350 Bower . — The comparative examination of the 
young wings towards the base of the leaf, so also here the 
structure of the wing at the base of the frond is more 
complicated than above. If transverse sections be cut from 
a young frond of Scolopendrium near to its base, the internal 
structure of the wings does not admit of their tissues being 
referred in origin to marginal cells similar to those typically 
found in the upper part of the leaf: they appear to correspond 
rather in structure and development to that more robust form 
to be presently described as typical for the Osmundaceae and 
Marattiaceae, in which no single series of marginal cells is 
present. Similar results are to be obtained from Asplenium 
nidus , Aspidium Filix-mas , etc.; in fact, it seems to be a 
common character among the Polypodiaceae that the wings 
are more bulky towards the base of the frond, and that their 
construction is there on a more complex type. There is thus, 
roughly speaking, a proportion between the greater bulk of the 
phyllopodium and that of the wings towards the base of the 
leaf, while both are less bulky and simpler in construction 
above. This corresponds to similar observations above noted 
in the leaf of Trichomanes reniforme . 
Examination of the leaves of Amphicosmia (Hemitelid) 
Walkerae , Hk., shows that the type of the Polypodiaceae 
holds also for this representative of the Cyatheaceae. In the 
mature leaves of this plant the wings are but slightly indi- 
cated towards the base, appearing there as discontinuous 
longitudinal streaks, and in the young state a definite series 
of marginal cells is not to be recognised there ; but trans- 
verse sections of the upper parts of the pinnae and pinnules 
show the marginal series of cells clearly defined, and with 
that regular alternate segmentation above described for the 
Polypodiaceae. 
In connection with the c filmy ’ development of Ferns an 
interesting question arises as to the nature of those strange 
growths called Aphlebiae , which are found attached to the 
base of the leaf of Hemitelia ( Alsophila ) capensis 1 : such 
1 I owe it to Prof. Bayley Balfour that my attention was drawn to this Fern, 
and it was on specimens supplied by him from the Edinburgh Botanic Garden 
