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[Vol. XV. 
refractive granules, and stain with eosin ; they were present in 
one egg, close to, and opposite, the two poles of the nucleus, 
before the nuclear membrane had disappeared (Fig. 316), so that 
they may be extranuclear in origin. The radiations of the asters 
are very clear, especially after fixation in Flemming’s fluid, and 
may be traced nearly to the cell membrane. Immediately 
around each centrosome a central portion of the aster is dif¬ 
ferentiated, namely, an attraction sphere (in the terminology of 
van Beneden), and this differs from the remaining portion in 
staining less intensely, and appears to be quite sharply bounded 
from it. In this attraction-sphere the cytoplasmic granules are 
smaller and more densely grouped, so that at first sight it 
might appear to consist of a homogeneous “ archoplasm,” but 
careful study shows that in it the cytoplasmic microsomes are 
arranged in radial rows around the centrosome, and each of 
these rows appears to be continuous with a ray of the outer 
aster. Or, to express it differently, the microsomic rays of the 
sphere extend to the centrosome, but this terminal part of each 
ray differs from the remaining distal portion in that its micro¬ 
somes are smaller and closer together. Thus in Piscicola the 
finer structure of the attraction-sphere seems to have much 
resemblance to that of Ascaris, as described by Kostanecki and 
Siedlecki {Arch. mikr. Anat ., 48, 1896). 
It remains to describe the mode of arrangement of the ova 
within each ovarial acinus. The proximal, small end of the latter 
is filled with small ovogonia (the youngest stages), and from 
mutual contact these are polygonal in form (Fig. 300). As we 
proceed towards the distal end of the acinus (Fig. 301) the ova 
not only become gradually larger, but have a different arrange¬ 
ment, in such a manner that they become epithelially grouped 
along the wall of the acinus, each cell having a pyramidal 
shape, with its apical end directed towards the central cavity 
of the acinus. A little more distally in the acinus (Figs. 302 
and 303), the ova become not only larger, but fewer of them 
are to be found on a given transverse section of the acinus ; the 
individual ova have more of an oval shape and become sepa¬ 
rated from one another. Now when we proceed still further 
towards the distal end of the acinus (Fig. 304) we find a single 
