GAMETOPHYTE. 37 
from the surface of the cushion they divide each into a row of cells (figs. 
208-213). The neck, therefore, consists of four rows of cells (figs. 213, 
220-222), two anterior and two posterior. The divisions always occur in 
the uppermost or next to uppermost members (fig. 210). At maturity 
the neck bends over strongly away from the growing point of the pro- 
thallus (figs. 207, 211, 219). In relation to this we find in éach of the two 
rows of cells of the neck on the convex side two cells more than on the 
concave side (4 and 6, or 5 and 7). 
Meanwhile the central cell has cut off a “‘neck canal-cell’’ (figs. 209, 
210), which pushes up in the axis of the neck. It acquires two nuclei 
(fig. 215), rarely three (fig 218). Another division in the central cell 
cuts off the ‘‘ventral canal-cell,’’ lying at the base of the neck (figs. 216, 
217, 218). The large remainder is the egg-cell. As the archegonium 
matures the neck enlarges and becomes swollen near the end (fig. 219). 
The canal-cells degenerate into an amorphous mass, the central parts of 
which stain deeply with hematoxylin. At this time also a distinct venter 
wall is formed around the egg by divisions in all the prothallial cells sur- 
rounding it (figs. 219, 223, 224). To recapitulate, the archegonium as a 
whole is made up from two sources—the neck, canal-cells, eg¢, and four 
basal cells of the venter are all derived from the original cubical arche- 
gonium mother-cell; the side walls of the venter are derived from all the 
neighboring prothallial cells. 
TABLE 8.—Development of archegonium. 
neck cel] ——___________4_ neck cells—4 rows of k cell 
Mother . ‘ penis 
cell neck canal cell;-neck canal cell, 2 or 3 nuclei 
ventral canal cell 
central coll 
ovum 
- cell_central cell 
basal cell—4 basal cells— base of venter wall 
Surrounding cells of prothallus form side walls of venter. 
When the archegonium is wholly mature, the uppermost four or eight 
neck-cells break apart, leaving a wide-open mouth (figs. 220, 224). 
Through this a transparent mucilaginous substance exudes, and may 
stream out for a distance several times the length of the archegonium 
(fig. 224). In this substance spermatozoids gather in great numbers. 
As a sperm enters the mucilage its movements become slower, and it 
changes from a short, stout helix to a long, slender one with more turns. 
The vesicle attached to its posterior end is twisted off by the resistance of 
the mucilage and floats away. The sperms swarm into the neck and 
make their way down towards the egg, which becomes pointed as though 
reaching out to receive them (fig. 223). The lower part of the neck is so 
constricted (fig. 222) that the sperms have to become nearly straight to 
get through, but many succeed in doing so. 
