MOSSES AND LIVERWORTS 



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the sporophyte in Riccia is very simple, recalling that 

 of Coleochsete (Fig. 10, C) among the algae, and there 

 is no difficulty in understanding how a sporophyte of 

 the type of that in Riccia may have originated from 

 that of Coleochsete. 



FIG. 28 (Development of the sporophyte in Hepaticae). A, young em- 

 bryo-sporophyte of Targionia ; i, n, the first division walls in the fertil- 

 ized egg; B, longitudinal section of the young sporophyte of Riccia, in- 

 cluded within the archegonium, ar; all of the cells, except a single 

 peripheral layer, produce spores ; C, longitudinal section of the young 

 sporophyte of Sphaerocarpus ; only the upper part produces spores, the 

 lower half forming an organ of absorption, the foot, /; D, a similar 

 section of the embryo of Anthoceros ; the nucleated cells represent 

 the archesporium or sporogenous tissue ; E, cross-section of an older 

 sporophyte of Anthoceros, showing the small amount of sporogenous 

 tissue, sp; F, section through a spore-tetrad of Fossombronia longiseta; 

 only three of the four spores show ; G, a ripe spore of the same species ; 

 H, an elater. 



The first result of fertilization is the formation of a 

 cellulose membrane about the egg, which thus is trans- 

 formed into a spore directly comparable to the resting- 

 spore of such an alga as GEdogonium. Here, however, 

 instead of remaining at rest for a long period, it ger- 

 minates at once. It first divides by a transverse wall 



