330 



PART III. THE CLASSIFICATION OF PLANTS. 



to the capsule. The hypobasal cell gives rise to the foot, which is 

 well-developed in the lower forms of both Hepaticae and Musci, 

 but is rudimentary in the higher. The foot, as stated on page 14, 

 is essentially an embryonic organ ; but it persists, acting, when 

 sufficiently developed, as the organ of absorption and attachment, 

 throughout the life of the Moss-sporophyte, because the sporo- 

 phyte, since it does not become free and independent, does not 

 altogether develope beyond the embryonic stage. In most forms 

 the epibasal half of the oospore also gives rise to a longer or shorter 

 stalk, the seta, by the elongation of which the capsule is raised up 

 out of the calyptra. In those Hepaticse which have a seta, its 

 elongation, and the consequent rupture of the calyptra, takes place 

 suddenly when the capsule is already mature and the spores fully 



FIG. 238. Comparative morphology of the sporopronium in the Bryophyta : diagram- 

 matic transverse sections of the young capsule. A Sphaerocarpus (typical Liverwort) ; B 

 Ceratodon (typical Moss) ; C Anthoceros (aberrant Liverwort). E Endothecium : g-g 

 primary divisions (quadrant and octant walls) ; s (shaded) archesporium ; C columella. 

 (A and C after Leitgeb ; B after Kienitz-Gerloff.) 



developed; in the Musci its elongation is gradual, whilst *the 

 capsule is still rudimentary, and the rupture of the calyptra takes 

 place relatively early. In the Hepaticae and some Musci (Sphag- 

 naceae, Archidium, Phascum, Ephemerum) the whole of the 

 raptured calyptra remains as a sheath, the vaginula, round the 

 base of the seta : but in the higher Musci (Andreaeaceae, most 

 Bryineae) the calyptra is ruptured transversely into an upper and 

 a lower half ; the latter constitutes the vaginula, whereas the 

 former is carried up as a cap on the top of the capsule. In some 

 forms, where' the true hypobasal foot is rudimentary (some Junger- 

 manniaceae and Bryineae) and is functionless, the base of the seta 



