Xeropliytic Adaptations of Bryophytes. 
1 53 
3, 4), Eurynchium myurum ; in others they are convolute—e.g., 
Barbnla convoluta (Fig. 1, 2), Dicrcinellct secunda —or involute, e.g., 
Dicranoiveisia, thus further protecting the young capsule ; or they 
are fringed, as in Dipliyscium foliosum (Fig. 1, 5) and Tlmidium 
tamariscinum , the interlacing threads assisting by means of capillarity 
in the acquisition and retention of moisture. 
The ripe sporogonium of the liverworts does not require so 
much protection as that of the mosses, since it is almost mature 
before the development of the seta, the rapid elongation of which 
can only occur during moist conditions. The capsule-wall is 
Fig. 1. Xerophytic Structures in Sporogonium of Mosses. 1, Grimmia 
apocarpa, showing curved seta ( s .), x 4 ; 2, Barbnla convoluta, showing perichaetial 
leaves (p. 1.) and ordinary leaves, x 16 (s., seta of capsule); 3, perichaetial leaf 
of Pleuridium alternifolium, x 16 ; 4, vegetative leaf of P. alternifolium, x 16; 
5, ciliated perichaetial leaf of Dipliyscium foliosum, x 16 ; 6, calyptra of Encalypta 
vulgaris, x 4 (s, seta) ; 7, hairy calyptra of Polytrichum piliferum, x 4 ; 8, immersed 
capsule of Physcomitrium pyriforme (most of the perichaetial leaves have been 
removed, only one being left), x 16; 9, papillose seta of Brachythecium rutabulum, 
x 160; 10, superficial stoma of Orthotrichum affine, x 320 ; 11, immersed stoma 
of 0. anomalum v. saxatilis , x 320. 
cuticularised and ringed fibres are sometimes present, but the seta 
is of a fragile and short-lived nature, quickly disappearing when 
the surroundings become drier. The capsule has no air-space, 
stomata, or columella, (except in the Authocerotales), the nutrition 
