18 J. M. Macfarlane. — Nepenthaceae. 



last, and is abundantly traversed by irregulär intercellular spaces. Many of its cells 

 contain crystals. Spiral cells ramify through the palisade layer, but are more abundant 

 in tbe loose layer. The vascular bundles (/") run beneath the junction of these two 

 zones. Each bündle is ensheathed by a fibrous sclerenchyma ring, and has the normal 

 bifacial arrangement. 



The histology of the tendril does not differ fundamentally from that of the petiole. 

 Its epidermis, cortex, and pith tissues are quite similar. The vascular bundles are 

 united into a ring, even more perfectly than in the petiole, by a zone of sclerenchyma. 

 The normal bundles that are thus connected, tend in nearly all cases to show bifacial 

 arrangement, even though the tendril may be cylindrical [N. ampullaria, N. maxima, 

 N. phyllamphora etc.). But in a few cases the bundles of the upper or ventral region 

 of the tendril may be inverted, when the xylem faces internally the phloem externallv 

 (N. Veitchii etc.), and so a close approximation to stem structure occurs. A set of 

 accessory pith bundles is even more perfectly developed than in the stem or petiole. 

 These are relatively of large size, even in such thin tendrils as those of N. phyllam- 

 phora and N. graeilis. With the exception of the dorsal median one, which is in 

 contact with the sclerenchyma ring, all are embedded in the pith. In most cases also 

 the xylem is ventrally, and the phloem is dorsally placed. 



As might be expected from its morphological relation, the general histology of the 

 outer wall of the pitcher and of the mesophyll substance broadly agrees with that of 

 the basal lamina. The corrugated surface of the peristome consists of highly cuticu- 

 larized epidermal cells arranged in radial rows, and neatly fitting into each other by 

 oblique walls. The surface of each cell is delicately striated radially, while the end 

 of the cell that is toward the mouth of the pitcher may slightly overlap the adjacent 

 end of the next cell within. These smooth glistening cells of the inwardly sloping part 

 form an insecure zone for insects that attempt to walk across it. Its action is aided 

 by the presence of a secretion from a series of remarkable nectar-glands, that are 

 deeply embedded in cavities of the incurved margin. These were first observed and 

 described by Gibbons-Hunt, and later were studied in detail by Dickson who named 

 them "marginal glands". They may attain to large size, and all excrete a juice that 

 has been proved by the writer to be particularly relished by insects. They are always 

 developed in the first seedling leaf, as a few (5 — 8) dark oval glands embedded in the 

 translucent margin. They increase in size and number as older pitchers form. Each 

 fully developed gland is an oval [N. ampullaria, N. graeilis etc. Fig. 7 E) or elongated 

 cylindrical [N. Edwardsiana, N. khasiana Fig. lF, N. phyllamphora) mass of cells. 

 Each originates as a central patch of epidermal cells that is carried inward by invagi- 

 nation of a circular area of the peristome margin. This patch swells out in the centie 

 of the depression, as an oval protruding body, while internally it continues to grow into 

 the substance of the peristome. When the gland has reached maturity the greater 

 part of its tissue is embedded in the mesophyll of the margin, while its free mamillar 

 extremity protrudes into the depression or canal of the margin, that acts as a lumen 

 for the discharge of the neetar secretion. Each gland is surrounded by a circle of 

 bundles, derived by Splitting of a single bündle that runs toward the gland from the 

 veins of the pitcher System (Fig. SÄ). These bundles Surround the limiting membrane 

 of the glands, and doubtless supply the glands with their secretion substance. They 

 are of smallest size in N. graeilis, N. Reinwardtiana and N. tentaculata, of medium 

 size in N. maxima, N. sanguinea and N. ventricosa, are long and cylindrical in N. 

 khasiana and N. phyllamphora, but the largest are those of N. Edwardsiana, which 

 may measure 6 — 8 mm X < — 1,5 mm. Their position is indicated, round the simple 

 margin of the pitcher in N. Lcnvii, by the minute apertures seen in the middle of 

 small papillae (Fig. \ 9). These apertures lead into cavities whose embedded glands are 

 elliptic and blunt. In iV. eehinostoma each is sunk in a depression at the tip of each 

 isolated tooth, and is oval in shape (Fig. 7 G). Though an abundant secretion is rarely 

 poured out by them, the writer has had frequent and convincing proof that it is greatly 



