204 



PRUMNG AND TlilNNIXG. 



PT. IV. 



But if a dead branch is left till it becomes rotten where 

 it joins tlie stem, as there is no firm surface for the de- 

 posit of new wood, the new growth curls round upon 

 itself, and a hole remains in the stem of the tree. In 

 this the water, running down the stem, lodges and 

 saturates the parts. This, with the action of the 

 oxygen of the air, continues the process of decay, 

 which is communicated by contact to the heart-wood 

 of the tree: and hollowness of the centre is almost 

 always thus caused by rotten branches from above, not 

 by rotten roots from below. This is the fruitful source 

 of destruction to our timber-trees, to the life of which, 

 otherwise, there is apparently no necessary limit. Very 

 httle care may avoid this chief cause of decay. 



It is not meant to assert that there is no limit to the 

 age, or height, or bulk which in a case of optimism 

 trees may attain to ; but at present we know of none. 

 The whole appears to depend on circumstances ; that 

 is, even if we knew the maximum age, or height, or 

 bulk which any particular sort of tree had ever attained 

 to, it would not follow that under more favourable cir- 

 cumstances others might not have surpassed it. 

 Prejudice Tlic prejudicc against pruning with a saw, or the 



pruning 



idea of the necessity of afterwards cutting the wounds 



with a saw, 



a vulgar q^q^ with a sharp instrument, is a vulo^ar error. The 



error. ^ ° 



new formation of wood and bark over an amputated 

 branch is not from the cut wood, which dies, or from 

 the lip of the bark, which also dies. It comes from 

 springs far above these and independent of them. The 



