226 STRUCTURE AND LIFE HISTORIES 
may be very greatly reduced, as in Sphagnum; or the 
spore-case may not appear as a clearly denned organ, 
but may appear to merge very gradually into the stalk, as 
in Anthoceros. In liverworts the spore-case never opens 
by a lid or operculum, as is universally the case in mosses, 
but always by valves, formed by longitudinal splittings 
of the sporangial walls. Elaters may or may not occur in 
liverworts, but never occur in mosses. The sporogonium 
of liverworts and mosses never possesses a leafy stem, and 
never possesses true roots; only one case (that of the moss, 
Eriopus remotifolius) has ever been reported where the 
sporogonium produces rhizoids from its basal end. To 
compare the simple sporogonium of liverworts and mosses 
with the leafy plant of the true ferns, would be quite super- 
fluous. It should, however, be pointed out that the sporo- 
phyte of liverworts and mosses lives always, throughout its 
life, as a parasite on the gametophyte, while the sporophy te 
of ferns always becomes established, sooner or later, as an 
independent plant. Except for the very simple columella 
of Anthoceros and the central strand in the seta of mosses, 
nothing approaching a true vascular bundle occurs in the 
liverworts and mosses; while, as stated before, the well- 
developed nbro-vascular system of the ferns has caused 
them to be known as vascular cryptogams. 
