114 OBSERVATIONS ON THE STATE OF THE 



the preceding experiments : and I then found that in some instances 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 afforded 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 wholly exhausted in the succeeding spring : and hence 

 we are able to account for the several successions of leaves and buds 

 which trees are capable of producing when those previously protruded 

 have been destroyed 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. 



I have also some reason to believe that the matter deposited in the 

 alburnum remains unemployed in some cases during several successive 

 years : it does not appear probable that it can be all employed by trees 

 which, after having been transplanted, produce very few leaves, or by 

 those which produce neither blossoms nor fruit. In making experiments 

 in 1802, to ascertain the manner in which the buds of trees are repro- 

 duced, I cut off in the winter all the branches of a very large old pear- 

 tree, at a small distance from the trunk ; and I pared off, at the same 

 time, the whole of the lifeless external bark. The age of this tree, I have 

 good reasons to believe, somewhat exceeded two centuries : its extremities 

 were generally dead ; and it afforded few leaves, and no fruit ; and I had 

 long expected every successive year to terminate its existence. After 

 being deprived of its external bark, and of all its buds, no marks of vege- 

 tation appeared in the succeeding spring, or early part of the summer : 

 but in the beginning of July numerous buds penetrated through the bark 

 in every part, many leaves of large size everywhere appeared, and in the 

 autumn every part was covered with very vigorous shoots exceeding, in 

 the aggregate, two feet in length. The number of leaves which, in this 

 case, sprang at once from the trunk and branches appeared to me greatly 

 to exceed the whole of those which the tree had borne in the three pre- 

 ceding seasons ; and I cannot believe that the matter which composed 

 these buds and leaves could have been wholly prepared by the feeble 

 v vegetation arid scanty foliage of the preceding year. 



But whether the substance which is found in the alburnum of winter- 

 felled trees, and which disappears in part in the spring and early part of 

 the summer, be generated in one or in several preceding years, there seem 

 to be strong grounds of probability, that this substance enters into the 



