MOSSES AND LIVERWORTS 117 
(Fig. 80, A, a) is composed mainly of a spongy green 
tissue which is also present in the upper part of the 
capsule, surrounding the large air-spaces between the 
sporogenous __ tissue 
and the outer part 
of the capsule. This 
green tissue recalls 
the “mesophyll” or 
spongy green tissue 
in the leaves of the 
higher plants, and 
like the mesophyll 
communicates with 
the outside atmos- 
phere by stomata. In 
a few cases, this basal 
part of the capsule 
(apophysis) is a very 
much enlarged spe- 
cialorgan, comparable 
physiologically, al- 
though hardly struc- 
turally, with the 
leaves of higher 
plants. 
The . formation of 
spores is restricted to 
a very small part of 
Fic. 30 (Musci). — A, a longitudinal section 
through the upper part of the sporophyte 
of Funaria; a, the apophysis or en- 
larged basal part of the capsule, con- 
taining chlorophyll and with stomata 
in the epidermis; sp, the sporogenous 
tissue; 0, the operculum, or lid, which 
finally falls away and allows the escape 
of the spores; 7, the ring of cells where 
the lid o separates from the urn, or 
theca; B, cross-section of a young cap- 
sule, showing the position of the sporo- 
genous cells; C, a young stoma or 
breathing pore from the base of the 
capsule. The structure of the stoma is 
like that found upon the leaves of the 
higher plants. 
the sporophyte, the sporogenous tissue comprising but a 
single layer of cells forming a cylinder in the middle 
region of the capsule, and surrounding the central col- 
umella (B, sp). The upper part of the capsule usually 
