and of other related Primula Hybrids . 365 
is for the most part cytoplasmic in staining reaction, and once more buds 
freely. Droplets of nucleolar material may adhere to the chromatic knot 
(Fig. 14). Such droplets have been recently figured by Tischler ( 40 ) 
in Musa sapientum , var. Kladi , and he suggests that they may be of an 
excretory nature. They were also frequently seen in the synaptic figures 
of Galtonia (8 and 9). 
As the synaptic knot unravels it loses its granular appearance and 
becomes more thread-like (Fig. 15). Occasional rounded chromatin 
masses are associated with the more definite lengths of spireme, and 
globules of faintly staining nucleolar material may be suspended with the 
chromatic substance (Fig. 15). The nucleolus is often pushed out first, and 
lies caught up by the loops in the clear space of the nuclear cavity. The 
appearances displayed by the loosening spireme are very various. For the 
most part it emerges in the form of loops, which stain homogeneously and 
show no longitudinal fission in their substance (Fig. 17). The looped 
spireme which comes out of synapsis and constitutes the familiar ‘ open 
spireme ’ stage is (for the most part) univalent in nature. It is, therefore, 
homologous with the univalent spireme of the somatic prophases. In the 
somatic prophases the univalent spireme segments directly into the inde- 
pendent univalent chromosomes ; in the heterotype prophases, subsequent 
to the ‘ open spireme ’ stage, a pairing of univalent lengths of spireme takes 
place, resulting in a temporary association of two univalent chromosomes, 
forming the typical bivalent heterotype chromosome. Sometimes lengths of 
thick spireme, with bifurcating ends, emerge (Fig. 16). In some cases it seems 
obvious that the univalent lengths of spireme have already joined side by 
side — have, in fact, completed the approximation sometimes prepared for in 
the heterotype prophase. Especially in superficial sections of loosening knots, 
parallel threads arranged in a ladder-like way, united by bands of chromatin, 
are constantly to be found (Fig. 18). Notwithstanding the fact that some 
of the spireme, as it emerges from synapsis, may be bivalent in nature, yet 
the greater part is univalent, and it is only later that the definite arrange- 
ment of the individual univalent lengths into pairs to form the bivalent 
combinations takes place. Thus it seems probable that the rearrangement 
during synapsis has been chiefly concerned in the formation of the univalent 
lengths of spireme, and has not participated to any great extent in the 
pairing of the homologous univalent lengths of spireme. The looped nature 
of the spireme becomes more and more accentuated, and the already 
approximated portions tend to separate and to open out (Fig. 19). At the 
places of anastomosis there is always a chromatic swelling (Figs. 19 and 20). 
During this time the nucleolus continues to bud freely. The buds 
become chromatic, and for a time remain tangled in the spireme. Some- 
times more than one nucleolus is present. 
At this and subsequent stages the nucleolus may stain either cyto- 
