2 0o Bower. — Some Normal and Abnormal 
long filaments, undergo segmentation, and assume the cha- 
racters of a branched protonema ; or again, such growths may 
occasionally be produced from the surface of the frond, 
especially in connection with the nerves (Fig. 28), but this 
origin from the surface is less common. Occasionally fila- 
mentous growths arise from the sporangium, and it is difficult 
at times to distinguish between the intra-sporangial germina- 
tion of spores and growths from the wall or annulus of the 
sporangium. In the case shown in Fig. 29, the latter origin 
seems to be the true one, since the central cavity is filled with 
an ill-defined brown mass, such as is seen in sporangia in 
which the development of spores is arrested ; thus it is 
probably an example of aposporous development of pro- 
tonema from cells of the annulus, following on sporal arrest. 
Sooner or later flattened expansions, one layer of cells in 
thickness, may be formed on these protonemal filaments. 
Secondly, flattened outgrowths may originate directly from 
the frond of the sporophyte without the intervention of pro- 
tonema. On old fronds it is not at all uncommon to find the 
tips of the pinnules produced into strap-shaped growths 
(Fig. 30), which assume an oblique or upright position, and 
are distinguished from the frond by the entire absence of the 
sharply-conical branched hairs, which are so characteristic of 
the sporophyte in this species, and by the want of any midrib 
with a vascular bundle 1 2 . At their upturned apices tufts of 
‘ sterigmata 5 2 may be seen, bearing gemmae. It will be shown 
1 In this plant it has at times been difficult to distinguish between the thin 
flattened prothalli and the thin lateral portions of the fronds which produce them, 
and resemble them closely in structure and arrangement of the cells. A constant 
character of the frond of the sporophyte in this species is the presence of branched 
hairs with sharp apices and thickened walls (Fig. 24) ; these differ essentially both 
in the mode of branching and in the sharpness of their apex from the protonemal 
filaments or rhizoids, which are formed on the prothalli ; and the presence of these 
branched conical hairs may be taken as a diagnostic character of the sporophyte 
from the oophyte : without this mark the distinction of the two generations wou'd 
often be difficult, and especially so in the specimens of apogamy to be described 
later. 
2 The term ‘ sterigma’ has been adopted by Goebel ( 1 . c. p. 82) for the pedicels 
which bear the gemmae. 
