), 
which are very dark and granular between the “ asters” and 
the equatorial plate (PI. 27, fig. 14). I have found no spireme 
stage in the prophases, but am not prepared to deny its 
occurrence. 
I have not succeeded in counting the chromosomes on the 
equatorial plate. They are extremely small and in the form 
of short rods so closely packed together (PI. 27, fig. 14) that 
their number can only be roughly guessed. As the equatorial 
plate is probably in the form of a ring, and as rather more 
than ten chromosomes can as a rule be counted across it when 
presented edgewise, I estimate the chromosome number as 
probably about twenty-four. 
There are some peculiarities in the spindle which require 
further notice. At all stages, after it is fully formed, it 
shows a differentiation into two parts, which do not stain 
alike. There is, first, an unstained or achromatic central 
area immediately surrounding the equatorial plate (PI. 27, 
fig. 14), so that the whole of the middle part of the spindle may 
be compared with a tiny clear globe with the chromosome 
ring forming its equator. Secondly, there is, on either side 
of the clear central part, a more deeply-stained and granular 
portion of the spindle which resembles a truncated cone with 
its apex directed towards the centroplast (PI. 27, figs. 14, 15). 
The cones become paler in the region of the centroplasts, and 
the ends of the spindle-fibres appear to be rooted partly in the 
central granules of the latter, and partly in their membranes 
(PI. 27, fig. 14). There is no sharp demarcation between the 
achromatic central part of the spindle and the stainable cone- 
like ends, so that the two parts appear to be differentiations 
of one and the same structure — the spindle — rather than 
separate elements. They are, no doubt, respectively homolo- 
gous with the so-called “ polar plates” and “ achromatic 
cones” described in the mitotic figures of Actinosphaerium 
(cf. Brauer (1894), R. Hertwig (1898) ). 
Metaphase. — The chromosomes on the equatorial plate 
now divide so that two daughter-plates are formed. It is not 
