286 
F. Cavers. 
The Lejeuneaceze, including Frullania, Jubnla, and the 
Lejeuneze, are sharply marked off from the remaining Acrogynze in 
the structure and development of the sporogonium. The embryology 
of Frullania has been described and figured more completely than 
that of any other genus of Acrogynze, having been investigated by 
Kienitz-Gerloff (49), Leitgeb (54), Leclerc du Sablon (52), and the 
writer (6). The first wall is transverse, the lower (hypobasal) cell 
then divides by a vertical wall and the upper (epibasal) cell by a 
transverse wall (Fig. 52, G). Each of the two upper cells then 
divides by two sets of vertical walls intersecting at right angles; 
meanwhile the two hypobasal cells also divide again by vertical 
walls, so that the embryo consists of three tiers, each with four 
cells. The hypobasal cells soon project and divide somewhat 
irregularly to form the blunt foot or haustorium which presses into 
the tissue forming the stalk of the archegonium. The cells of the 
uppermost tier divide by tangential walls into four inner cells (arche- 
sporium) with denser protoplasm than the four outer cells which 
form the capsule-wall. The middle tier divides by longitudinal 
walls separating eight outer cells from four inner ones ; this tier 
produces the stalk and lower part of the capsule. The divisions in 
the four primary archesporial cells are extraordinarily regular and 
diagrammatic. Af first only longitudinal divisions occur, until there 
is formed a lens-like mass of about two hundred cells, the central 
cells being longer than the outer ones (Fig. 52, I, J). These cells 
then become differentiated into two sets. Some divide transversely 
to form rows of spore-mother-cells ; the others grow in length but 
remain undivided, forming long cylindrical cells attached to the 
inner surface of the capsule-wall above, and to the floor of the 
capsule below. The rows of cubical sporogenous cells alternate 
regularly with the long undivided cells, each of which will form an 
elater extending the entire depth of the capsule (Fig. 53, A). Each 
elater becomes flattened and trumpet-like at the lower end, and 
contains a single broad spiral band; there are about a hundred of 
them in a well-grown Frullania capsule, those nearest the centre 
being the longest. The structure of the two-layered capsule-wall is 
very characteristic: the cells of the outer layer have rod-like fibres 
on their lateral walls, especially at the angles between adjacent 
cells, while on the walls of the inner layer the thickenings form an 
irregular net work (Fig. 53, D). The seta is not so sharply marked off 
from the capsule as in most liverworts, for at the base of the capsule 
there is a mass of thin-walled tissue corresponding to the apophysis 
