174 
Mottier.—Nuclear and Cell Division 
segments separating first at one end, so that a V-shaped 
figure immediately results (Fig. 9). The radiations are also 
divided, as a cluster is attached to each daughter centrosome. 
It is inferred that the centrosome splits longitudinally in 
division, from the manner in which the kinoplasmic radiations 
are attached to the daughter centrosomes, and from the fact 
that these bodies are always rod-shaped and nearly of the 
same length. 
The daughter centrosomes now separate, moving along 
the nuclear membrane, but do not, as in the first mitosis, 
traverse an angular distance of 180 0 before the formation 
of the spindle begins (Figs. 10, 12, 13). From each centro¬ 
some a diverging bundle of fibres enters the nucleus, which 
contains a very fine network of linin with small scattered 
chromatin masses and a large nucleolus (Fig. 11). In this 
figure only one pole of the spindle-rudiment is shown, the 
other being in another section. At a little later stage these 
fibres form cone-shaped collections with their bases directed 
toward the chromatin, and a deeply staining mass, which 
is probably the disorganizing nucleolus (Fig. 12). This stage 
of the karyokinetic figure bears a striking resemblance to that 
observed by Harper (’ 97 ) in certain Ascomycetes. As the 
spindle-fibres within the nucleus increase in number, the 
polar radiations diminish, so that often only very feeble 
asters remain (Figs. 12, 13). The bases of the two cones of 
fibres unite to form a curved spindle, while at the same time the 
chromatin is arranged in the equatorial region ; the nucleolar 
mass gradually becomes less and finally disappears (Fig. 13). 
The granular network still persists until a later stage, and 
seems to take no part in the formation of the spindle, or, at 
most, plays only a secondary role. The nuclear membrane 
disappears soon after the spindle is mature, generally before 
metakinesis, but the outline of the nuclear cavity now occupied 
by the karyokinetic figure may be distinguished at a later 
stage. The spindle of the second mitosis is smaller than that 
of the first, and may remain slightly curved until meta¬ 
kinesis. The orientation of its fibres is the same, and the 
