360 REMAINS OF STEMS OF DOUBTFUL AFFINITY, ETC. 



pairs and symmetrically with respect to one another ; this form is met with 

 in three or four places in every preparation. The distance between, the 

 bundles is of varying breadth ; sometimes they are in direct lateral contact 

 with one another (Fig. 49). This depends no doubt on the different heights 

 at which the section has passed through them. It is difficult to determine 

 whether this bundle is concentric or collateral, because the bast-portion has 

 been destroyed ; I am also still in doubt respecting the position of the 

 initial strand. It is to be hoped that the fine material which has been 

 recently obtained will soon settle this point. Its tracheal elements are like 

 those of the wood. I am inclined to think that these strands are leaf-traces, 

 though it is strange that they have never been met with in tangential 

 sections in the Dictyoxylon-meshes of the outer rind. Their course must 

 in any case be steeply ascending, since Williamson, on the strength of a 

 longitudinal section which he has figured 1 , declares it to be vertical and 

 parallel to the ring of wood. I cannot however accept the view which 

 he founds on this observation, namely that they are cauline bundles, for 

 reasons which will be mentioned presently. Next we have bundles of 

 occasional but much less frequent occurrence, which are evidently composed 

 of two separate parts. They always stand isolated and unusually close to 

 the outer edge of the wood, where there is always a broad open gap-like 

 primary ray corresponding to them from which they seem to emerge. 

 Each of these bundles consists of an outer normal secondary wood, which 

 has its elements arranged in rows and is usually spread out like a fan, and 

 a primary strand forming its inner boundary and with its tracheides not 

 disposed in any order (Fig. 49 a). This strand is exactly like those which 

 bound the pith, and the impression which it gives is as if one of these 

 strands with the piece of secondary wood corresponding to it had come 

 out through the ring of wood. But as traces of a similar secondary growth 

 are found also in the transverse sections of the bundles of the first kind, 

 where they still lie near together, it is natural to regard all these transverse 

 sections not only as collateral, but as actually belonging to one another. 

 If this is the true view, a point which has yet to be determined, then the 

 emerging strands, which are simple below and have experienced growth in 

 thickness, would lose this growth further on, and ascending in the rind 

 would ultimately separate into two contiguous branches. 



The bundles which have now been described are the only ones which I 

 have myself observed in the material before me. But Williamson 2 has in 

 some cases met with a third kind, which he takes for the attachment-traces 

 of lateral branches, because he was also able to observe their emergence 

 through the meshes of the Dictyoxylon-rind 3 . Their primary strand 



1 Williamson (1), iv, t. 24, f. 11. 3 Williamson (1), IV, t. 22, f. i. 3 Williamson 



(1), iv, t. 25, ff. 14, 16. 



