234 
PRUNING AND THINNING. 
[Part IV. 
Explanation of 
Plates I. and II. 
lip of the bark, which also dies. It comes 
from springs far above these and independent of 
them. The new deposit of wood and bark over 
the wounds of trees is the brimrning-over of the 
descending stream of growth between the wood 
and the bark, and has nothing to do with the 
dead wood of the wound, or the dead rim of 
bark which surrounds it. It would continue to 
grow over the dead wood if it were stuck full 
of nails or tenter-hooks. It does continue to 
grow over it even when it is rotten ; and when 
the wood has quite mouldered away, the growth 
still continues, but, as there is no basis on which 
to deposit, it curls round on itself. 
Since the publication of the first edition of 
this treatise, I have found an example which 
will throw light on what has been stated. 
Plate I. is an engraving of a piece of a board 
planed down to a level with the centre of the 
pith of the stem, and of the pith of a branch. 
The board is from a Scotch fir cut in Brookwood 
Park, Hampshire. 
A is intended to represent the upper end of 
the board, which has been cut across ; B, the 
lower end. Both of these cross-cut ends are 
turned so as to face the same way with the side 
of the board, which is cut lengthways, so that 
