370 Digby . — The Cytology of Primula kewensis 
preparations there has always been a considerable amount of contraction 
which is displayed by the crinkled edges of the cytoplasm. Gradually, as 
the second contraction becomes sorted out r the protruding portions of 
spireme thicken considerably, and clearly show their bivalent nature. Some- 
times in the same nucleus (Fig. 46) some of the chromosomes may be almost 
fully formed, whilst the outline of others may be but indicated by the union of 
univalent spireme lengths, recallingthe figures in the realization of the biva- 
lent segments in P .floribunda. As the bivalent chromosomes emerge from 
the second contraction, they are often in the shape of rings joined together 
like the links of a chain (Fig. 47). Several rings may go to form one bivalent 
chromosome, for a large loop of spireme may become constricted in one 
or more places, resulting in a spectacle-shaped or chain-like chromosome. 
When the nine bivalent chromosomes have been evolved out of the 
confusion of the second contraction they tend to segregate into two groups, 
and often the chromosomes in these groups become so pressed together 
as to lose their visible individuality (Fig. 48). Sometimes the chromosomes 
split into their univalent halves after they have issued from the second 
contraction. In that case the usual deeply staining, unsplit portions can 
be sharply distinguished from the symmetrically arranged, lightly stain- 
ing, newly split univalent halves (Fig. 50). Under favourable conditions, 
but very rarely, the longitudinal fission in the but lately split limb can 
be seen (Fig. 49). The univalent chromosomes remain attached at one 
end, condense, and thicken considerably, and adopt the typical heterotype 
form (Fig. 51). There are always several large ring chromosomes. A 
transverse section of an equatorial 'plate shows the nine diagrammatic 
chromosomes (Fig. 52). The spindle is at first quadripolar, then becomes 
bipolar, and the univalent chromosomes proceed to the poles in the normal 
way. At the late telophase of the first meiotic division, or the early pro- 
phase of the second meiotic division, the nine longitudinally split chromo- 
somes are beautifully clear (Fig. 53). 
There is nothing further to add about the homotype division. It 
has already been mentioned that the pollen-grains of P. verticillata are 
larger than those of P . floribunda. 
P. KEWENSIS (type). 
The stages prior to the coming out of synapsis are like those of 
P. floribunda and P . verticillata. 
In the formation of the bivalent segments, P. kewensis (type) adopts 
a method intermediate between the simple pairing of univalent strands 
characteristic of P. floribunda and the well-marked second contraction of 
P. verticillata. Although P. kewensis has no definite second contraction, 
there are small, isolated, thickened, chromatic areas to be found, formed 
by the massing, in places, of several univalent segments. 
