LIFE HISTORY OF A MOSS 2OI 
foot, imbedded in the tissues below, and connected with 
the spore-case by a very short stalk (Figs. 143 and 145). 
184. The Sporophyte. It will have been recognized 
already that the simple structure just described, since it 
bears spores, is the sporophyte stage of Sphagnum. 1 
While the sporophyte is maturing, the apex of the female 
branch elongates, forming a leafless stalk, a half inch or 
more in length. This stalk is called the pseudopodium 
(false foot). The development of the pseudopodium, 
coincident with that of the sporophyte is very interest- 
ing, and the question at once naturally arises, as to how 
this correlation is brought about. No positive explana- 
tion has ever been given, but it seems probable that, as the 
sporophyte begins to develop, the cells of the foot excrete 
some substance which stimulates the cells in which it is 
imbedded to divide and enlarge, resulting finally in the 
formation of the pseudopodium. The advantage of the 
pseudopodium in facilitating the distribution of spores 
by raising the spore-case higher into the air and well 
above the perichaetial and other leaves, is obvious. 
The sporophyte of Sphagnum possesses no chlorophyll, 
and consequently does not elaborate any food, obtaining 
its entire supply from the sphagnum-plant by absorption 
through the foot. Numerous groups of stomatal guard- 
cells occur on the wall of the spore-case, but they have no 
slit between them no true stomata and are there- 
fore functionless. There are also, underneath the guard- 
cells, no intercellular spaces, such as are always associated 
with true stomata. The presence of these functionless 
stomata is thought by some botanists to indicate that the 
1 Such simply organized sporophytes are commonly called sporogonia 
(singular sporogonium). 
