112 
MORPHOLOGY 
The leaves at first have similar cells, but later there is a striking differentiation, 
certain of the cells becoming enlarged, hyaline, and perforate (figs. 244, 245). 
It is this abundance of hyaline cells and paucity of 
chlorophyll-containing colls that give a pallid look to the 
leaves. 
The axis of the leafy branch is differentiated into three 
regions: (i) a cortex of empty and perforate cells, like the 
hyaline cells of the leaf; (2) a cylinder of elongated cells 
with thick walls and small caliber (prosenchyma) ; and 
(3) a pithlike axis. 
There are no special structures for vegetative 
multiplication, but great masses of individuals are 
formed by the indefinite growth and branching 
above, accompanied by dying off below. 
FIG. 246. Sphag- Antheridium. The antheridia occur on special 
num: terminal cluster , , , / , , ,. 
of antheridial branches. densel 7 Ieaf 7 branches resembling small catkins 
(fig. 246). The leaves also usually differ in color 
from the ordinary leaves, and in the axil of each there is a solitary 
globular and long-stalked antheridium (fig. 247), just as in Porella 
(see p. 104). These antheridia 
develop by means of an apical 
cell with two cutting faces, the 
lower segments forming the 
stalk, and the upper segments 
forming the capsule, which is 
initiated by a series of peri- 
clinal walls that cut off the 
peripheral wall layer from a 
central spermatogenous group 
of cells. The antheridium 
opens by irregular lobes and 
discharges the two or three- 
coiled biciliate sperms. 
Archegonium. The arche- 
gonia occur at the apex of 
FIG. 247. Sphagnum: an antheridium aris- 
ing on branch between two leaves, showing the 
slender stalk and the globular head; the latter 
short branches, at the top of consisting of a wall (a single layer of cells) in- 
the plant (figs. 248, 249). vesting a mass of spermatogenous cells (in 
rr>. i 11 j j r which blocking can be distinguished). 
They are stalked and free, 
and develop as in the acrogynous Jungermanniales, the archegonium 
initials being segments of the apical cell, which itself finally becomes an 
