FUNCTION.] GAUDICHAUD'S VIEWS. 197 



It has, however, had the advantage of being supported by 

 M. Gaudichaud ; an account of whose hypothesis is given in 

 the sixth edition of Achille Richard's Nouveaux Elemens de 

 Botanique, p. 167. The principal peculiarity in M. Gaudi- 

 chaud's views consists in his assigning the growth of plants 

 to a sort of polarity produced by the action of two opposite 

 systems, of which the one, or ascending, consists of trachen- 

 chym exclusively, the other, or descending, of bothrenchym 

 and pleurenchym. The line of demarcation between them 

 is called the mesocauleorhiza. The leaf would appear to be 

 regarded as a form of stem divided into three parts, of which 

 the lowest is the internode from which the leaf emanates, the 

 middle the petiole, the upper the lamina. The line of 

 demarcation between the internode and petiole is called 

 the mesophytum ; that between the lamina and petiole the 

 mesophyllum. 



Setting aside mere hypothesis it seems incontestable that 

 wood, in whatever manner it is deposited, is created out of 

 organisable matter prepared in the leaves, or their equivalents, 

 and therefore derived from them. This being so it matters 

 nothing whether the matter descending from leaves, and 

 acquiring the condition of wood, be theoretically called roots, 

 or by some other name : it is certainly descending matter. 



The most important of the objections which have been 

 taken to this opinion are the following : If wood were really 

 organised matter emanating from the leaves, it must neces- 

 sarily happen that in grafted plants the stock would in time 

 acquire the nature of the scion, because its wood would be 

 formed entirely by the addition of new matter, said to be 

 furnished by the leaves of the scion. So far is this, however, 

 from being the fact, that it is well known that, in the oldest 

 grafted trees, there is no action whatever exercised by the 

 scion upon the stock ; but that, on the contrary, a "distinct 

 line of organic demarcation separates the wood of one from 

 the other, and the shoots emitted from the stock, by wood 

 said to have been generated by the leaves of the scion, are 

 in all respects of the nature of the stock. Again, if a ring of 

 bark from a red-wooded tree is made to grow in the room of 

 a similar ring of bark of a white- wooded tree, as it easily 



