Davis —Nuclear Studies on Pellia . 169 
of asters, and such an example is shown in Fig. 36. The two 
bodies there figured were conspicuous in a cell that contained 
very little cytoplasm, so that the interior was chiefly given up 
to vacuoles. The arrangement of the radiating strands of 
protoplasm is very suggestive of an aster, and the association 
with an elongated nucleus about to enter prophase lends 
favour to such a possibility. But the writer does not believe 
that these structures have anything to do with asters. They 
are merely an exceptionally regular and delicate arrangement 
of strands of protoplasm passing from the periphery of the 
cell to the interior and converging to points near the ends of 
the elongated nucleus. Such arrangements are very frequent 
in the cells of the seta, and are generally so well defined that 
their character is unmistakable (see Fig. 37). They are the 
strands of protoplasm that swing the nucleus in the centre of 
the cell. Although usually broad and distributed irregularly 
as in Fig. 37, the strands may be so delicate and symme- 
trically disposed as to resemble an aster. 
When the spindle is to be developed the protoplasm begins 
to collect at the poles of the elongated nucleus. There is 
little in the structure or morphology of these accumulations 
to indicate their kinoplasmic nature. Like the rest of the 
cytoplasm they are rather free from granules, and do not 
stain deeply. That these arrangements are kinoplasmic is 
shown by their further history. They form caps over the 
ends of the elongated nucleus, as is shown in Fig. 38. By 
changing from a granular to a fibrous condition the caps 
become the poles of the spindle. This history is then 
in essential agreement with the conclusions of Hof (’ 98 ) 
and Nemec (’ 99 ), who have so thoroughly studied spindle- 
formation in vegetative tissue, and especially root-tips, in a 
variety of forms. 
After the dissolution of the nuclear membrane the spindle- 
fibres grow rapidly into the nuclear cavity, carrying the 
segments of the spirem-thread to the centre of the nuclear 
figure (Fig. 39). There the chromosomes, probably always 
sixteen in number, are found at the nuclear plate (Fig. 40). 
