ike them usually to be found in process of division.

The archegonia arise from cells of the lower surface, just behind
the notch in front (Fig. 66, _F_, _ar._). Previous to their
formation the cells at this point divide by walls parallel to the
surface of the plant, so as to form several layers of cells, and
from the lowest layer of cells the archegonia arise. They resemble
those of the liverworts but are shorter, and the lower part is
completely sunk within the tissues of the plant (Fig. 66, _G_, _I_).
They arise as single surface cells, this first dividing into three
by walls parallel to the outer surface. The lower cell undergoes one
or two divisions, but undergoes no further change; the second cell
(_C_, _o_), becomes the egg cell, and from it is cut off another
cell (_c_), the canal cell of the neck; the uppermost of the three
becomes the neck. There are four rows of neck cells, the two forward
ones being longer than the others, so that the neck is bent
backward. In the full-grown archegonium, there are two canal cells,
the lower one (_H_, _b_) called the ventral canal cell, being
smaller than the other.

Shortly before the archegonium opens, the canal cells become
disorganized in the same way as in the bryophytes, and the
protoplasm of the central cell contracts to form the egg cell which
shows a large, central nucleus, and in favorable cases, a clear
space at the top called the "receptive spot," as it is here that the
spermatozoid enters. When ripe, if placed in water, the neck cells
become very much distended and finally open widely at the top, the
upper ones not infrequently being detached, and the remains of the
neck cells are forced out (Fig. 66, _I_).

The antheridia (Fig. 66. _J_, _M_) arise as simple hemispherical
cells, in which two walls are formed (_K_ I, II), the lower
funnel-shaped, the upper hemispherical and meeting the lower one so
as to enclose a central cell (shaded in the figure), from which the
sperm cells arise. Finally, a ring-shaped wall (_L_ iii) is formed,
cutting off a sort of cap cell, so that the antheridium at this
stage consists of a central cell, surrounded by three other cells,
the two lower ring-shaped, the upper disc-shaped. The central cell,
which contains dense, glistening protoplasm, is destitute of
chlorophyll, but the outer cells have a few small chloroplasts. The
former divides repeatedly, until a