On the Iaconver fib lilt ij of Bark into Alburnum. 139 



an inserted piece of bark can deposit a layer of alburnum, it 

 is at least as difficult to conceive how the same piece of bark 

 can be converted into a layer of alburnum of more than twice 

 its own thickness (and the thickness of the alburnum depo- 

 sited frequently exceeds that of the hark in this proportion), 

 without any perceptible diminution of its own proper sub- 

 stance. The probable operation of the inserted bud, which 

 js a well-organized plant, at the period when it becomes ca- 

 pable of being transposed with success, appears also, in this 

 casej to have been overlooked j for I found that when I de- 

 stroyed trie buds in the succeeding winter, and left the bark 

 which belonged to them uninjured, this bark no longer pos- 

 sessed any power to generate alburnum. It nevertheless 

 continued to live, though perfectlv inactive, till it became 

 covered by the successive alburnous layers of the stock: and 

 it was found many years afterwards enclosed in the wood. 

 It was, however, still bark, though dry and lifeless, and 

 did not appear to have made any progress towards conver- 

 sion into wood. 



In the course of very numerous experiments, which were 

 made to ascertain the manner in which vessels are formed 

 in the reproduced bark*, many circumstances came under 

 my observation which I could adduce in support of my opi- 

 nion, that bark is never transmuted into alburnum; but I 

 do not think it necessary to trouble you with an account of 

 them; for though much deference is certainly due to the 

 opinions of those naturalists who have adopted the opposite 

 theory, and to the doubts of Duhamel, I am not acquainted 

 with a single experiment which warrants the conclusions 

 they have drawn; and I think that were bark really trans- 

 muted into alburnum, its progressive changes could only 

 have escaped the eyes of prejudiced or inattentive observers. 

 In the course of the ensuing spring, I hope to address to you 

 .some observations respecting the manner in which the al- 

 burnum is generated. I am, my dear sir, 



your most obliged obedient servant, 

 Elton, Dec. 29, 1807. " THOMAS AND. KnIGHT. 



* Philosophical Transactions for 1807. 



XXIV. Analysis 



