^^^ ON THE STRUCTURE AND 



Cephalotus to those of Nepenthes, leads to a comparison in 

 the first place of these two genera. But although both are 

 apetalous, and in the parts of the flower deviate from the 

 quinary or prevailing number in Dicotyledones, yet they 

 317] differ in so many other important characters that they 

 cannot be considered as nearly related . 



The place of Nepenthes in the natural series I have long 

 since^, in my account of RafHesia, suggested to be near 

 Aristolochise or Asarinae, without, however, intending to 

 include it in that family. 



This approximation was adopted by M. Ad. Brongniart, 

 who, however, went further, having absolutely referred 

 Nepenthes to Cytinese. 



The union of plants so utterly unlike in appearance and 

 (Economy, and so different, it may be added, in many 

 of their most important characters, seems to have been 

 generally regarded as somewhat paradoxical ; and accord- 

 ingly Professor Link, in 1829, has established Nepenthes 

 as a section or tribe of Aristolochiee, and Dr. Bartling and 

 Mr. Lindley, in 1830, have considered it as forming a 

 distinct natural family. 



To the numerous and obvious distinctions between Cy- 

 tinese and Nepenthes may be added the no less important 

 differences in their internal structure. For while Cytineae, 

 like most, perhaps all, other plants parasitical on roots, are 

 destitute of spiral vessels. Nepenthes exhibits these vessels 

 in the greatest degree of development and abundance, and 

 also produces them in parts in which they are hardly to be 

 met with in any other dicotyledonous plant. 



Thus, in addition to the dense circle or stratum of spiral 

 vessels existing in the stem between the outer parenchyma 

 and the wood, they are found also singly or scattered in the 

 pith, in the loose parenchyma situated between the wood and 

 the bark, if it may be so called, even in the fibres of the 

 root, and everywhere in the substance of the leaves, the 

 pitchers, calyx and capsules. And between these solitary or 

 scattered spiral vessels, which are often of considerable 



' Transact. Linn. Soc. vol. xiii, p. 219 [vol. i,p. 386]. 



