SECT. VI. THE CAUDEX. 285 



have exemplified rather incorrectly to the different 

 tribes of plants. 



This remark alludes to the two different modes of As exem- 

 internal structure, which they have indeed demon- monocoty- 

 strated and described in the most masterly manner 

 in the above mentioned papers, and presumed, as it 

 would appear, if not altogether to exhaust the sub- 

 ject, at least to correspond respectively to the two 

 different divisions of plants known by the appella- 

 tion of Monocotyledonous plants on the one hand, 

 and Dicotyledonous plants on the other ; the caudex 

 of the latter being represented as composed of dis- 

 tinct, concentric, and divergent layers, decreasing 

 in solidity from the centre to the circumference, 

 and containing the pith in a canal ; and the caudex 

 of the former being represented as exhibiting no 

 evident traces of concentric or divergent layers ; but 

 bundles, or assemblages, of large and woody fibres, 

 decreasing in solidity from the circumference to the 

 centre, and interspersed throughout a pith.* 



But the fact is, that the two modes of internal Which do 

 structure here specified do not uniformly and re- haust^he 

 spectively pervade the two grand divisions of plants sub J ect> 

 now in question to the exclusion of each other ; 

 there being many dicotyledonous plants whose mode 

 of internal structure is precisely the same with 

 that which is here described as peculiar to monoco- 

 tyledonous plants, as may be exemplified in most 

 herbs; although the converse of the proposition 

 * Defon. Mem. de 1'Instit. Nat. tome i, 



6 



