296 



GENERAL BOTANY 



when the elastic seta allows the capsule to be swayed by the wind. 

 We see, therefore, how admirably the moss capsule is organized 

 to form and disseminate the spores which give rise to new moss 



plants. These spores are highly 

 protected cells, not unlike the zy- 

 gotes of Spirogyra in structure, 

 although their asexual method of 

 origin is quite different from the 

 latter, as we have seen. 



Under the proper conditions of 

 temperature and moisture the spores 

 germinate and form a mass of fila- 

 ments, which often coat wet banks 

 or flowerpots with a green coating 

 resembling closely some of the algse. 

 From these filaments new leafy 

 moss plants arise (Fig. 165), which 

 in turn form gametes and start the 

 cycle of a new generation. 



Life history. The life history of 

 the moss is identical with that of 

 Ricciocarpus except in the greater 

 complexity of the gametophyte and 

 sporophyte plants and in the details 

 of spore germination. In both cases the gametophyte and sporo- 

 phyte alternate in regular sequence in the life history, the game- 

 tophyte plant doing the work of photosynthesis and the bearing 

 of the reproductive organs, while the sporophyte lives parasiti- 

 cally on the gametophyte and produces the spores. 



FIG. 165. Protonema and young 

 moss plants 



Young plant of a moss attached 



to a protonema with reproductive 



buds (6) 



