Part IV.] 
PRUNING AND THINNING. 
259 
ing, contributes to the growth and nourishment 
of the roots. In such cases, trees are often 
killed by being left “to see where they break 
out.” They should be cut immediately: “ Bis 
dat qui citb dat.” This waste of the sap in the 
stem and branches, without the power to return 
to the root, is the reason why trees which are 
barked round just above the earth in general die. 
If young trees are cut down just above the 
earth, they shoot out again freely and continue to 
grow ; but if they are only barked, the sap going 
up the heart-wood diminishes the chance of an 
outbreak below, and without this outbreak the 
roots must die from a want of descending sap. 
If a branch is not cut at the foot of a living 
twig, its end should be again cut off at the foot 
of the new shoot, in order that the descending 
sap of the new shoot may deposit wood and 
bark over the cut end. If long stump-ends are 
allowed to remain, they rot before the new 
growth in diameter of their stock has inclosed 
and covered them. 
Near natural ponds, where the whole soil 
holds, the presence of trees is beneficial, from 
their prevention of evaporation, and from the 
condensation which takes place in moist warm 
weather, particularly on smooth-barked trees; 
s 2 
