650 GENERAL COMPARISON OF THE FILICALES 
either case are the same in nature and relative position, though they 
differ in their relation to the prothallus, and the foot is less fully 
developed in the Marattiaceae. 
It does not appear that the facts of the primary embryology have any 
very direct bearing on the present problem. It is interesting, however, 
to note that the axis is vertical 
from the first in the Marattiaceae, 
as it is also in most other Pterido- 
phytes, and this may be held to 
be the more primitive state for 
Ferns: the prone position char- 
acteristic of the Leptosporangiate 
Ferns is exceptional among Pteri- 
dophytes at large, and is probably 
derivative. 
A comparative study of the 
meristems which carry on the 
continued embryogeny of the Ferns 
has brought interesting results.} 
Examination of the apical regions 
of axis, leaf, and root indicates 
that in all of these parts the 
Marattiaceae show a _ relatively 
complex state, the whole part 
being referable in origin as a rule 
to a group of some three or four 
initial cells, usually of prismatic 
form. It has also been seen in 
them, in sections of the thick 
marginal wings of the leaf, that 
at least two and possibly more 
BiG a cells appear as initials. In the 
Az=apex of stem of Angiopteris evecta, seen from typical Leptosporangiate Ferns a 
above ; apparently there are four initials (7, +). x83. 
B=apex of stem of Osrzunda regalis, seen from above, single initial cell of conical form 
with initial cell (x) of regular form and segmentation ; 
per ha ala (2) shows. also a three-sided is present at the apex of stem, 
leaf, and root: and in the case 
of the wings of the leaf there is a single marginal series, so that in any 
transverse section only one initial appears. A similar examination of the 
Osmundaceae shows that structurally they hold an intermediate position: 
for while a single initial may be found in stem, leaf, and root, deviations 
from this are common. In the roots of Osmunda and Todea various 
1See Bower, Anxnals of Bot., iii, p. 305. Though this paper of 1889 was written 
from the point of view then current, that the Leptosporangiate Ferns were more primitive 
than the Eusporangiate, the facts are now equally available in their bearing on the contrary 
view at present held. (Compare Anz. of Bot., vol. v., p. 109.) 
