2 1 8 
Allen. — Nuclear Division in the 
Fig. 84 shows an early stage in the longitudinal split ; one end of each 
V-shaped daughter chromosome is here double, the other end still undivided. 
Fig. 85 is therefore to be compared with Fig. 76, the difference in appear- 
ance between the two figures being due solely to a difference in the place 
of attachment of the spindle fibres. Fig. 87 shows two pairs of daughter 
chromosomes from the same spindle, each pair showing the completed 
longitudinal fission ; in one case the granddaughter chromosomes are only 
slightly hooked, in the other they are V-shaped. In this case, comparison 
shows that the total length of the two arms of the V-shaped granddaughter 
chromosomes is about equal to that of the single arm, with its short hook, 
of the commoner form. 
Fig. 88, PI. IX, shows the daughter chromosomes approaching one 
pole ; in Fig. 89 they have reached the diaster stage. Twelve V’s are shown 
in Fig. 88 ; in Fig. 89 the daughter chromosomes are so close together that 
it is impossible to distinguish them at their angles ; twenty-two ends turned 
away from the pole are visible, and in the preparation two others may be 
observed underneath those shown in the figure. In each of these cases, 
therefore, all of the chromosomes were originally attached to the spindle at 
their ends, and the longitudinal split of each daughter chromosome resulted 
in a single V. Fig. 90 (from a section too thin to contain all of the chromo- 
somes) represents a slightly later stage than Fig. 89 ; the chromosomes have 
been drawn closely together at the poles. A large number of f extra- 
nuclear nucleoles ’ are still present, and they show a tendency to accumulate 
in the equatorial region, in which the new cell-plate is to be formed. 
The Reconstruction of the Daughter Nuclei. 
When the daughter chromosomes reach the polar region they are 
drawn tightly together, as we have seen, the free ends of the V’s radiating 
outward and curving toward the equatorial region. These free ends now 
come closer and closer together, the ultimate result being an extremely 
dense mass (Fig. 91), in which it is difficult to trace the outline of any 
individual chromosome. At this stage a membrane appears about the 
daughter nucleus. After the membrane is formed, the nucleus begins to 
grow in size (Fig. 92), and the chromosomes become separated once more 
by clear spaces filled with nuclear sap. This growth of the nucleus is 
contemporaneous with the formation of the cell-plate and the new cell- 
wall. After the appearance of the nuclear membrane, the extra-nuclear 
nucleoles are most numerous in the neighbourhood of the daughter nuclei 
(Figs. 91-93) ; many of the nucleoles are larger than during the continuance 
of mitosis, as though some of the smaller ones had united. I have never 
seen any nucleolar substance within the daughter nucleus, however, at this 
or at later stages. This seems to be generally the case in the daughter 
