CHAPTER VIII. 



BRYOPHYTA (Musoineae). 



I. HEPATICAB (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 sexiial 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 never 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. 



