368 Digby. — 'The Cytology of Prirmda kewensis 
plate is very neat, the chromosomes, dumb-bell or kite shaped, being 
arranged in perfect symmetry. A transverse section of this stage shows 
the nine chromosomes (Fig. 34). Gregory (24) has found the reduced number 
of chromosomes in P. sinensis to be twelve. 
The nucleolus disappears as the chromosomes go on to the spindle. 
The separation of the univalent chromosomes and their retreat to the 
poles, to which they are drawn by stout spindle fibres, is very clearly 
demonstrated. The chromosomes are round or oval in shape, they 
stain deeply, and show no sign of longitudinal fission (PI. XLII, Fig. 35). 
Arrived at the poles, they at first, in the usual manner, mass together and 
lose their individuality. Then they separate, fine threads join the segments 
one to the other, a nucleolus makes its appearance, and the nucleus becomes 
bounded by a limiting membrane. Cytoplas mic connexions passthrough 
the cell zvalls and join diasters of adjacent cells to one another (Fig. 36). 
These connexions may be observed at earlier stages, but they are the more 
striking at the diaster, when the cytoplasm, contracted from the cell-walls, 
is mainly collected round the spindle. The fact that these cytoplasmic 
strands pierce the cell-walls gives a possible explanation for the transit 
of the chromatin bodies from one cell to another (8). Gates (15) has 
figured similar protoplasmic connexions between the pollen mother-cells 
of Oenothera rubrinervis. 
To return to the telophase. The stages leading from the heterotype 
to the homotype division are extremely quickly passed through, in fact 
sometimes the chromosomes appear at once to reconstitute themselves. 
The more or less homogeneous masses of chromatin, representing the 
individual chromosomes, split longitudinally (Fig. 37), their sides become 
beaded (Fig. 38), and fine threads join the various portions to one another. 
The nearest approach to a resting stage that has been found is a nucleus 
containing the skeleton of each chromosome clearly outlined by granules, 
and amongst them some indeterminate groups of granules (Fig. 38). 
The prophases of the homotype are indistinguishable from the telo- 
phases of the heterotype division, and the only means of recognizing the 
one from the other is that, by the time that the chromosomes are recon- 
stituting themselves, there is no trace left of the spindle fibres of the 
heterotype division. The chromosomes are re-formed by the concentration 
of the granules. They show complete longitudinal fission, the two halves 
being in the same relative position to one another as the limbs of a V 
or of an X (Fig. 39). The figures are markedly tetrad-like in character 
(Fig. 40). Sometimes the fully formed chromosomes are composed of con- 
centrated chromatin, sometimes they are beaded. Spindle fibres appear, 
and the chromosomes attach themselves irregularly (Fig. 40), but they 
finally collect at the equator, where they form a neat circle of dyads 
(Fig. 41). One spindle is generally at right angles to the other, but 
