144 STRUCTURAL BOTANY 



way from any part of the plant from rhizoids (see 

 Fig. 59) or stem, or detached leaves, or even from the 

 fruit itself. In the latter case we have production of 

 the sexual direct from the asexual generation, affording, 

 in fact, an instance of apospory, such as sometimes 

 occurs in the Ferns (see p. 76). The production of 

 protonema provides the plant with a most abundant 

 means of vegetative propagation, for every growth of 

 protonema is capable of giving rise to a number of 

 Moss plants. Many Mosses produce special vegetative 

 buds either on their stems or rhizoids (Fig. 59, A, 5), 

 or throw off certain of their leaves as organs of propa- 

 gation. In most cases, whatever be the nature of the 

 reproductive body, whether spore or bud, it begins by 

 forming protonema, from which the leafy plants arise 

 at a later stage. This insertion of a filamentous stage 

 of growth in 'the life-cycle, before the production of the 

 typical form of oophyte, is very characteristic of the 

 true Mosses ; in the Liverworts, the protonema is on 

 the^whole much less developed. It may be compared 

 with the early filamentous stage of a Fern-prothallus, 

 with which it is quite homologous. 



SUMMARY 



If we now briefly sum up the characteristic points in 

 the life-history of the true Mosses, we see that both 

 generations are decidedly more highly organised than in 

 the Liverworts. The oophyte is here constantly developed 

 as a leafy stem, quite comparable to that of the higher 

 plants, though occupying a different place in the life- 

 history. We find at the same time a considerable 

 degree of anatomical complexity, corresponding to the 



