Part IV.] 
PRUNING AND THINNING. 
231 
girthing of the tree, and when the ring closes in 
the centre no indentation is left; and each suc¬ 
ceeding year the new annual ring of wood and 
of bark is deposited over where the branch was, 
with as much regularity as on any other part of 
the stem, nor is any distortion of the grain of the 
wood or diversion of the current of the sap occa¬ 
sioned after the healing is completed. The end 
of the branch will die and dry in, possibly to 
the extent of the cross-grain occasioned by it, 
and a very slight and inconsiderable flaw will 
remain in the timber where the living wood is 
deposited on this dead surface; this flaw will 
be no greater than that occasioned by a small 
piece of bark being accidentally knocked off a 
tree. 
The rapidity of the healing will be directly 
as the rapidity of the growth in girthing of the 
stem. Suppose the width of the new annual 
layer of wood to be a quarter of an inch, it 
would take twelve years to heal over the end of 
an amputated branch, whose diameter was six 
inches. During those twelve years, the grain of 
the new wood deposited over the end of the 
branch will be curled; after that, straight¬ 
grained wood will be annually deposited. These 
are reasons for preventing the undue growth of 
Q 4 
