KARYOKINESIS AND ITS RELATION TO FERTILIZATION. 177 
the chromatic figure. Accordingly, the figures of Strasburger, 
as well as those of Flemming, Rabl, &c., of the final phase 
of the “skein” no longer show a boundary to the nucleus, 
but only a clear area round the thread figure which differs 
more or less in shape from the earlier outline of this nucleus. 
How the mixture of the nucleoplasm with that part of the 
cell-protoplasm concerned takes place, most authors (with 
the exception of Strasburger)} leave undecided. The above- 
mentioned clear area at which the nuclear- and cell-substance 
meet after the disappearance of the nuclear membrane has 
been especially described by Flemming and Rabl, and we shall 
refer to this point later on. 
Finally, mention must be made of van Beneden’s “ pole- 
bodies” (Polkérperchen), which on the complete formation of 
the spindle figure appear at its poles (figs. 7 and 8). He dis- 
covered them in the egg of Dicyema (19). They are small 
shining bodies which must be regarded as independent struc- 
tures, not as expressions of the junction of the spindle-threads. 
Their origin and meaning are still unknown. Carnoy (47) 
looks on them as stores of nuclear material which are partly 
formed from cytoplasm, and which are used up later on in the 
reconstruction of the daughter nuclei. 
In plant-cells ‘ pole-bodies ” have not been hitherto observed 
(Strasburger). . Polar rays exist here, though rarely (see 
below for polar rays and pole-bodies, as well as for the struc- 
tures known as “ attraction spheres” of van Beneden). 
After the spirem stage, which we have up to this moment 
been describing and which terminates with the completion 
of the longitudinal splitting of the chromatic threads, there 
now follows the stage which is termed the “ mother star,” 
“ aster,” or “‘ monaster” (fig. 7). The peculiarity of this is 
the arrangement of the chromatic loops around the equatorial 
plane of the spindle figure in such a way that the angles of 
the loops are directed towards the centre of the spindle and 
the limbs peripherally. Flemming was the first to describe 
the process. As he previously pointed out, the equatorial region 
of the spindle figure is a sort of area of attraction for the 
