MOSSES AND LIVERWORTS 111 
note that in its earlier stages it is much simpler than 
the mature gametophyte, but closely resembles the fully 
developed thallus of certain Hepaticee whose sporo- 
phyte is much more highly developed than that of 
Riccia. 
In all the other liverworts the sporophyte shows a 
certain amount of vegetative tissue, only a portion being 
devoted to the formation of spores. The first step in 
this separation of sporogenous and sterile tissue is the 
division of the fertilized egg into two cells by a trans- 
verse wall, the upper part developing into the spore- 
bearing portion or “capsule,” the lower giving rise to 
an organ of absorption, the “ foot” (Fig. 28, O, f), and 
usually an intermediate region, which forms a stalk or 
pedicel which elongates at maturity, and causes the 
sporophyte to rupture the archegonium-venter, and thus 
facilitates the scattering of the spores. In most of the 
Hepatice the vegetative tissue develops but little chloro- 
phyll, and the growth of the sporophyte is mainly at the 
expense of the gametophyte, from which, by means of the 
foot, it absorbs nourishment very much as a parasitic 
fungus does from its host. In all of the Hepatice, except 
‘Riccia and one or two closely related genera, only a 
part of the sporogenous tissue or archesporium pro- 
duces perfect spores. The others either remain unde- 
veloped and serve to nourish the growing spores 
produced from the other cells, or more commonly they 
remain undivided and form peculiar cells known as 
“elaters.” These elongate and develop upon the inner 
face of the cell-wall thickened spiral bands which, when 
fully developed, are strongly hygroscopic, and by their 
movements, induced by changes in moisture after the 
