MOSSES AND LIVERWORTS 



109 



the sporophyte in Riccia is very simple, recalling that 

 of Coleochaete (Fig. 10, C) among the algse, 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 HepaticEe). — A, young em- 

 bryo-sporophyte ol Targionia ; i, ii, the first division walls in the fertil- 

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

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

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

 sporophyte of Sphserocarpus ; 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 OEdogonium. Here, however, 

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

 minates at once. It first divides by a transverse wall 



