95 
the true Sap of Trees is deposited during Winter. 
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 suc- 
cessions 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 reasons 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 trans- 
planted, 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 ex- 
pected every successive year to terminate its existence. After 
being deprived of its external bark, and of all its buds, no 
marks of vegetation appeared in the succeeding spring, or 
early part of the summer: but in the beginning of July 
