104 
MORPHOLOGY 
apical cell with two cutting faces, and (3) the stage of the apical cell 
with three cutting faces. It should be noted that this is one more stage 
than shown by Aneura (see p. 102), but it is not absolutely certain that 
the second stage occurs, at least with any regularity. The apical cell 
of the last stage, cutting off three series of segments, gives rise to three 
rows of leaves two dorsal and one ventral. The mature dorsiventral 
body consists of a distinct branch- 
ing axis (stem) bearing two rows 
of dorsal leaves (figs. 233-235), 
which are usually two lobed ; 
and one ventral row of very 
small leaves against the sub- 
stratum (amphigastria), variable 
in form (fig. 233). The two 
lobes of the dorsal, chlorophyll- 
bearing leaves are equal or un- 
equal; and in certain epiphytic 
forms the lower (ventral) lobe 
forms a small sac containing 
water. 
The kinds of vegetative multi- 
plication are the same as given 
under Anacrogynae (see p. 102), 
but the gemmae are usually 
tria) in the middle line, and the dorsal* leaves simpler, often consisting of only 
with their ventral lobes; 234, portion of ga- one or two Cells Separating from 
metophyte sho wine three antheridial branches; ,, , / 
rnf* Ipfir mjiT'2nris 
2 35i gametophyte with two archegonial 
branches bearing terminal sporophytes (open- Sex organs. The antheridia 
ing by four valves), and three other arche- o f Porella are on short lateral 
branches, which differ very 
much in appearance from the sterile branches (fig. 234). They are 
conspicuous on account of the closely imbricated leaves, in each of 
whose axils there is a single, long-stalked, and globular antheridium 
(fig. 236). The development of the antheridium is as described under 
Anacrogynae (see p. 102). 
The archegonia also occur on short lateral branches (fig. 235), being 
found in a group at the apex. This group is usually surrounded by a 
rosette of modified (usually enlarged) leaves. The archegonia arise 
from segments of the apical cell, and finally the apical cell itself becomes 
234 
FIGS. 233-235. -PoreUa: 233, ventral 
view, showing two ventral leaves (amphigas- 
