MUSCI, 
361 
CLASS VI. 
M U S C P. 
The spore produces a conferva-like thallus, the Protonema, from which the 
leaf-bearing Moss arises by lateral branching with differentiation into stem and 
leaf. On this plant the sexual organs are formed; from the fertilised oosphere 
proceeds the sporogonium, in which the spores are formed from a small portion 
of the inner tissue. 
The Protonema arises, in the typical Mosses, as a tubular bulging of the 
endospore, which elongates indefinitely by apical growth and becomes septate, the 
septa being oblique. The cells do not undergo any intercalary divisions, but form 
branches immediately behind the septa; these branches also become septate, and 
usually show a limited apical growth ; they may, in turn, produce ramifications 
of a higher order. The part of the endospore which lies opposite the germinating 
filament may develope into a hyaline rhizoid, which penetrates into the ground. 
The cell-walls of the protonema-filaments are at first colourless, but as the primary 
axes He upon the ground or even penetrate into it, their cell-walls assume a brown 
colour, while the cells above ground develope abundance of chlorophyll-granules ; 
and the protonema is hence nourished independently by assimilation ; it not only 
attains a considerable size in some genera, covering a surface of from one to several 
square inches like turf with its densely matted filaments, but its term of life may be 
regarded as unlimited. In most Mosses it altogether disappears after it has 
produced the leafy stems as lateral buds; but where these latter remain very small 
and have only a short term of life, as in the Phascaceae, Pottia, Physcomitrium, &c., 
the protonema still remains vigorous after it has produced the leafy plants, and 
when the sporogonium has already been developed upon them. In such cases 
all three stages of the cycle of development are present simultaneously in genetic 
connexion. The Sphagnaceae, Andreaeacese, and Tetraphidese differ from the typical 
^ W. P. Schimper, Recherches anat. et pliysiol, sur les Mousses (Strassburg 1848). — Lantzius- 
Beninga, Beiträge zur Kentniss des Baues der ausgewaciisenen Mooskapsel, insbesondere des Peri- 
stoms (with beautiful illustrations) in Nova A.cta Acad. Leopold. 1847. — Hofmeister, Vergleich. 
Untersuch. 1851. [On the Germination, Development, and Fructification of the Higher Cryptogamia, 
Ray Soc. 1862.] — Hofmeister, in Berichte der Kön. Sachs. Gesellsch. der Wissens. 1854. — Ditto, 
Entwickelung des Stengels der beblätterten Muscineen (Jahrb. für wissens. Bot. vol. IH), — Unger, 
Ueber den anat. Bau des Moosstammes (Sitzungsber. der Kais. Akad. der Wissens. Vienna, vol. 
XLHI. p. 497).— Karl Müller, Deutschlands Moose (Halle 1853). — Lorentz, Moosstudien (Leipzig 
1864). — Ditto, Grundlinien zu einer Vergleich. Anat. der Laubmoose (Jahrb. für v\dssen. Bot, vol. VI, 
and Flora 1867). — Leitgeb, Wachsthum des Stämmchens von Fontmalis antipyretica u. von Sphagnum ; 
sowie Entwickelung der Antheridien derselben (in Sitzungsber. der Kais. Akad. der W^issens. Vienna 
1868 and 1869). — Nägeli, Pflanzenphysiol. Untersuchungen, Heft I, p. 15. — Julius Kühn, Entwickel- 
ungsgeschichte der Andreasaceen (Leipzig 1870), (Mittheilungen aus dem Gesammtgebiet der Botanik 
von Schenk u. Luerssen, vol. I). — Janczewski, Ueber Entwickelung der Archegonien, Bot, Zeitg. 
1872. 
