BRYALES 
and the columella is in <Amdreaea a very 
irregular one (Fig. 135). Further, in Avchidium, 
which some writers put in close relation to 
Andreaea, any cell derived from the endo- 
theclum may apparently become a_ spore- 
mother-cell. 
It is thus seen that though Sphagnum and 
"Andreaea have certain apparent characters of 
the sporogonium in common, their segmen- 
tation is essentially different, and the dome- 
shaped archesporium is produced in different 
ways in the two. It remains doubtful there- 
fore how far the similarities indicate a real 
affinity. In any case the relation of the 
Andreaeales to the simpler Bryales is much 
nearer than to the Sphagnales, and it is in 
this direction that comparison of the sporo- 
gonia will bring the more interesting con- 
clusions concerning them. 
C. BRYALES. 
These include the vast majority of Mosses. 
In their sporophyte generation there is uni- 
formity of the general scheme, though 
considerable fluctuation in size, as well as 
in minor detail. Some of the smallest forms, 
which show irregular opening of the capsule 
on maturity, are classed as the Cleistocarpae ; 
the more elaborate forms, which dehisce 
transversely, setting free an operculum, are 
designated the Stegocarpae. The latter, as 
they represent the prevalent type in Mosses, 
will be taken first, while the Cleistocarpic 
forms being taken later, will then be better 
appreciated in their value for purposes of 
comparison. 
(a) Stegocarpae. ‘ 
The embryo of all these Mosses takes at 
an early stage the form of a more or less 
slender, but always simple spindle: any later 
deviations from this are of secondary origin. 
Its development from the zygote is first by 
277 
Fic. 135. 
Ceratodon purpureus. A, B, young 
embryo seen from points of view at 
right angles to one another. C=an 
older embryo; gg=outer limit of endo- 
thecium; s#s=outer spore-sac. (After 
Kienitz-Gerloff.) 
the appearance of a transverse basal wall, which is succeeded by oblique 
segmentations in the epibasal half: these appear alternately on opposite 
