582 
MR. F, O. BOWER ON THE COMPARATIVE MORPHOLOGY OF THE 
of a leaf or pinna of a Leptosporangiate Fern,* a number of cells dividing by peri- 
clinal and anticlinal walls. Thus the correspondence of structure with that of the 
Leptosporangiate Ferns may be dearly seen, though the whole is much more 
complicated. 
It will now be useful to compare the structure and development of the leaf of 
Angiopteris evecta as above described with that of the Leptosporangiate Ferns, and to 
note where the differences lie. It would be difficult to draw a comparison between the 
stipules of Angiopteris and any corresponding structure in the Ferns, were it not for 
the extension of the winged structure in Todea transversely across the face of the 
phyllopodiiun, so as to form the so-called “ axillary stipule.” As it is, however, this 
structure leads on as an obvious step to the stipular development in Angiopteris : the 
chief points of difference between them are (1) that the transverse portion of the 
structure appears in Angiopteris in the first instance, whereas in Todea ft is of 
comparatively late origin ; (2) that owing to the extreme shortness of the young 
phyllopodium in Angiopteris the longitudinal development of the basal wings is almost 
obliterated, while in Todea, and more clearly in Osmunda, it is very obvious, and may 
be traced upwards as continuous with the wings of the phyllopodium. By means of 
these intermediate forms supplied by the Osmundacece, we are, I th ink , justified in the 
conclusion that the peculiar stipular structures of the Marattiacece are merely modifi¬ 
cations of the winged development at the base of the leaf. 
In the arrangement of the meristem at the apex of the leaf of Angiopteris a decided 
advance is seen on that in the Osmundacece, and still more on that in the other 
Leptosporangiate Ferns. It was pointed out in the case of the leaf of the Osmundacece 
that the phyllopodium is, at least in the lower part where the three-sided cell was 
active, a structure which developed theoretically as well as practically in three 
dimensions of space. The same is the case in Angiopteris throughout the phyllopodium, 
in those cases at all events where it terminates abruptly. Further, the arrangement 
of the cells at the extreme apex is such, that the tissues cannot have been wholly 
derived from a single apical cell; there appears, on the contrary, to be a group of four 
apical cells : this is again a characteristic of a higher development, and it may be 
stated that in the arrangement of the meristem of the leaf, as also of the root, 
Angiopteris occupies an intermediate position between the Ferns and the plants of 
higher organisation. 
The pinnae and pinnules are here formed by monopodial branching ; no case of 
dichotomy has been observed. They arise as rounded masses of tissue, not as flattened 
structures. The wings which are developed upon them are not referable to a simple 
linear series of cells, but appear as a massive weal on each side of the pinnae or 
pinnule. In these points Angiopteris approaches the Cycadacece (cfi. infra) rather than 
the Ferns. 
Again, the pinnae are comparatively few, and in some cases, if not in all, the 
* Kny, l.c., taf. 7, fig. 7, M. Prantl, Hymenopliyllaceen, taf. 3, figs. 38-54. 
