38o 
MUSCINEM. 
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 AndreaeaceaB are small cespitose Mosses which are very leafy and much 
branched ; their very shortly stalked theca is elevated, as in Sphagnum, above the 
perichsetium 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. ■2&\.—Archidin7n phascoides ; A longitudinal section 
of the young sporogonium, showing the mother-cell vt of the 
spores ; R 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 (X 200). 
Fig. 26^.— Arc hidiU7n 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 open 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 PhascaeesB 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. Kühn, Zur Entwickelungsgeschichte der Andreseaceen, Leipzig 1S70. 
^ J. Müller, in Jahrbuch für, wiss. Bot. 1867, "^ol. VI. p. 237, 
^ Hofmeister, in Bericht der königl. Sächsich. Gesellsch. der Wiss. 1854, April 22. [See also 
Leitgeb, Das Sporogon von Archidium, Sitzber. d. Wien. Akad. 1879. He shows that the mother- 
