162 Detail of Experiments 



occasion, to submit a statement of the results, some of them 

 appearing to me both curious and important. 



At the commencement of my first series of experiments, in 

 the early part of the spring of 1835, the principal object was, 

 to try to ascertain, by different processes of ringing, how far 

 the life of the tree depended upon the cortical layers, or parts 

 external to the wood ; and the alburnous layers, or sap wood, 

 or, to speak more plainly, that portion of the woody structure 

 interior of the cortical layers ; having observed, in studying the 

 works of the most eminent authors on this very important 

 branch of botanical science, that considerable diversity of 

 opinion existed amongst them thereon. For example, it may be 

 recollected that Du Petit Tliouars states, " When the bark, 

 liber, and alburnum were removed, the tree continued to live;" 

 whilst the venerable and celebrated Knight found, by a similar 

 experiment, " that the tree exhibited no signs of vegetation the 

 spring following." 



For these and such like reasons, I was induced, at first, to 

 adopt the experiments alluded to. 



The experiments now about to be described are those which 

 formed a second series, instituted in the early spring of 1836. 



Without at all presuming to discuss the various and con- 

 flicting opinions of authors respecting the channel of the aa^ 

 cending or descending sap, I shall at once proceed to present 

 figures of the subjects of the various experiments, with a simple 

 statement appended to each of their various results ; and, having 

 done this, conclude with some observations respecting them. 



It may be well, also, to state here, that the trees operated 

 upon were the common English elm ( t/'lmus campestris), and 

 about forty-two years of age ; the breadth of the rings cut out 

 being, in each case, about 4 in. 



With these short preliminary remarks, I beg respectfully 

 to throw myself upon the kind indulgence of the high authori- 

 ties before whom I have the honour this day to stand. 



Fig. 20. shows part of the stem of a tree, deprived by 

 ringing of the cuticle and external cortical layers only ; that 

 is, leaving the liher and cambium undisturbed. This, as well 

 as the following experiments (as I have just stated), was done 

 in the month of February, 1836. About the month of May 

 following, a fresh formation of young bark and wood began to 

 take place, as shown at a, from above ; descending, in a very 

 short time, over the whole surface of the ring, except a few 

 spots (b) where the operation had been performed rather 

 deeply. The tree continues to grow as vigorously as any of 

 the same kind in its immediate neighbourhood ; and the excor- 

 ticated part is, this year, nearly filled up with neiso bark, and 

 neX'o layers of sap wood. 



