380 



MUSCJNEM. 



of true Mosses ; but there occur, besides the ordinary (large) spores, also smaller spores 

 in special smaller sporogonia, which owe their origin to a further division of the mother- 

 cells (cf. Fig. 258, B). The theca opens by the detachment as a lid of the upper seg- 

 ment of the wall of the spherical capsule, which is sometimes more strongly convex. 

 The calyptra, which closely surrounds the growing sporogonium as a fine envelope, is 

 ruptured irregularly. 



2. The AndresBacesB ^ are small cespitose Mosses which are very leafy and much 

 branched ; their very shortly stalked theca is elevated, as in Sphagnum, above the 

 perichaetium on a leafless pseudopodium. The long apiculate theca raises up the 

 calyptra in the form of a pointed cap, as in the true Mosses, while the short seta 

 remains buried in the vaginula. The body of the young sporogonium becomes differen- 

 tiated into a parietal tissue consisting of several layers which surrounds the simple layer 

 of the spore-mother-cells without any intermediate cavity, and a central mass of tissue, 

 the columella : in the same manner as in the Sphagnaceae, the layer of cells which 

 produces the spores is bell-shaped and closed above, the columella terminating beneath 



Fig. 264. — Archidtunt phascoides ', A longitudinal section 

 of the young sporogonium, showing the mother-cell m of the 

 spores ; B longitudinal section through the young sporogonium 

 with its calyptra and vaginula.yfoot of the sporogonium, -w wall 

 of the theca, i intercellular space, c columella, h hollow out of 

 ■which the spore-mother-cells have fallen, v vaginula, st stem, 

 b leaves, a neck of the archegonium. After Hofmeister (Xzoo). 



Fig. Q&^.—Archidmm phascoides; 

 longitudinal section through a nearly 

 ripe sporogonium, w its wall, sp its 

 spores, V the vaginula, b leaves of the 

 stem, St base (foot) of the sporogonium. 

 After Hofmeister (X 200). 



it. The ripe theca does not opeil by an operculum, but by four longitudinal slits at 

 the sides ; four valves are thus formed united at the apex and at the base, which are 

 closed in damp, but open in dry weather. 



3. The PhascaceflB are small Mosses, the short stems remaining attached to the 

 protonema until the spores are ripe ; they may be considered as the lowest form of the 

 following group, to which the genus Phascum forms the transition. They are, however, 

 all distinguished by their theca not opening by an operculum, but allowing the escape 

 of the spores only by its decay. While in the genera Phascum and Ephemerum"^ the 

 internal differentiation of the theca corresponds essentially to that of true Mosses, 

 although more simple, the genus Archidium displays a more considerable deviation, 

 and as an interesting transitional form may be examined a little more closely ^. The 



^ J. Kiihn, Zur Entwickelungsgeschichte der Andreaeaceen. Leipzig 1870. 

 ^ J. Miiller, in Jahrbuch fiir. wiss. Bot. 1867, vol. VI. p. 237. 



^ Hofmeister, in Bericht der konigl. Sachsich. Gesellsch. der Wiss. 1854, April 22. [See also 

 Leitgeb, Das Sporogon von Archidium, Sitzber. d. Wien. Akad. 1879. He shows that the mother- 



