6c>4 Mur rill—The Development of the Archegonium 
part of the chromatin is in the upper half of the nucleus. Activity has now begun 
at the upper pole, where delicate fibres are seen growing down against the nuclear 
membrane, but it rarely appears so distinct as in this preparation. 
Fig. 19. ( x 800.) This nucleus belongs to a larger archegonium than that 
shown in Fig. 18. The spindle is in about the same stage, but the chromosomes 
are more advanced than those shown in the preceding figure. Radiations are 
present at the upper pole, and possibly a small polar cap, but the latter, if present, 
is not distinct enough to figure. 
Fig. 20. (x 800.) This figure represents the same stage as Fig. 19, but the 
nucleus remains spherical, and the spindle-fibres seem to have originated at 
a greater distance than usual below the nuclear membrane, and to have advanced 
with a more even front. This is exceptional, being observed only a few times in 
the examination of a large number of preparations. 
Fig. 21. (x 800.) The nuclear membrane has disappeared opposite the poles, 
and the spreading cone-shaped bundles of spindle-fibres have grown into the 
nuclear cavity, and are uniting somewhat above the centre of the nucleus. The 
true pear-shaped form of the nucleus and the inequality of the two poles cannot be 
shown in a longitudinal section which includes the upper pole, since the division is 
oblique and much of the lower pole is cut away. When first formed, the spindle 
is broad and the chromosomes, which have now become homogeneous, are attached 
to its outer threads. 
Fig. 22. (x 800.) The spindle-fibres are now homogeneous throughout, and 
the spindle has narrowed and drawn in the completed chromosomes nearer to the 
centre. In narrowing, it has also elongated, and the upper pole has been elevated. 
The section is made as in Fig. 21, and does not show all of the lower pole. 
Fig* 2 3 * (x 800.) Further narrowing of the spindle has taken place, and the 
chromosomes are now coming up to the equator, preparing to enter the plate stage. 
The equatorial portion of the nucleus approaches very near the wall of the egg, 
and above this line the small cap of cytoplasm is dense and full of fibres. 
Fig. 24. ( x 400.) The lower pole of the mature spindle is here represented. 
The fibres come to a definite point, and, in this case, focus on a small hyaline 
granule, which shows none of the properties of a centrosome. 
Fig. 25. (x 400.) The fibres of the mature spindle also converge to a definite, 
though rather abrupt, point at the upper pole, from which supporting fibres extend 
to the cell-wall. The remainder of the nuclear membrane also appears to function 
as a support to the spindle during metakinesis. 
Fig. 26. (x 800.) Separation of the chromosomes has begun at the nuclear 
plate, the bundles of mantle-fibres being attached on opposite sides of the diamond¬ 
shaped openings in the chromosomes already seen in earlier stages. 
Figs. 27, 28. ( x 600.) The daughter-chromosomes pass to the poles as U’s or 
V’s with undulated margins. After they reach the poles, the central spindle-fibres 
appear lax, and the spindle becomes slightly concave in the equatorial region. 
This may be due to artificial causes or to relaxation after removal of the strain. 
Fig. 29. ( x 400.) The daughter-chromosomes have united into a close, deeply- 
staining spirem, but no membrane is yet formed about them. The inner spindle- 
fibres are beginning to thicken in the equatorial region preparatory to the formation 
of the cell-plate. 
Fig. 30. (x 400.) The dispirems have opened out, but their loops still 
maintain a position parallel with the axis of the spindle. Delicate nuclear mem- 
