Andreceales. 
23 
segments. Each segment is first divided by a radial wall, and then 
tangential walls are formed which separate a central group (endo- 
thecium) of four cells from an outer layer (amphithecium) of eight 
cells, as seen in cross section of the embryo. In the upper 
segments—beginning with third oldest, and extending through three 
or four segments above this one—the archesporium is formed as a 
layer of cells cut from the endothecium, the central portion of 
which forms the columella, while the ampithecium gives rise to the 
capsule-wall. The archesporium becomes two-layered, and is dome¬ 
shaped, extending over the top of the columella, as in Sphagnum. 
The two lowest epibasal segments contribute to the foot; those 
above the archesporium produce the sterile tip of the capsule (see 
Fig. 69, A to J). 
The ripe capsule is ovoid in form, having a very short seta or 
neck connecting it below with the somewhat swollen foot or 
haustorium. The capsule-wall consists of about six layers of cells, 
at first containing chloroplasts ; the epidermal cells are thick-walled 
over the greater part of the capsule, but along four longitudinal lines 
which are equidistant from each other and reach neither the apex 
nor the base of the capsule—these lines are laid down at a very 
early stage and doubtless correspond to the primary quadrant 
divisions in the archesporium-forming cells of the embryo—the 
epidermis cells have thin walls and divide tangentially so as to 
form two superposed rows (Fig. 69, M, N). 
The venter of the fertilised archegonium grows actively, 
forming the calyptra and becoming about six cells thick ; after a 
time, when the capsule is nearly mature, the calyptra is ruptured 
and its upper portion is carried up on the apex of the capsule. As 
in Sphagnum, the axis of the archegonial shoot grows up as a 
psuedopodium, carrying on its surface some of the unfertilised 
archegonia, and expands above into a swelling in which the sporo- 
gonial haustorium is embedded (Fig. 69, K, L). When the ripe 
capsule dries, dehiscence occurs along the four longitudinal lines 
marked out by the rows of thin-walled epidermis cells already 
noted. In most cases the capsule opens by four slits, extending 
neither to apex nor base of capsule, but in some species there are 
from six to eight slits; while in A. Wilsonii (a South American 
species) the capsule is said to open by slits that reach the apex and 
extend only a short distance downwards, so that the whole tip of 
the capsule splits into from four to eight teeth. Unfortunately, the 
species just named has not been fully investigated ; careful exami- 
