470 MONTGOMERY. [Vol. XV. 



refractive granules, and stain with eosin ; they were present in 

 one &^g, 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 



