106 EVOLUTION OF PLANTS 
simply lives long enough to produce the sexual organs 
and to nourish the embryo-sporophyte until it becomes 
self-supporting. 
THE Liverworts (Hepatice) 
Like the Confervacee among the green alge, the 
Liverworts seem to represent a low generalized assem- 
blage of plants showing 
affinities with several 
other groups, and, in-. 
deed, they probably rep- 
resent the ancestral forms 
from which have arisen 
all the higher plants. 
While the lower Hepatice 
are but little more com- 
plicated than some of the 
Confervacez, others show 
a considerable degree of 
differentiation of the ga- 
d metophyte. The latter, 
Fre ae frepatiee)- Riccla gy the in the simplest cases (Fig. 
very small sporophyte; B, Cono- 27, A, C), is a small flat 
cephalus, st, stomata; C, Metz- 
geria; D, Blasia, a liverwort which 
shows the first formation of leaf- body or thallus composed 
like organs, 1; E, Lejeunia, afoli- of almost uniform green 
ose liverwort with definite stem ‘ 
and three rows of leaves, ee cells, the whole fastened 
d i ,» and small ventral “ 
er eas to the ground by numerous 
delicate hairs or rhizoids. 
This thallus grows by the divisions of a definite apical 
cell, which differs in different genera, or even in differ- 
ent. species of the same genus. 
