348 



BOTANY. 



flask-shaped body ; this in its first state is composed of a 

 layer of cells surrounding and enclosing an axial row of 

 cells, but by the change of most of the latter into mucilage, 

 and their consequent solution, the structure becomes tubular 

 above. The lower cell of the axial row is the germ-cell {A, 

 Fig. 234 ; o, and e, e, e, Fig, 235) ; it is a rounded naked 

 mass of granular protoplasm. In Antlioceros the archego- 

 nium is very simple; a row of cells perpendicular to the 



surface of the 

 thallus becomes 

 filled with proto- 

 plasm ; the low- 

 er develops into 

 a germ-cell, and 

 the others dis- 

 solve, forming 

 thus a tubular 

 opening to the 

 germ-cell. 



454. — After 

 fertilization the 

 germ-cell divides 

 successively in 

 several direc- 

 tions, giving rise 

 to a tissue, which 

 undergoes difEer- 



Fig. 236. — Anthoaeros Ja',m9. ^ff, thp jronns: sporogonium ent mOulnCa- 



cut vertically ; X. the invulucre, wiiiciria a portion of the -fi^^a .*« +Vio rli-f 



thallus developed so as to form a kintl of slieath ; c, c, the i-ious ill uiiB uii- 



coliimella ; s, the spores, x 150. — Alter Holmeisier. ferent Orders but 



which becomes in every case a sporogonium (called in descrip- 

 tive works a capsule) of some Idnd. In Riccia it is a simple 

 globular case filled with spores (B, Fig. 234, sg) ; in Antlioce- 

 ros it is an elongated body, with a single circular layer of 

 spores (Fig. 236), while in other cases its structure is^ quite 

 complex. In Marchantia, the sporogonium, when mature, is 

 a short-stalked, rounded body, filled with spores and radially 

 placed thin-walled cells, the elaters, each of which contains 

 one or more spiral fibres {IX., Fig. 235, and Fig. 240) ; it is 



