56 PRUNING IN RELATION TO THE PRODUCTION OF TIMBER. 



the first trace of the pith. The most vigorous stems are those 

 that grow most erect, therefore the more a stem deviates from 

 that position the less vigorous it is. Stems increase annually in 

 diameter by the addition of new matter to the outside of the 

 wood and inside of the bark. In the case of the oak, for instance, 

 the duramen or heart-wood is hard, dark, and more durable than 

 the alburnum or sap-wood. The duramen or heart-wood, when 

 young, was simply alburnum or sap-wood, and afterwards became 

 solidified by secretions peculiar to the species. Stems have also 

 the power of propagating their own species by means of leaf buds ; 

 and they also form the channels through which the sap flows from 

 the roots to the leaves. 



Lord Buchan — What are leaves, and what office do they per- 

 form 1 



Forester — The leaves are the lungs of the plants ; they are 

 traversed by veins, and enclosed in a skin or epiderm, which pro- 

 tects them from great variations in temperature. It is in the 

 leaves that all the secretions of plants are formed, and the more 

 they are exposed to light and air, the more active will the vital 

 powers be. This clearly explains why plants languish and die if 

 deprived of their leaves and if crowded to the exclusion of solar 

 light and heat. You will find the same effect from excessive 

 pruning, for if you lop off branches with the leaves close to the 

 trunk, you remove a number of its essential organs. 



Lord Buchan — I shall now revert to our particular subject, and 

 ask you — What effect pruning has upon plant life 1 



Forester — There are various methods of pruning, some of which 

 are injurious to plant life. Close pruning is a system practised by 

 many ; this is doubtless very injurious and detrimental to the 

 value of the timber. Another system of pruning, viz., foreshorten- 

 ing or disbudding, I consider to be beneficial for the future develop- 

 ment of the tree. This system also produces the greatest quantity 

 of sound timber, and consequently the greatest value. 



Lord Buchan — How is close pruning injurious to plant life ] 



Forester — Trees, like most other plants, derive their nourish- 

 ment from the soil, and their nutritive organs are the roots, the 

 stem, and the leaves with the branches — the leaves acting as the 

 lungs of the tree, or its breathing organs. In spring, when the 

 ground is sufficiently warm, the spongioles absorb the nutritive 

 fluid or sap, and pump it into the tree, after which it describes 

 two courses, viz., an ascending and a descending one. The ascend- 



