228 



PLANT LIFE. 



cells. Mixed with the spore-producing cells, however, are 

 many sterile cells, which become gradually elongated, and 



spin 



Fig. 230. Fig. 231. 



Fig. 230. — The sporophyte of a peat moss (Sphagnum acutifolium) with adjacent parts 

 of the gametophyte. The sporophyte consists of a capsule, sg, and a broad foot, sg'. At 

 the stage shown in B it is still completely enclosed in the tissues of the gametophyte, 

 viz., c, the enlarged ovary which forms the calyptra or hood, and ?>, the vaginule or 

 sheath surrounding the foot, ar is the neck of the ovary. (Compare fig. 331.) The 

 arc over the large-celled central tissue (columella) is the sporangium. />s, the false 

 stalk, produced by the gametophyte, which raises the sporophyte. In A, the calyptra 

 has broken, only a fragment remaining, exposing the capsule. d, the lid, by whose fall 

 the sporangium is exposed and the spores escape, ch, leaves of the gametophyte ; qs, 

 the false stalk. Compare figs. 67, 72, 73, in which the stalk is part of the sporophyte. 

 A magnified 13 diam.; />, 32 diam — After Schimper. 



Fig. 231. — Longitudinal section of the young capsule of a true moss (Bryum). s, spo- 

 rangium. At this stage the mother cells of the spores, s/>»i, have become free (only a 

 few are shown still enclosing the spores) ; sw, the wall of the sporangium, lined by 

 the remains of another layer of cells now disorganized ; c, the columella, of partly col- 

 lapsed cells ; is, intercellular space ; civ, wall of the capsule ; an, the annulus, a ring 

 of cells which pries off the lid, at whose edge they develop ; o t, the outer, m. the inner, 

 peristome, formed by the thickening of parts of the walls of certain rows of cells ; nt, 

 nutritive tissue, with chloroplasts and intercellular spaces. Magnified 25 diam.— Orig- 

 inal. 



