230 
PRUNING AND THINNING. 
[Part IV. 
Healing over 
an amputated 
branch. 
of the stem will inclose a portion of a mere dead 
bolt without any junction with it; and this is 
one strong reason for not letting trees prune 
themselves , as it is called, that is, for cutting off 
the side-branches before they are killed by their 
neighbours, and for cutting them as close as 
possible to the stem: even then a protuberance 
of the thickness of the bark will be left; and 
where the bark is thick and dead, a part of this 
should be taken away with the branch. 
When a living branch is cut off a vigorous 
tree close to the stem, new growth, both of wood 
and of bark, is gradually and annually deposited 
over the end of it. This new twin growth 
begins as the tree ceases to shoot. About June 
the bark may be observed to separate from the 
wood, and the granulations of this new growth 
may be seen between them; it proceeds in a 
semicircular form on the top and sides of the 
scar, till the growth from one side meets the 
growth from the other side at the lower part of 
the scar; the growth then proceeds towards the 
centre of the circle; and as the new annual 
growth both of wood and bark is deposited on 
the top as well as the sides of this circular wave 
of growth, the level of the top of the wave keeps 
pace with the level of the annually increasing 
