The Development of the Sorus and Sporangium and 
the Prothallus of Peranema cyatheoides, D. Don. 
BY 
R. C. DAVIE, M.A., B.Sc., 
Lecturer in Botany in the University of Edinburgh. 
With Plate III and two Figures in the Text. 
I N a paper in the Annals of Botany, vol. xxvi, 1912, it was suggested that 
Peranema cyatheoides , D. Don, occupied a position intermediate between 
the Cyatheaceae and the Aspidieae group of Polypodiaceae. Various 
features of the mature plant, including those of the vascular system and the 
sporangium, suggested a relationship with the species of N ephrodium and 
especially with N. Filix-mas , Rich. Developmental stages of the sorus and 
sporangium have since been studied in material grown in the Glasgow 
Botanic Garden and kindly forwarded to me by Professor F. O. Bower, 
F.R.S. Fresh spores were sent from India through the kindness of the 
Director of the Calcutta Botanic Garden, and young plants were reared from 
them by Mr. L. B. Stewart, Plant Propagator in the Royal Botanic Garden, 
Edinburgh. In the Edinburgh Garden there are now half a dozen strong 
and healthy plants of Peranema . I tender my thanks to the gentlemen to 
whose courtesy this result is due. 
Development of the Sorus. 
P'rom the earliest stages available it appears that the sorus is very soon 
after its appearance covered almost completely by the indusium (PL III, 
Fig. 1 ). This indusium is composed, in the main, of a single series of cells 
though near the highest point of its curve and near its tip there are two cell- 
layers. It forms a scale attached at one side along a semicircular line to the 
under surface of the leaf and bent over the top of the receptacle. At one 
point the receptacle is, for a width of three cells, uncovered by the indusium. 
Below this point are one or two cells continuous with the series forming the 
epidermis of the leaf and with walls thickened like those of the cells of the 
indusium (Fig. 1). This suggests the presence of a small second flap. Sec- 
tions through older sori confirm the suggestion, since in these a distinct small 
second flap or edge of a cup is present (Figs. 2 and 3). In Fig. 3 the further 
curving over of the main indusial flap is shown. This is still more accen- 
tuated in Fig. 4, where the commencement of an extension of the receptacle 
at right angles to the leaf-surface can be distinguished. The second flap 
[Annals of Botany, Vol. XXX. No. CXVII. January, 1916.] 
