276 BRYOPHYTA 
These undergo further sub-divisions to constitute an endothecium of four cells, 
and a many-celled amphithecium (Fig. 134 G). The hypobasal half, which 
has meanwhile undergone irregular divisions, together with the two lowest 
segments of the epibasal region remains sterile, and constitutes the short 
seta and enlarged foot. Three or four only of the upper segments are 
fertile, while the rest go to form the sterile apex of the capsule (Fig. 134 ). 
Fic. 134. 
Development of sporogonium of Audreaca. A =young embryo of A. crassinervia, 
Breh. B=A. petrophila, Ehrh. C=of A. crassinervvia, older. D=of A. sf., older still. 
£=optical longitudinal section of A. petrophila ; spr=archesporium. /=optical 
verse section of a young embryo; ss gment-walls ; 7x=radial walls ; a@a=first divisions 
of the quadrants. G=older stage; gg=‘‘ grund-quadrat.” A =older stage with division 
to form archesporium. /=archesporium differentiated. A°=archesporium divided into 
two layers ; asp=outer spore-sac ; col.=columella. (After Waldner.) / after C, Miiller- 
Berol. (From Engler and Prantl.) 
The archesporium is here, as in all other Mosses, derived from the endo- 
thecium: the peripheral cells which result from the segmentation of the 
endothecium, become densely granular, and give rise to spore-mother-cells, 
the internal cells form the columella (Fig. 134 &, J, K). It is not stated 
by Waldner how the archesporial dome is completed at its apex: probably 
it is by certain cells of the inner product of the endothecium, forming 
spore-mother-cells, in place of sterile cells of the columella. In this there 
would be no theoretical difficulty, for on the present theory all cells derived 
from the endothecium were at first potentially fertile cells; moreover, as 
bearing indirectly on this point, the internal limit between the archesporium 
