BRYALES 283 
Phascum: the sterilisation of the whole of the upper products of the 
endothecium at the narrow distal end of the fertile tract would interrupt 
the dome, and complete the columella, just as it is seen in Phascum. 
There is no inherent im- 
probability in this, but 
rather the reverse: for it 
would be only introducing 
one further step in sterili- 
sation. On such grounds 
YQ 
& 
? “SP 
the relation of the Phasca- ig = 
ceae to the Andreaeaceae A | eal 
ERY “sps 
would appear to be a near (sie 
ea mg) 
one. (A 
REZ OTH 
AEN 
Another simple Cleisto- 
carpic form which has not 
only been observed exter- 
nally, but also worked out 
developmentally, is /Vano- 
mitrium  tenerum. The 
small capsule has here a 
provision for dehiscence 
by the formation of a 
rudimentary annulus. The 
segmentation of the embryo 
begins on the plan of the 
Bryales (Fig. 140, 1.), and Fic. 139. 
there is as usual a differen- Phascum cuspidatum, Schreb. Schut. A =longitudinal section 
through a sporogonium after formation of the air-space; sf=arche- 
tiation of the endothecium sporium; sfs=spore-sac; gg=limits between amphithecium and 
and amphithecium (Fig. endothecium. #=transverse section of the same. (After Kienitz- 
" Gerloff.) 
140, 11.). The cells of the 
latter, after further division, become differentiated into an exiguous central 
columella, surrounded by relatively numerous and somewhat irregularly 
arranged spore-mother-cells (Fig. 140, 1v.): but as maturity approaches the 
columella disappears, its materials having served for nourishing the spores 
’ which fill the cavity of the capsule. 
The genus £phemerum is closely related with that of Manomitrium, 
from which it differs in the absence of any definite operculum: the 
condition of the columella is the same, but while it disappears at 
maturity in some species (Z. pafpillosum), in others it may still be seen 
in the mature capsule (Z. cvassinervium). The fact that stomata occur 
on the capsule-wall, though when ripe this is only a single layer in 
thickness, has its bearing on the question whether these simple Mosses 
are primitive or reduced forms. A systematic position is now assigned 
to them by many writers apart from other Cleistocarpic forms, in close 
relation to the Funariaceae. 
ae 
e, 
xf} 
ry Be 
V 
