MTJSCINE/E. 



429 



either with the archegonia, or in 

 Fig. 498. 



cells) escape by the rupture of the sac of the antlieridium, and each of 

 them emits a 2-ciliated spiral spermatozoid (fig. 497, d). 



In the Mosses the antheridia are larger and more elongated and cylin- 

 drical sacs, not stalked (fig. 498, b) ; they are found in the axils of leaves, 

 sometimes scattered, but more frequently collected in axillary or terminal 

 bud-like structures (inflorescence), 

 a monoecious or dioecious condi- 

 tion. The antheridial sacs are 

 filled with a tissue which is 

 ultimately resolved into sperm- 

 cells, which are discharged by 

 the bursting of the sac (tig. 498, 

 6); and when these escape (tig. 

 498, c) they in their turn emit an 

 active, spirally twisted, 2-ciliated 

 spermatozoid (d). 



The antheridia and spermato- 

 zoids of Mosses may be readily 

 observed in Polytrichum com- 

 mune, the male plants of which 

 form their "flowers" (stellulce 

 masculines) abundantly on every 

 heath in. spring. 



The archegonia are very much 

 alike in Hepaticae and Musci, being 



" " rl r>allnlE>r naaA witVi a Antheridium, archegonium, &c. of Mosses : a, ver- 



d cellular cases, with a tical gection of arc ^ egonium with g erm - ce ii from' 



Phaseum cuppidatum, magn. 100 diam. ; 6, anthe- 

 ridium of Polytrichum commune, bursting to dis- 

 charge spermatozoids, magn. 25 diam. ; c, sperm- 

 cell and spermatozoid of the same, magn. 200 

 diam. ; d, spermatozoids of the same, magn. 400 

 diam. ; e, immature fruit of Phaseum bry aides 

 (vertical section), c, calyptra, v, vaginule, magn. 

 40 diam. 



When 



long neck (tig. 497, a, b ; fig. 498, 

 a), found generally several to- 

 gether, commonly at the ends of 

 shoots, surrounded by modified 

 leaves, which receive special 

 names (pp. 431, 433), forming a 

 kind of perianth. In Anthoceros 



the archegonium is formed in the substance of the thalloid stem, 

 mature the archegonia exhibit in their basal cavity a germ-corpuscle (fig. 

 497, b ; fig. 498, d), which is fertilized by the passage of spermatozoids 

 down the canal of the neck of the flask-shaped body. In any case this 

 corpuscle is converted into a cell in one of the archegonia of a flower, 

 the rest remaining barren (fig. 497, p p}. 



When the germinal cell is fertilized, it begins to grow by cell-division, 

 and forms a cellular body which causes the expansion of the original wall 

 of the archegonium (fig. 497, e). After a time, this wall gives way, in 

 the Mosses by a circumscissile dehiscence, so that the upper part is carried 

 upwards (fig. 498, e, c), afterwards becoming the calyptra of the sporo- 

 gonium (fig. 500), while the lower part (tig. 498, v) remains as the 

 vaginule (fig. 500, c). In the Hepaticae the sac of the archegonium is 

 usually ruptured in the upper part, and there is no cup-shaped calyptra 

 formed, the sac becoming ultimately the envelope, corresponding to the 

 vaginule of Mosses, here often called the epigone (p. 433, fig. 501 B, a). 



The central cellular body (tig. 497, e) undergoes very remarkable 

 changes : by degrees it exhibits different strata and regions, and in the 



