"230 Royal Society. 



rays. This zone is generally of unequal thickness on opposite sides 

 of the plant, and contains some barred vessels amongst its re- 

 ticulated ones ; the medullary rays are composed of mural cells. 



The bark consists of thi'ee very distinct layers. The innermost 

 one is very thin, consisting of delicate parenchyma, but which 

 nevertheless has formed a very clearly defined flexible layer; 

 outside this is a thick stratum of coarser but regular parenchyma 

 subdivided in the transverse section into vaguely defined areas by 

 thick \va.\j lines of condensed cells. The peripheral outline of 

 this zone is very irregular, frequently projecting outwards in large 

 angular masses. It is bounded by a proseuchymatous external 

 layer, which is a dwarfed representative of the corresponding one 

 of D. Oldhamium. In the transverse section it exhibits dark radiating 

 bands of fibres, longitudinally disposed, alternating M-ith similar 

 bands of parenchjTua ; but it differs from D. Oldhamium m the 

 narro^Tiess of the latter, and consequently in the more linear form 

 of the cellular areola; of the outer bark. In longitudinal sections 

 of the bark its innermost layer appears as in transverse ones. 

 The middle parenchyma, on the other hand, exhibits remarkal)le 

 differences from its aspect in the transverse section : its cells are 

 arranged in vertical columns ; but these are intersected at intervals 

 of nearly -^ of an inch by horizontal and parallel bands of very 

 dark-coloured cells of a special nature. 



Seven or eight large vasculo-cellular bundles exist in each trans- 

 verse section of the bark. Some of these are located \\'ithin the 

 exogenous layer of the wood, being obviously detached portions of 

 the cells and vessels of the medullary axis ; others occur, in various 

 specimens, at every point between the wood and the outer bark. 

 The author finds that these bundles remained for a time in the 

 immediate neighbourhood of the innennost bark, but that they suc- 

 cessively became detached and moved more rapidly outwards, until 

 each one emerged at the periphery of the bark in one of the 

 prominent angles of the latter, already referred to ; when one bundle 

 has thus reached the periphery, another begins to follow the same 

 centrifugal course. The inference is, that these are foliar bundles, 

 BuppljTJig large leaves or petioles, sparsely grouped round the stem. 

 A single example of a similar centrifugal bundle was found in 

 D. OkUuimium. The seemingly irregular projections of the bark of 

 D. Grievii thus appear to represent angular petioles, and are not the 

 result of merely accidental pressures. A second kind of cylindrical 

 bundle is noticed, consisting of reticulated proseuchymatous cells. 

 It is connected at its central extremity with the medullary 

 parenchyma, ^liilst its peripheral end passes outwards through the 

 bark. It appears to have had the same character as the similar 

 one of U. Oldhamium, having probably been an adventitious root- 

 bundle. 



Somewhat triangular tAvigs or petioles of the above plant are 

 numerous. They consist of a single vascular bundle, located ex- 

 centrically near the cordate base of the triangular transverse section, 

 and surrounded by the three bark-layers seen in the older stems. 



