500 Campbell. — The Development of 
In a few cases two antheridia were seen within the same 
envelope. They were strongly flattened on the side where 
they were in contact, but there was no means of deciding 
whether or not they originated from a common mother-cell. 
The Archegonium. 
The female plant does not differ much from the male, but 
is possibly a little larger, as a general thing, and more freely 
branched (Figs. 21, 22). Like the antheridia, the archegonia 
arise from superficial cells near the apex of the shoot, and at 
first are hardly distinguishable in form from the youngest 
antheridia. The mother-cell of the archegonium, however, 
is somewhat larger and more enlarged above. The first 
wall corresponds to that in the young antheridium, and is 
nearly level with the surface of the thallus. The second wall 
is also horizontal, as in the antheridium, but it is formed in 
the lower of the two primary cells, instead of in the upper 
one, which becomes at once the archegonium proper, the two 
lower cells forming the short pedicel (Fig. 24). The form 
of the mother-cell of the archegonium, as well as the first 
division, correspond very closely with the same points in 
Sphaerocarpns , the greatest difference being the position of 
the first wall, which is higher up in Sphaerocarpns , so that 
later the archegonium is raised above the level of the thallus. 
The first divisions in the upper cell are those typical of the 
Liverworts in general. The usual three intersecting walls 
arise, cutting off the axial cell (Fig. 25), from which later the 
egg-cell, canal-cells, and cover-cell are developed. Then 
each of the primary peripheral cells is bisected by a second 
vertical wall, after which by horizontal walls in all the cells the 
archegonium-rudiment is divided into two tiers, constituting 
respectively the venter and neck. Before this takes place, 
however, the cover-cell has been* cut off from the axial cell. 
The archegonium now (Fig. 26) consists of six peripheral rows 
of cells enclosing an axial row of three cells. The cover-cell 
next undergoes division into four by cross-walls, and the two 
