BRYOPHYTES 107 
Antheridium. The antheridia are embedded in the thallus and are 
therefore hard to detect (fig. 237). The antheridial initial is a superficial 
cell, but it does not develop a papillate protrusion as in the other liver- 
worts. A transverse (periclinal) wall divides it into an outer and an 
inner cell. In the other groups the outer cell develops the antheridium, 
but in Anthocerotales the antheridium is developed from the inner cell. 
By a succession of anticlinal and periclinal divisions, the outer cell 
produces two layers of cells, which form an outer wall or roof to the 
antheridial chamber. 
The inner cell develops one to several antheridia. The method of development 
of an antheridium, whether directly from the inner cell or from one of its daughter 
cells, is as follows : two vertical walls at right angles to each other result in four 
cells ; transverse walls result in several tiers of four cells each ; periclinal walls in 
the upper tiers cut off an outer wall layer and an inner group of spermatogenous 
cells ; and the lower tiers (sometimes only the lowest) develop a more or less elon- 
gated stalk. The antheridium or group of antheridia thus produced lie in what 
may be called an antheridial chamber (fig. 237). 
Archegonium. The archegonia also are in the tissue of the thallus. 
in this respect resembling the archegonia of pteridophytes (fig. 238). 
In all other bryophytes they are entirely 
superficial structures. As a result of this 
relation to the thallus, there are no sterile 
jacket cells (neck and venter) very dis- 
tinct from the adjacent cells of the thallus. 
The essential part of an archegonium, 
however, is the axial row, and in the 
Anthocerotales this is the only distinct FlG 2 ^' J Anthoceros : arche . 
Structure. gonia, showing " embedded" char- 
acter; in the archegonium to the 
The general outline of development of this right the complete axial row is 
axial row is as follows : a superficial cell divides shown (beginning below, the cells 
transversely, giving rise to outer and inner cells ; are the e SS, ventral canal cell, and 
the outer cell divides transversely, giving rise to four neck canal celk ) ^PP 6 " 3 b ? 
., ,, , ,, . . , , , , the neck cells (two visible) : in the 
the cap cell and the primary neck canal cell; the 
... , archegonium to the left, the neck 
inner cell is the primary ventral cell; the primary a iU 
J cells have been thrown on, the 
neck canal cell, by two successive divisions, canal cells have disor g an i ze d, and 
develops a row of four neck canal cells ; the t h er e is a passageway open to the 
primary ventral cell, by a single transverse egg, which is ready for fertilization, 
division, forms the ventral canal cell and the 
egg. At maturity the cap cells are thrown off, the neck and ventral canal cells 
break down, and a broad canal is open to the egg (fig. 238). 
