Chapter IV 



63 



Nepenthes 



apical region. The median point and the Hd can thus draw upon a 

 richer vascular supply than the rest of the collar, which is entered 

 only by minor lateral veins, and thus overgrowth of the median region 

 may be stimulated." 



It may be answered (/) that the midrib vein enters and traverses 

 the spur to its tip (7 — 9, 10; Text fig. 2). (2) The Kd cannot be 

 regarded as the inner "curve-over" since the surface of the rim would 

 then be a part of the outer pitcher surface, which the histology of the 

 rim denies. The "inner curve-over" would then have to be sought as 

 an outgrowth of the under surface of the lid, and that does not exist, 

 (j) The vascular system of the lid, assuming its origin as a transverse 

 weal, along the pitcher edge (Troll), is as it should be. {4) The 

 anatomy of the spur shows it to be the organic apex of the leaf 



Fig. 2. — Nepenthes (various species). — i, Venation of lid and spur of a pitcher 

 I cm long; 2, of a pitcher 2 cm long; 3, of a pitcher 2.5 cm long; 4, of a full sized pitcher; 

 the veins (dotted lines) lie at a different level and more ventral to the rest (solid lines); 

 5, Section of pitcher wall just below the insertion of the spur in N. intermedia; 6, Section 

 through the spur of N. bicalcarata. 



(Hooker), this being supported by additional evidence here from 

 N. intermedia and N. bicalcarata (Text fig. 2). (5) The wide dis- 

 placement of Hd and spur in these and other species is not accounted 

 for. 



Histology of the peristome or rim. — • If we examine into the minute 

 anatomy of the hard, glossy surface tissue of the peristome we find 

 that it is composed of straight rows of cells, running across following 

 the transverse curve. In each row the cells overlap very much, in one 

 direction, the tapering tail of one cell overlapping the next and forming 

 a sharp ridge along it {8 — 7). The rows being straight, the cells 

 not imbricated as in the other pitcher plants, the ridges of successive 

 cells overlap the one over the other, to form a single sharp ridge, 

 about 0.017 mm. from its parallel neighbor. The general surface is also 

 formed into sulci separated by sharp secondary ridges about 0.17 mm. 



