CHAPTER YIII. 



BRYOPHYTA (Muscineae). 



I. HEPATICAE (Liverworts). II. MUSCI (Mosses). 



The Biyophyta are small plants, varying in size from 1 mm. 

 to about 30 cm., creeping or erect, having a thalloid, or more 

 usually a foliose body, consisting of a cell-mass exhibiting in 

 most cases a distinct internal differentiation. They possess no 

 true roots and no true vascular tissue. The life-history of the 

 members of the group is characterised by a well-marked and 

 definite alternation of generations. The Moss or Liverwort 

 plant is the sexual generation (gametophyte), and as a result 

 of the fertilisation of an egg-cell the asexual or spore-bearing 

 generation (sporophyte) is produced. The sporophyte never 

 exhibits a differentiation into stem and leaves. Asexual and 

 vegetative reproduction are effected by means of spores, bulbils, 

 or detached portions of the plant-body. Sexual reproduction 

 is by means of biciliate antherozoids produced in antheridia and 

 egg-cells formed singly in archegonia. 



In the Bryophytes the distinguishing characteristics are 

 more constant and well-defined than in the Thallophytes In 

 the former the plant nev'er consists of a single cell or coenocyte, 

 but is always multicellular, and exhibits in most cases a 

 definite physiological division of labour as expressed in the 

 histological differentiation of distinct tissue-systems. In the 

 Thallophytes there is no true alternation of generation in 

 the same sense as in the Mosses and Liverworts and in the 

 higher plants. In the Bryophytes the sexual reproduction has 

 reached a higher stage of development and a much greater 

 constancy as regards the nature of the reproductive organs. 



