CHAPTER II 

 MUSCINAE (BRYOPHYTA) HEPATICAE MARCHANTIALES 



THE first division of the Archegoniatae, the Muscinese or 

 Bryophyta, comprises the three classes, Hepaticse or Liverworts, 

 the Musci or Mosses and the Anthocerotes. In these as a rule 

 the gametophyte is much more developed than the sporophyte, 

 and indeed in many forms the latter is very rarely met with. 

 They are plants of small size, ranging in size from about a milli- 

 metre in length to 30 centimetres or more. A few of them are 

 strictly aquatic, i. e., Riella and Ricciocarpus among the Hepat- 

 icae, and Fontinalis of the Mosses; but most of them are 

 terrestrial. A favourite position for many is the trunks of 

 trees or rocks. Many others grow upon the earth. They 

 vegetate only when supplied with abundant moisture, and 

 some forms are very quickly killed if allowed to become dry; 

 but those species which grow in exposed places may be com- 

 pletely dried up without suffering, and some of those that 

 inhabit countries where there are long dry periods may remain 

 in this condition for months without losing their vitality, 

 reviving immediately and resuming growth as soon as they are 

 supplied w r ith the requisite moisture. 



The germinating spores usually produce a more or less 

 well-marked "protonema," from which the gametophore arises 

 secondarily. The protonema sometimes is persistent and 

 forms a dense conferva-like growth, but more commonly it is 

 transient and disappears more or less completely after the 

 gametophore is formed. No absolute line, however, can be 

 drawn between protonema and gametophore, as the former 

 may arise secondarily from the latter, or even from the sporo- 

 phyte. With very few exceptions, e.g., Buxbaumia, the game- 

 tophyte of the Muscineae is abundantly supplied with chloro- 



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