Marquette—Spore Mother-Cells of Marsilia. 101 
As the chromosomes move back to the poles, the polar ends 
of the spindle become markedly darker and more compact 
(Fig. 14 b). This stands out even more strikingly in the 
preparations than in the drawing, where only a section of the 
spindle is represented. The spindle shown in Figure 14a is 
essentially of the same appearance as that in Figure 14 h; the 
right hand pole, however, is represented lighter because it lies 
deeper in the section; the left hand (higher) pole, on the other 
hand, has a large proportion of its fibers in the next section 
above, so that it does not appear heavy in the drawing. The 
spindle figures at this stage show well-developed connecting 
fibers running from pole to pole, and it can readily be seen 
that some of them lie distinctly outside of the chromosome 
group. Delicate radiations extend out from the poles of the 
spindle towards the equatorial region; at times radiations from 
the two poles cross in the equatorial region. Although deli¬ 
cate, these fibers because of their distinct blue stain stand out 
sharply in the preparations against the orange-gray background 
of the other cytoplasmic structures. The poles of the spindles 
frequently do not reach to the plasma membrane. Occasion¬ 
ally, in what otherwise seem to be somewhat abnormal cells, the 
spindle poles are unusually sharp and compact and end directly 
at the plasma membrane ; if the cells are somewhat shrunken, 
the plasma membrane is markedly pushed out at the points 
where the spindle poles are in contact with it. More or less 
curved spindles also are not rare. 
After the chromosomes reach the poles and the daughter 
nuclei are reconstructed, the starch is so distributed that about 
an equal amount is contained in each of the four cells result¬ 
ing from the development of cell-plates by means of the con¬ 
necting fibers between the nuclei. 
The spore mother-cells of Marsilia show for a considerable 
period of their existence a well-marked polar organization. 
In the earlier stages, the visible expression of this as far as 
the cytoplasm is concerned is the characteristic position of the 
starch grains in the cell. There is no evidence of their being 
enclosed by an enveloping membrane as is the case in young 
