376 ORGANOGRAPHY. 



perigone, in which case such Mosses have been termed her- 

 maphrodile. More frequently however, they are in different 

 perigones, and then both kinds of reproductive organs may 

 occur on the same plant, or on separate plants ; in the former 

 case we apply the term monoecious, in the latter dioecious (^figs. 

 154 and 155). 



The antheridium is a somewhat elliptical, more or less rounded 

 or elongated cellular sac (Jig. 799), Avhich is filled at maturity 

 with a number of minute cells, c, which have been termed 

 zootheccB ; in each of these there is a single spiral phytozoon or 

 spermatozoid. The antheridium opens by an irregular perfora- 

 tion at its apex, and thus discharges the cells with their phy- 

 tozoa. Among the antheridia there are generally to be found, 

 slender, cellular, jointed threads (fig, 799, />), calledi parapht/ses, 

 which are probably nothing more than abortive antheridia, 

 as they appear to perform no special function. 



The archegonia, like the antheridia, are often surrounded by 

 filamentous cellular bodies, called paraphyses, which appear to be 

 in this case abortive archegonia {fig. 800). The archegonium is 

 a flask-shaped cellular body with a long neck, the whole some- 

 what resembling an ovary with its style and stigma. The neck 

 is perforated by a canal which leads into a cavity, at the bottom 

 of which is a single cell, called the germ or embryonal-cell. The 

 case of the archegonium is called the epigone. After fcrtihzation 

 this embryonal cell enlarges and is elevated on a stalk, and as 

 it grows upwards it bursts the epigone, and carries one portion 

 of it upwards as a kind of hood, while the other portion remains 

 below as a sort of sheath round the stalk. The central portion 

 formed by the development of the embr}H)nal cell, is called the 

 sporangium {fig. 801, sp), the stalk the seta {figs. 801, t, and 

 802, p), the hood the calypira {fig. 802 and 803, c), and the 

 sheath at the base, the vaginule {Jig. 801, v). 



The sporangium when fully formed, is a hollow urn-like case 

 {figs. 803 and 804), the centre of wliich is usually occupied by 

 a cellular axis, called the columella {fig. 807), and the s])ace be- 

 tween this axis and the walls of the sporangium is filled with 

 free spores, which are small cells with two coats and markings 

 resembling tliose of pollen-grains. The sporangium is either 

 indcliiscent ; or it opens by four vertical slits so as to form four 

 valves ; or more commonly by a transverse slit close to the apex 

 like transverse dehiscence in fruits, by whicli a kind of lid is 

 formed, called the operculum (figs. 804, o, and 805), this lid is 

 either persistent or deciduous. Tlie sporangium is sometimes 

 much dilated at the base, where it joins the seta ; this swelling 

 is called an apophysis, or, if "it only occurs on one side, a 

 struma. 



The wall of the sporangium is commonly described as con- 

 sisting of tlirce cellular layers, the outer of which forms the 

 operculum, and the iaucr two layers the peristomium. At the 



