Recuperative Capacity 27 
leaved trees the stump, if not too old, will have dormant 
buds still alive below the bark to force themselves through 
and make sprouts to replace the lost bole; or else the cam- 
bium layer may form new, so-called adventitious buds for 
the same purpose. 
Lost roots too can be replaced, if conditions are favorable, 
through adventitious buds, a fact of importance in trans- 
planting trees, when usually a part of the root system can- 
not be taken up, and must be replaced by the tree in its 
new position. 
Upon this observation of the replacement of lost parts the 
practice of pruning is based: the tree pruner, by lopping off 
branches and thereby changing conditions of nutrition, 
produces at will new branches, and influences direction, 
character, and amount of development. 
Tree surgery becomes, therefore, next to securing favor- 
able soil conditions, the most important factor in the care 
of trees, for it enables us to remove diseased, malformed, 
undesirable parts without fear of harm to remaining por- 
tions and with the possibility of restoring to symmetry and 
vigor a dilapidated and sickly tree ruin. 
With old age, to be sure, this capacity for replacement 
may be lost in the older parts, and it must also be kept in 
mind that different species are more or less vigorous in 
developing dormant buds. 
The essential points, then, of tree life to be kept in view 
in the care of trees are: — 
1. The living portion of the tree is found in the cam-~ 
bium layer directly under the bark and in the tips of branches 
(buds) and roots. 
2. Root tips and foliage are in direct communication 
with each other and interdependent, relying on each other 
for food. 
