IO 
Tcinsley and Lulham. 
types, as he has remarked, the general outline of this is kept, though 
the plate is not continuous, but is resolved into a number of distinct 
strands. 
The degree of complication of the curve varies very greatly in 
the species under consideration. Let us first take the elaborate 
petiolar system represented in Fig. 34, since this gives us the 
closest resemblance to Pteris incisa var. integrifolia. 
Fig. 13 . 
Fig. 13. Pteris aquilina. Diagram of node seen from ventral side, rh., 
rhizome, pet., petiole, sh. b., shoot-bud. The numbers refer to the 
planes of section of the figures so numbered. 
Fig. 34 shews the transverse section of the petiole just above 
the departure of the lateral branch (see Fig. 13). The petiolar strands 
are arranged on a figure of the general outline of an O with the top 
(abaxial side, bottom in Fig. 34, p. 12) pushed in. The resemblance 
to Fig. 12 is very close, the only difference in the outline of the figure 
being the absence of the incurvings of the free margins in Fig. 34. 
Furthermore the origin of the strands of the lateral shoot from 
those of the petiole, as shewn in Figs. 26—33 is strikingly similar 
to that of Pteris incisa var. integrifolia, if allowance be made for 
the fact that the internodal vascular system of Pteris aquilina con¬ 
sists of two circles of strands, while that of Pteris incisa is a simple 
solenostele. Compare Fig. 26 with Fig. 8, and Fig. 31 with Fig. 9. 
