THE PLACENTAS IN THE TRIBE ALSINER. 425 
appear than in Lychnis; whereas in Lychnis only two pairs of 
ovules are developed on the free margins of each dissepiment ; in 
Dianthus barbatus there are four pairs; and although the prin- 
ciple holds good that the ovules in the upper part of the capsule 
are the first to develop, it must be noted that the uppermost pair 
of ovules are always, so far asI have observed, later in develop- 
ment than the pair immediately below them. There is sometimes 
an indication of a similar tendency in Lychnis. 
Sagina apetala is a member of the group Alsinez, in which the 
development of the capsule resembles that of Lychnis extremely 
in its early growth, and does not differ from it much in its later 
stages (Pl. XX XIII. figs. 1-8). When the staminal whorl has 
appeared, the carpellary whorl arises as four blunt prominences 
round the base of the slight central elevation; these soon take 
the form of four shallow pockets. As the capsule increases in 
length, the pockets or loculi become deep and narrow in a radial 
direction, their upper edges keep almost on a level with the 
central elevation, and their four dissepiments nearly meet in a 
cross-like manner at its apex. This they surmount before the 
appearance of the ovules (Pl. XX XIII. figs. 4-7). Later, the 
capsule becomes narrower and closes over above; the walls of each 
loculus grow upwards to form one of the four stigmas. The 
lower part of the capsule is four-locular, and upper unilocular, 
being incompletely divided by the dissepiments. When the 
flower opens, the dissepiments have broken away from the lateral 
walls of the capsule, but remain adhering to its roof as four loose- 
tissued bands: these become detached during the further growth 
of the capsule after flowering (Pl. XXXIII. fig. 8). 
The early stages of the development of the capsule of Spergula 
arvensis are similar to those of Lychnis before the appearance of 
the ovules (Pl. XXXIII. figs. 9-14). As in that species, five 
blunt carpellary prominences arise around the base of the slight 
convex central elevation. As in Lychnis, and as also in Sagina 
apetala, the loculi appear at first as slight depressions of a trian- 
gular shape (the bases of the triangles being directed outwards); 
but whereas in Sagina apetala the loculi soon become narrow 
throughout their whole length, in Lychnis and Spergula they 
only narrow below, and remain triangular in section above 
(PL XXXIII fig. 10). As in Lychnis, the capsule-walls and dis- 
sepiments grow up, keeping on a level with the central elevation 
fora considerable time; then they begin to rise above it. When 
