BKYOPHYTA 



103 



result of the development of the epibasal cell while the root is 

 represented by the body developed from the hypobasal one (see 

 vol. i. p. 11). The shoot is not differentiated morphologically, 

 always being a thallus and never bearing leaves. 



Besides the regular sexual reproduction, leading to antithetical 

 alternation of generations as described, the gametophyte may and 

 often does reproduce itself vegetatively, giving rise to a kind 

 of homologous alternation also. It rarely possesses the power of 

 forming gonidia, which we have seen to be so common among 



Fig. 861. 



Fh/. 861. Section of cup-shaped receptacle 

 of Marchantia, in ^vhich gemmae, a, are 



being developed. Fi<j. 862. A. Anlo- 



comnion androgijniim, showing gemma? 

 borne upon a long stalk. T,. Collection 

 of gemmee magnified. 



the Thallophytes. It often, however, produces gemma: upon some 

 part of its surface. These gemmae have a very varied distribution ; 

 in many Hepaticse they arise in cup-shaped receptacles upon the 

 upper surface {figs. 861 and 866) ; in others they are developed 

 upon the leaves ; in the Mosses a collection of them is sometimes 

 found upon a long stalk {Aulocomnioii) (fig. 862), or they may 

 occur upon the axis or on the root hairs. They are generally 

 flattened masses of cells, sometimes with definite growing points. 

 Most mosses can put out protonemal filaments from various parts 

 of their surface, which can develop new plants as did the original 

 protonema. Frequently branches are separated from the plant 

 by the dying away of the older tissue at their bases, and these 

 then become fresh plants. 



The Bryophyta include the two classes of the Hepaticae or 

 Liverworts and the Musci or true Mosses. 



