294 Scientific Proceedings, Royal Dublin Society. 



green colour, like the young leaves of the ordinary form. A single plant of 

 D. nmnmularia often covers an area of several square feet, completely covering 

 tliat part of the trunk or branch on which it grows. 



D. rafflesiana is heterophyllous, having three well-marked forms of leaf 

 (though one of these is confined to the young plant), and is also heterorhizal. 

 The early stages of germination are identical with those of D. mtmmularta; 

 and the iirst foliage leaves are very similar to and often indistinguishable 

 from those of that plant. Usually three to five pairs of these leaves are 

 produced; they may also be borne by the first lateral branches; sooner or 

 later, however, the pitcher-leaves appear, either on a continuation of the main 

 axis, or on a lateral branch. Intermediate forms of leaf are not imcommonly, 

 though not always, found between the first foliage and the pitcher-leaves. 

 These intermediate forms have their upper surface very convex, and the lower 

 correspondingly concave, the tip being sliglitly inturned ; more rarely there 

 is a series of leaves in which the convexity increases and the mouth narrows 

 until the tj'pieal pitcher form is reached. 



The pitcher-leaf is formed by the more rapid growth of the central part 

 of the lamina, so that a bag-form is produced, the outside corresponding to 

 the upper surface of the leaf and the inside to the lower. The mature 

 pitcher reaches a length of about 12 cm. ; it is of a light yellowish green 

 colour externally, and of a deep purple colour within. The small entrance, 

 or mouth of the pitclier, is bounded on one side by the short, stout petiole, 

 on the other by the inturned edge of the leaf. The spout-like, inturned tip 

 of the leaf forms a short passage from the mouth into the pitcher. This 

 passage will barely admit the entrance of a small goose-quill. The mouth of 

 the pitcher is normally turned towards and pressed against the supporting 

 branch. 



As in D. nummularia, a pair of adventitious roots spring from the ventral 

 surface of each node, close to tlie insertion of the petioles ; in addition to 

 these, the pitcher-bearing branches have other roots — ^pitcher-roots — which 

 arise in pairs from the dorsal surface of the nodes. Each root makes its 

 appearance from the stem very close to the petiole, and then grows along the 

 petiole into the interior of the pitcher, where it branches freely. Rarely, in 

 the plants examined by me, does the pitelier-root appear to arise from the 

 petiole ; in such cases, by pulling gently on the root, it tears through the 

 superficial tissues of the petiole ; and its real origin from the stem is readily 

 seen. Scott and Sargaut agree with Treub in describing the origin of the 

 pitcher-root from the petiole as the normal one.' No doubt plants from 



'Scott and Sargant on the Pitchers of Disdiidia rnflesiona (yfAll.), " Annals of Botany," 

 vol. vii, No. xxvi, 1893. 



