496 MISS G. LISTER ON THE ORIGIN OF 
this has continued for a short time, the close resemblance between 
the development of Lychnis and that of Spergula and Sagina 
ceases. In Lychnis the dissepiments mount well above the 
central elevation before the ovules appear; when they do appear, 
the first are formed on the free projecting plates of the dissepi- 
ments, as has already been mentioned (Pl. XXXII. fig. 7). In 
Spergula and Sagina the capsule- walls and the outer parts of the 
dissepiments have risen decidedly, and the inner parts of the dis- 
sepiments have barely risen above the central elevation when the 
first ovules appear on its upper part (Pl. XXXIII. fig. 12). In 
Spergula four ovules are formed in each loeulus. The walls of 
the capsule grow up rapidly and close over to form the roof; the 
upper part of the capsule is unilocular, owing to the dissepiments 
not meeting above (Pl. XX XIII. fig. 14). 
The development of the capsule of Arenaria verna, A. serpylli- 
folia, and A. trinervia is very much like that of Sagina apetala. 
In these species the three pockets formed by the young carpels 
are narrow in a radial direction. The central elevation, on the 
first appearance of the carpellary prominences, is higher in pro- 
portion to its breadth than in Sagina; although the walls of the 
young capsule soon reach its apex, they do not rise above it till 
after the appearance of the first ovules on its upper sides 
(Pl. XXXV. figs. 5 & 6). In Arenaria serpyllifolia six ovules 
are formed in each loculus; in A. £rinervia five ovules: in this 
latter species at the base of each seed is an aril formed of from 
twenty to thirty large elongated, thick-walled, transparent cells. 
In the flower of Stellaria media, after the formation of the sta- 
minal whorls, the central elevation is almost hemispherical. The 
carpels first arise around its base as three blunt prominences, 
and these grow to the form of narrow pockets: the dissepiments 
soon rise almost to the apex of the central elevation as three low 
ridges of tissue ; the capsule-walls have only risen to about two 
thirds of its height when the first ovules begin to appear on its 
upper part between the dissepiments (Pl. XXXV. fig. 7). In 
this species, when the flower opens, the dissepiments are detached 
from the lateral walls of the capsule, they have grown broad, and 
are of very loose tissue; the micropyles of the campylotropous . 
ovules rest on, or are turned towards them, suggesting the idea 
that these present the course along which the pollen-tubes may 
be directed to the micropyles. Four ovules are formed in each 
loculus. 
