THE STEM OF VASCULAR PLANTS. 195 



idea, that the fibres of the branch penetrate the trunk ; 

 perhaps I should have done better in saying that certain 

 fibres of the trunk passed through the vertical bundles, 

 and penetrated the branch. 



This suspicion seems authorized by the examination 

 of the trunk of Xanthorhoea hastilis. I possess a piece 

 of this singular plant, discovered in New Holland by 

 M. Gaudichaud. At the first view of a vertical section 

 of it, one would completely take it for a Dicotyledon, 

 and in fact I at first feared that there had been some 

 mistake about it ; but, on the one hand, Gaudichaud, 

 whose accuracy is well known, distinctly remembered 

 the origin of this specimen ; and, on the other hand, on 

 examining it, an organization is perceived, which, if it be 

 not similar to the usual state of Monocotyledons, differs 

 still more from that of Dicotyledons. This piece presents 

 a very thick and wrinkled cellular zone, perfectly re- 

 sembhng that of an Exogen ; the woody body is formed, 

 1st, of vertical fibres, rather loose, and very like those of 

 Palms, or of Yucca ; 2d, of other fibres, which, radiating 

 from the centre, pass through all the preceding, cutting 

 them at nearly right angles, and are prolonged even 

 through the cellular zone, under the form of fine lines : 

 these horizontal fibres resemble medullary rays in their 

 position, but differ from them in their nature ; they are not 

 vertical plates, but fibres, joined two or three together. 

 Do these fibres, wliich spring from the central part — are 

 directed towards the foliaceous organs — and thus remain, 

 as it were, inserted into the trunk — serve for the origin 

 of the leaves ? This suspicion would seem to be au- 

 thorized by considering that the leaves of Xanthorhoea 

 are very numerous, and disposed not only upon the 

 summit but throughout the length of the branches. All 

 the cortical part, and the trunk of this tree, are impreg- 

 nated with a reddish brown matter, which appears to be 



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