522 _ LIFE-HISTORIES 
whether it be a seaweed, a lichen, a liverwort, or one of the 
higher plants. In strictest botanical use it belongs only to 
about 5,000 species of small green plants which have pseudo- 
leaves usually arranged spirally on a pseudo-stem, and pro- 
duce spores in urn-like cases opening mostly by a lid. 
Fic. 343.—Horned-liverwort (Anthoceros levis, Horned-liverwort Family, 
Anthocerotacee). Plant ({) with three ‘‘fruits’’ (sporophytes). (Luers- 
sen.)—Rather common in moist soil. 
Fic. 344.—Horned-liverwort. A, branched thallus. 3B, thallus (44) cut 
vertically to show the antheridia (an), the pseudo-roots (w), and a 
colony of Nostoc (k) which sometimes lives in the interior of this plant. 
C, vertical section through tip of thallus (#32) showing beginnings of 
archegonia (ar). D, section through older part of thallus (#82), show- 
ing a fertilized archegonium in which the egg-cell has begun to divide. 
E, embryo of sporophyte showing shoot-part above and foot below. 
(Hofmeister.) 
True mosses resemble liverworts except in having a mostly erect 
gametophyte with pseudo-leaves spirally disposed about a pseudo- 
stem which supports a sporangium dehiscing by a lid and lacking ela- 
ters. These peculiarities are shown in the peat moss (Sphagnum, 
Figs. 227, 346-349) and the cord moss (Funaria, Figs. 350-356). 
The spores of Sphagnum (Fig. 346) germinate in water by send- 
ing out a branched thread which resembles a filamentous alga. 
Sooner or later this thread gives rise at several points to apical cells 
each of which by its frequent oblique divisions produces a pseudo- 
stem with pseudo-leaves. If, however, the spore falls upon moist 
earth, its germination is more like such a liverwort as Anthoceros 
or Marchantia, for the initial thread soon develops into a flat- 
lobed thallus, producing slender pseudo-roots below, and _ vertical 
