1 io 
Mr. Knight on the Inconvertibility of Bark , &c. 
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 opinion, 
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 transmuted into alburnum, 
its progressive changes could only have escaped the eyes of 
prejudiced, or inattentive observers. In the course of the en- 
suing spring, I hope to address to you some observations 
respecting the manner in which the alburnum is generated. 
I am, my dear Sir, 
your most obliged obedient servant, 
Elton, Dec. 29 , 1807. THOMAS AND. KNIGHT. 
* Phil. Trans, for 1807. 
