598 MurrilL—The Development of the Archegonium 
The mature spindle is broad, with many fibres and rather 
blunt ends, and, during the metaphase, the twenty-four chromo¬ 
somes occupy all of the equatorial plane (Figs. 50, 51). The 
type of this division, so far as the chromatin is concerned, is 
the same as that already described for the central cell of the 
archegonium. The position of the mature spindle in the nuclear 
cavity seems independent of the relative position of the con¬ 
jugating nuclei, and, while the division is usually oblique, it 
may be perpendicular to, or parallel with, the longitudinal 
axis of the archegonium (Figs. 52, 54, 57). 
The chromosomes pass to the poles as slender undulated 
V’s or U’s, and fuse to form the network of the daughter- 
nuclei (Figs. 53, 54). No cell-plate is formed, but the fibres 
fade away into the cytoplasm, the slightly thickened middle 
portions being the last to disappear. 
The pro-embryo. 
The two free nuclei resulting from the first segmentation 
increase rapidly in diameter, and soon divide simultaneously 
without change of position to form four nuclei of equal size 
lying free near the centre of the egg (Figs. 54-58). The type 
of the second division is similar to that of the first, but the 
spindle is narrower and more pointed at the ends (Fig. 56). 
The daughter-nuclei are formed and the spindle-fibres absorbed 
as in the first division. When the four nuclei have attained 
their full size, they move to the base of the archegonium 
(Figs. 59, 60), and by successive divisions in a horizontal plane 
give rise to four tiers of nuclei with four nuclei in each tier, 
as has been already described for various Conifers. 
When the four free nuclei are moving through the egg- 
cytoplasm they do not show any special collections of fibres 
about their membranes, but soon after the base is reached 
they become enclosed in a dense mass of fibrous substance 
(Fig. 60), which supplies the material for the walls that appear 
later. Above this fibrous mass is a zone showing a delicate 
reticulum almost devoid of stainable substance. Above this 
