is dcposUed during I fainter,' 313 



I found that the wmter-felled wood had coinmiinlcatcd a 

 much deeper colour to the water in which it had been in- 

 fused, and had raised its specific gravity to 1.002. The 

 specific gravuy ot the water in which the summer-felled 

 wood had :n the same manner been infused was 1.001. The 

 wood in all the preceding cases was taken from the upper 

 parts of the poles, about eight feet from the ground. 



Having observed, in the preceding exprinients, that the 

 sap of the sycamore became specifically lighter when it had 

 continued to How during several days from the same incision, 

 I concluded that the alburnum in the vicinity of such in- 

 cision had been deprived of a larger portion of its concrete 

 or inspissated sap than in other pai ts of the same tree : and 

 I therefore suspected that I should find sinnlar etiects to 

 have been produced by the young annual slioots and leaves; 

 and that any given weight of the alburnum in their vicinity 

 would be found to contain less extractive matter than an 

 equal portiiai taken from the lower parts of the same pole, 

 where no annual shoots or leaves had been produced. 



No information could in this case be derived from the 

 difference in the specific gravity of the wood ; because the 

 substance of every tree is most dense and solid in the lower 

 parts of its trunk : and I could on this account judge only 

 from the quantity of extractive matter which equal portions 

 of the two kinds of wood would afford. Having therefore 

 reduced to pieces several equal portions of wood taken from 

 different parts of the same poles, which had been felled in 

 May, I poured on each portion an equal quantity of boiling 

 ■water, which I suffered to remain twenty hours, as in the 

 preceding experiments : and 1 then found that in some in- 

 stances the wood from the lower, and in others that from 

 the upper parts of the poles, had given to the water the 

 deepest colour and greatest degree of specific gravity ; but 

 that all had aff'orded much extractive matter, though in 

 every instance the quantity yielded was much less than I 

 had, in all cases, found in similar infusions of winter- 

 felled wood. 



It appears, therefore, that the reservoir of matter deposited 

 in the alburnum is not whollv exhausted in the succeeding 

 sprmg : and hence we arc able to account for tlie seve- 

 ral successions of leaves and buds which trees are capable of 

 producing when those previously protruded have been de- 

 stroyed by insects, or other causes ; and for the extremely 

 luxuriant shoots, which often spring from the trunks of 

 trees, whose branches have been long in a state of decay. 



T. have also some reasons to believe that the matter depo- 

 sited in the alburnum remains unemployed in some cases 

 6 during 



