and on the Structure o/'IIvdnora alricana. l'X\ 



same natural class, in giving an account of a new and remarkable irenu> <>l 

 the latter family*. 



At present I shall only remark, that the sole remaining character employed 

 to unite these two families and supposed u> distinguish them from all others. 

 namely the simple or acotyledonous embryo, exists equally in Orchidete. 

 And if it be employed along with those character! connected with their 

 peculiar ceconomy, namely the imperfect development of leaves, tin- want of 

 stomata and absence of green colour, the class cannot he limited to RaffUsi- 

 acece ami Balanopliorea\ for an embryo of exactly the smic kind exktl 

 Orobanche, and other, perhaps all other, genera parasitic on roots, a remark 

 which I made, though not with sufficient precision, in my former essay. Hut 

 such a classification, though founded on seemingly very important technical 

 characters, would hardly he received in a strictly natural arrangement, and 

 it seems to me quite as paradoxical to approximate two such genera as Rafflena 

 and Balanopkora. 



RAFFLESIA ARNOLDI. 



Rafflesia Arnoldi, R. B. in Linn. Sue. Transact, vol. xiii. p. 201. tabs. 15-22. 



Mas. 

 Rafflesia Titan, Jack in Malayan Miscell.. Append, to vol. i. 



approximated, their possible origin from one common basis or thallus is more readily suggested, espe- 

 cially on considering that in the former genus, which is dioecious, each group of parasites is generally, 

 perhaps always, exclusively of one sex ; and that these groups, often of great density, not unfrequently 

 surround completely the branch of the stock. But although this view did occur to me as not very im- 

 probable, and as tending to remove some of the apparent difficulties, I have never been able to trace 

 any substance decidedly distinct from the proper tissue of the stock : there are, however, some appear- 

 ances favouring the hypothesis in both genera, especially in Pilostyles, but which require careful 

 examination in the living plants. 



* This genus, which was first found by Francis Masson, is the Mysfropetafon of Mr. Harvey (in 

 South Afr. Gen. p. 418), who has described two species, from both of which Masson's plant is per- 

 haps distinct. 



I may here advert to a note at p. 225 of my former memoir (in Linn. Soc. Trans, vol. xiii.), in which 

 1 thought it not improbable that a parasite briefly noticed by Isert (in Reise nach Guinea, p. 283) 

 might be related to Rafflesia. I have now, however, reason to believe that Isert's plant is the Thou- 

 ningia sanguinea of Vahl (in Act. Soc. Hist. Nat. Hafn. t. vi. p. 124, t. 6, and Schumacher, Guineische 

 Plant, p. 431), a genus nearly related to, if really distinct from Balanophora. 



