Linnccan Society. 7i 



Transactions ; and, in connexion with the question of its place in a 

 natural arrangement, he introduces a more detailed description and 

 figures of Hydnora africana, than have hitherto been given. The 

 drawings of Rafflesia which accompany the paper are by Francis Bauer, 

 Esq., and those of Hydnora by the late Mr. Ferdinand Bauer. 



From a comparison of Rafflesia with Hydnora and Cytinus, he is 

 confirmed in the opinion expressed in his former paper, but founded 

 on less satisfactory evidence, that these three genera, (to which 

 Brugmansia of Blume is now to be added,) notwithstanding several 

 remarkable peculiarities in each, may all be referred to the same na- 

 tural family j and this family, named by him Rafflesiaceae, he continues 

 to regard as being most nearly allied to Asarinae. 



He does not, however, admit an arrangement lately proposed by 

 M. Endlicher, and adopted by Mr. Lindley, by whom these genera 

 are included in the same natural class with Balanoplwrea of Richard j 

 an approximation founded on their agreement in the structure of Em- 

 bryo, and on the assumed absence of spiral vessels. On this subject 

 he remarks, that in having a homogeneous or acotyledonous Embryo, 

 they essentially accord, not only with many other plants, parasitical on 

 roots, which it has never been proposed to unite with them, as Oro- 

 banche, &c, but also with Orchidese, their association with which 

 would be stiil more paradoxical. And with respect to the supposed 

 peculiarity in their vascular structure, he states that he has found 

 spiral vessels not only in Rafflesia, (in which he had formerly denied 

 their existence,) and in Hydnora and Cytinus, but likewise in all the 

 Balanophorese examined by him, particularly Cynomorium and He- 

 losis, as Dr. von Martius had long since done in Langsdorfia, and 

 Professor Meyer very recently in Hydnora. 



In his observations on the ovulum of Rafflesia, he gives a view of 

 its early stages of development, and which he extends to Phsenoga- 

 mous plants generally, in some respects different from that taken by 

 M. Mirbel, who considers the nucleus of the ovulum, in its earliest 

 state, as inclosed in its coats, which gradually open until they have 

 attained their maximum of expansion, when they again contract 

 around the nucleus, and, at the same time, by elongating, completely 

 inclose it. Mr. Brown, on the other hand, regards the earliest stage of 

 the nucleus as merely a contraction taking place in the apex of a preex- 

 isting papilla, whose surface, as well as substance, is originally uniform, 

 and that its coats are of subsequent formation, each coat consisting, at 

 first, merely of an annular thickening at the base of the nucleus, 

 which, by gradual elongation, it entirely covers before impregnation 

 takes place. 



But this mode of development of the ovulum, he remarks, though 

 very general, is not without exception ; for in many, perhaps in all, 

 Asclepiadeae and Apocinese, the ovulum continues a uniform cellular 

 tissue, exhibiting no distinction of parts until after the application of 

 the pollen tube to a definite part of its surface, when an internal se- 

 paration or included nucleus first becomes visible. 



