204 Sargont. — Formation of the Sexual Nuclei 
they extend towards the chromosomes. The spindle thus 
formed is rarely symmetrical at first (Figs, io a, 1 i, n a) 1 . 
The chromosomes soon begin to scatter, being attached to 
bundles of fibres (Fig. n a). 
As the spindle becomes symmetrical, the chromosomes are 
arranged in an equatorial plate. Two very well-marked 
bundles of spindle-fibres are then attached to each chromo- 
some (Fig. 12) 2 . One of these bundles is fixed to each 
segment, and they point to opposite poles. The two seg- 
ments move apart from each other as if each were pulled to 
its pole by the fibres attached to it. During the process of 
separation the whole chromosome becomes much contorted. 
This is not surprising when we consider how tightly the 
segments of each chromosome are usually twisted on each 
other, and that they must untwist as they are pulled apart. 
Adjacent chromosomes may assume very different shapes 
(Fig. 12). This depends very much on the point of attach- 
ment of the spindle-fibres, which may be in the middle of 
the chromosome or near one end. The knotted and strained 
appearance of the segments just before complete separation is 
much less conspicuous here than in the first division of the 
embryo-sac nucleus (I, p. 462). Compare for instance Fig. 13 
in this paper with Fig. 23 in Part I. It seems as if the strength 
of the pull exercised on the chromosomes by the spindle-fibres 
varied to some extent with the size of the cell. 
The daughter-chromosomes in the diaster-stage are com- 
monly V-shaped, the angle pointing towards the pole which 
it approaches (Figs. 13, 14). This angle is often bent back 
(Fig. 14) 3 . When the two groups of daughter-chromosomes 
reach the poles, they cluster closely together, and the deflexed 
angle forms part of a depression in the daughter-nucleus — 
the ‘ polfeld.’ A cell-plate is formed between the two nuclei 
(Fig. 15), and is shortly followed by a cell-wall. 
1 W. Belajeff, Zur Kenntniss der Karyokinese bei den Pflanzen, Flora, Erganz- 
ungsband, 1894, p. 438. 
2 W. Belajeff, 1. c. p. 439. See particularly Fig. 15 from L. candidum. 
3 See Postscript. 
