SHOOTS OF MOSSES. 



67 



correctly, since the formative forces in the class of Mosses tend neither to the 

 formation of wood, vascular bundles, and elastic fibres, nor to a great ex- 

 tension of the assimilating surface, the plants remain relatively small— their mass is 

 insignificant in comparison with the majority of the more highly organised plants. 

 Moreover, the most various metamorphoses may occur in the shoots of Mosses, as 

 in tliose of the vascular plants. They produce runners with small leaves, which 



Fig. f>^.—Catharinca undulata, a moss. From the creeping rooted rhizomes are developed 

 upright leafy shoots, the older of wliicli bear tlie long-stalked sporogonia (natural size ; after 

 Schimper). 



sooner or later become rooted again and form upright leaf shoots, or they produce 

 tubers, rhizomes, &c. ; these all very small, and of simple cell -structure. A 

 special peculiarity of the true Mosses, however, lies in the production of a system 

 of shoots consisting merely of cell -filaments, the so-called protonema ; which 

 possesses in all essential points the nature of a shoot, without developing the 

 typical perfection of the moss-shoot. From this protonema are developed, as 



