114 EVOLUTION OF PLANTS 
phases, the protonema and gametophore. The spore 
on germination produces a filamentous, or occasionally 
flat, alga-like growth, the protonema (Fig. 29, A, B, C, 
Bet pr ; 
Fic. 29 (Musci or True Mosses). — A, the 
liverwort-like protonema of a peat- 
moss (Sphagnum) with the leafy shoot, 
k, budding out from it; B, the fila- 
mentous protonema, pr, of a common 
moss (Funaria), with a very young 
leafy bud, k; C, an older stage of the 
same moss; D, the full-grown leafy 
gametophore, g, with the sporophyte, 
sp, still connected with it; ar, the re- 
mains of the archegonium carried up 
by the growth of the sporophyte. 
pr), and upon this 
arise special buds or 
branches which grow 
into leafy stems, the 
gametophores (Fig. 29, 
A, B,C, %), which bear 
the sexual organs.. The 
leaves of the gameto- 
phoric branches are 
commonly arranged 
spirally, and_ the 
branches seldom are 
flattened as in the 
foliose Hepatice. 
While there are cer- 
tain superficial resem- 
blances between the 
leafy stems of the 
mosses and foliose 
liverworts, there are 
differences which make 
it extremely improb- 
able that the former have been derived from the latter. 
The two forms are rather to be considered as parallel 
developments. In the Musci the structure of both leaves 
and stem is as a rule much more complex than in the 
Hepatice, and there is usually present a central strand 
of conducting tissue, quite wanting in both stem and 
leaf in the latter group. 
