MOSSES. [ 433 ] 



(fig. 473), either on the same plant, or on a 



Fig. 473. 



Mnium arcticum. 



Antheridial inflorescence, 



Maorn. 25 diams. 



bears the 

 globular, 



diflFerent one from that which 

 arche2;ones. The antherids are 

 oval (fig. 471 ), or elongate membranous sacs 

 composed of cellular tissue, filled with mi- 

 nute cellules, which escape by the bursting 

 of the apex of the sac ; and these cellules 

 exhibit a fibre coiled in their interior, which 

 circulates rapidly, even before the expulsion 

 from the antherid, and after a time breaks 

 out of its cellule (fig. 472, and PL 32. fig. 33), 

 and moves rapidly round in the water under 

 the microscope (see Antheridia). The 

 antherids are generally accompanied by cel- 

 lular filaments which have received the name 

 of paraphyses ; no physiological office is 

 attributed to these, but the antherids are 

 regarded as male organs. 



The archegone of the Mosses (figs. 32, 33, 

 p. 60, 471), like that of the Hepaticaceae 

 (excepting Anthoceros), is a flask-shaped 

 cellular case, the epigone containing an em- 

 hryonal cell at the bottom of its cavity. This 

 embryonal cell becomes gradually developed 

 by cell-division into a conical body elevated 

 on a stalk, which at length tears away the 

 walls of the flask-shaped epigone by a cir- 

 cular fissure, and carries the upper jsart up- 

 wards as a hood, while the lower part re- 

 mains as a kind of collar round the base of 

 the stalk (figs.474,476); the latter is termed 

 the vaginule (fig. 477) ; the cap-like portion 

 carried upwards on the sporange is called 

 the calyptra (figs. 474-476). The sporange, 

 elevated more or less by the development of 

 its stalk {seta or peduncle), is gradually con- 

 verted by internal changes into a hollow urn- 

 like case, usually with a stalk-like column 

 (Columella) running up its centre (figs. 50, 

 p. 72, 479), the space between the central 

 column and the side walls becoming filled 

 with free spores, which are minute cells with 

 a double coat, the outer of which exhibits 

 elegant markings (see Spores). In some 

 cases this hollow case does not burst natu- 

 rally, but the spores escape by its decay 



MOSSES. 

 Fig. 474. Fig. 475. 



Fig. 476. 



Fig. 474. Coscinodon pulvinatus. Capsule enclosed in 

 the calj'ptra, with the vaginule below. 

 Magn. 10 diams. 



Fig. 475. Orthotrichmn Hutchinsii. Capsule covered by 

 the calj'ptra, with vaginule below. Magn. 

 10 diams. 



Fig. 476. Ditto. Calyptra. Magn. 25 diams. 



Fig. 477. O. stramineum. Vaginule. Magn. 25 diams. 



(AsTOMUM, fig. 50). In the Andr^e^ 

 (fig. 11, p. 33) the sporange bursts by four 

 vertical slits, so as to be divided into four 

 valves, like the Jungermanniese, and there is 

 no column in the sporange here, but the valves 

 do not separate at their summits, and the 

 character of the leafy stem at once distin- 

 guishes these Mossesfrom those Hepaticacese. 

 The ordinaiy course, however, in the Mosses 

 is the formation of a horizontal slit near the 

 top of the sporange, so that the upper part 

 falls off" like a lid {operculum, fig. 483). 



The sporange of the Mosses exhibits a 

 very complex anatomical structure, which 



^ F 



