MVSCI. 361 



CLASS VI. 

 MUSCP. 



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 lie 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, Andreasaceae, and Tetraphideae differ from the typical 



* W. P. Schimper, Recherches anat. et pliysiol. sur les Mousses (Strassburg 1848).— Lantzius- 

 Beninga, Beitrage zur Kentniss des Baues der ausgewachsenen Mooskapsel, insbesondere des Peri- 

 stoms (with beautiful illustrations) in Nova Acta Acad. Leopold. 1847. — Hofmeister, Vergleich. 

 Untersuch. 185 1. [On the Germination, Development, and Fructification of the Higher Cryptogamia, 

 Ray Soc. 1862,] — Hofmeister, in Berichte der Kon. Sachs. Gesellsch. der Wissens. 1854,— Ditto, 

 Entvvickelung des Stengels der beblatterten Muscineen (Jahrb. fiir wissens. Bot. vol. IH). — linger, 

 Ueber den anat. Bau des Moosstammes (Sitzungsber. der Kais. Akad. der Wissens. Vienna, vol. 

 XLIII. p. 497). — Karl Mllller, Deutschlands Moose (Halle 1853). — Lorentz, Moosstudien (Leipzig 

 1804).— Ditto, Grundlinien zu einer Vergleich. Anat. der Laubmoose (Jahrb. fiir wissen. Bot. vol. VI, 

 and Flora 1867). — Leitgeb, Wachsthum des Stammchens von Fontinalis andpyretica u. von Sphagnum; 

 sowie Entwickelung der Antheridien derselben (in Sitzungsber. der Kais. Akad. der Wissens. Vienna 

 1868 and 1869). — Nageli, Pflanzenphysiol. Untersuchungen, Heft I, p. 15. — Julius Kiihn, Entwickel- 

 ungsgeschichte der Andreseaceen (Leipzig 1870), (Mittheilungen aus dem Gesammtgebiet der Botanik 

 von Sahenk u. Luerssen, vol. I). — Janczewski, Ueber Entwickelung der Archegonien, Bot. Zeilg, 

 1872. 



