and on various Plants related to them. Slfl 



place between Monocotyledones and Acotyledones^ and in neglect of the struc- 

 ture of Raffleslacece, and perhaps of some others. Lastly, he baa separated 

 two classes not marked by any sufficient absolute particularity of form or of 



structure; while he has allowed to remain undisturbed the third great sub- 

 kingdom, in which several peculiar natural types exist, and in which, if there 

 be any truth in the MacLeayian zoological system, they are to be found. 



Obs. IV. — The line of argument I hare endeavoured to follow has been 

 drawn with especial reference to three points. 



In the first, I have endeavoured to extend the objections urged by .Mr 

 Robert Brown, founded on the presence of a vascular system, and the absence 

 of any abstract peculiarity in the embryos of these plants. I have also at- 

 tempted to show that these plants are not similar in their parasitism ; and 

 that, even in the moiety I ha ve examined, there would appear to be two re- 

 markably different types of development of the embryo. 



Secondly, I have alluded to the opposition presented, it seems to rae, by 

 such a group as Rhizantheae to the system of nature, a chief part of the plan of 

 which seems to me to consist in an extensive interchange of characters, either 

 positively by structure, or negatively by imitation of structure. 



Thirdly, I have adverted to a want of uniformity in opinion of the founders 

 regarding its rank or value, incompatible, it appears to me, with any group of 

 the system of nature. 



And in conclusion I beg to add, that my impression is that Rhizanthca' form 

 an entirely artificial group, not even sanctioned by practical facility, which is 

 the only merit of an artificial association : and that its adoption is a retro- 

 grade step in the course of philosophical botany, and in direct opposition to 

 those rules on whicb the standard divisions and families of the vegetable 

 kingdom have been hitherto based, and I think in most cases not unsuo 

 fully. " Vera autem scientia ex prcemissis integrw organisationis studio dedita, 

 non lueret in pauciorum signorum deUbutiane, sed omnes omnium organorum 

 modos tenetur perpendere, prcepositd eorum structure et actionis accuratd expo- 

 sitione" Jussieu. 



" Nulla hie valet regula a priori, nee una nee altera pars fructificationis, sed 

 solum simplex symmetria omnium p artiu m" Linnaeus. 



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