14 J- M. Macfarlane. — Nepenthaceae. 



X. bicalcarata this tissue only begins to separate by tbe \ th — 1 2 th year. Finally as 

 tbe stem matures, rounded elements in the cylinder of spiral cells of the pericambium 

 become increasingly tbickened, tili tbe lumen of eacb element is greatly reduced or 

 almost obliterated (Fig. §Bh). Tbese elements are most abundant next tbe outer pbloem, 

 but are also scattered tbroughout tbe entire zone in some species. In X. ampul- 

 laria they form a diseonlinuous mass of greatly tbickened scleroid elements around 

 tbe pbloem. 



Tbe stem and brancbes of many species may be abundantly covered witb bairs 

 of diversified structure, but as tbese resemble leaf bairs, they will be treated of under 

 that heading. The nectar-glands of the axial parts however deserve special mention, 

 not least from their striking resemblance to simple animal glands. Fig. 1 A, is a sec- 

 tion of a gland from the stem of N. phyllamphora. The epidermis has become deeply 

 and sharply involuted. It has divided into three layers of gland tissue, of which the 

 surface layer is deeply columnar. This lines a lumen that is lenticular below, con- 

 stricted above, and that again widening, opens by a small circular oriflce that discharges 

 the sweet secretion. The three glandulär layers of cells contain rieh finely-granular 

 protoplasm. Beneath tbese are two layers of bead-shaped cells, which in position and 

 relation suggest resemblance to the membrana propria of animal glands. A vascular 

 bündle given off from one of- the accessory stem bundles ends in the base of the 

 gland. A similar vascular supply exists for all the glands of Xepenthes. The axial 

 glands attain their largest size in X. bicalcarata, where the glandulär tissue may even 

 undergo branching as seen in glands on the flower stalk. 



The Leaf. The vascular connection and the course of the bundles in the stem 

 and leaf, have been fully elueidated by Zacharias. The bundles that have bent out 

 from the main cylinder as leaf-trace bundles, run into the cortex, and after branching 

 and proeeeding for a distance through it ; they bend into the leaf-cushion as a double 

 set of bundles, an inner and an outer. The inner ones are few in number, are of 

 large size, and lie in part against, in part outside of the fibrous cortex ring. The 

 outer are small, numerous, more or less alternate with the inner, and run between 

 the inner bundles and the chlorophylloid cortex. Crossing and fusion oeeur between 

 them, but higher up where the leaf cushion is prolonged into the petiole, the large 

 inner bundles become mainly the strong upper or ventral bundles of the petiole, while 

 the smaller ones in part become the arched set of bundles of the dorsal surface. 

 Section of the middle or lower part of a petiole of X. phyllamphora, X. bicalcarata 

 or others, shows within the epidermis and chlorophylloid cortex, a ventral plate of 

 cortex sclerenchyma, that may or may not be continued round the petiole as a ring. 

 Embedded on the inner side of it are the vascular bundles, either isolated or grouped 

 into patches of 2 — 4, two such groups usually oecurring along the ventral angles of 

 the petiole. In N. Veitchii and others the cortex sclerenchyma is not continuous, but 

 sclerenchyma rings exist round the individual bundles. All of the bundles that make 

 up the plano-convex ring are oriented so that their xylem is toward the upper or 

 ventral, the phloem toward the lower or dorsal side. The cellular tissue enclosed 

 within the ring has one median dorsal (X. phyllamphora, N. bicalcarata) or several 

 ventral vascular bundles (X. Veitchii) embedded in it. Its cells also may or may not 

 contain conglomerate crystals. 



The histology of the leaf will be treated of under the following sections, (a) epi- 

 dermis, [b] epidermal hairs, (c) stomata, (d) epidermal glands, (e) mesophyll tissue, 

 (f) vascular bündle tissue. The relation of these in the petiole and the basal lamina, 

 in the tendril and in the parts of the pitcher will now be traced. 



(a) The epidermis of the petiole and lamina, in the entire group, consists of a 

 shallow layer of small cells, protected by a thin delicate cuticle. The cells of the 

 upper epidermis of the lamina are typically polygonal and straight-walled, those of the 

 lower epidermis are more or less sinuous in outline. In X. Rafflesiana var. nivea 

 the upper and lower epidermal cells are alike sinuous, and in size as well as shape 



