334 JOURNAL OF THE EOYAL HOETICULTUEAL SOCIETY. 



result will be that the supply of food material that is made — not being 

 used up in the production of growth, will all be used in making fruit buds. 



Thus we see how it is that root-pruning will throw a tree into fruit by 

 allowing the elaborated (organic) sap to predominate over the crude 

 (inorganic). This puts the whole question of fruitfulness into a nutshell. 

 Predominance of root sap means growth ; predominance of leaf sap, fruit. 



This is illustrated in another way. It is often said that canker causes 

 a tree to fruit. It is not, of course, the disease that causes this, but 

 merely that the elaborated sap on its way to stems and roots is stopped by 

 the damaged bark and held up in the branch. The buds therefore get an 

 abnormal supply of food material which aids their development into fruit 

 buds. The ancient practice of bark-ringing is based on the same principle, 

 as is also that of wassailing the apple trees. Headers of Phillpotts' 

 "Children of the Mist " will remember the " wassailing" of the Devon- 

 shire orchard described therein. The ceremony of discharging guns at 

 the trees had no doubt the practical result of causing many wounds in 

 which canker would establish itself and thus check the downward sap 

 flow, and thus the fruitfulness which was believed to follow this ceremony 

 would be capable of a simple explanation. Another well-known practice, 

 that of bending down a branch to make it more fruitful, also owes its 

 success to the fact that it would be more difficult for the elaborated sap 

 to flow out of the branch into the stem and thence to the roots. 



All fruit-growers will know how easily the middle portion of a fan- 

 trained tree will grow compared with the side branches which are parallel 

 to the ground. This is due to the fact that the straighter the passage the 

 quicker the flow of water. The centre branches take more than their- 

 share of root sap, and the freedom with which the elaborated product 

 flows back to the root prevents those strong branches attaining the 

 fruitfulness of those situated at the sides. 



Other examples might be given, but enough has been said to illustrate 

 the point and to show how a knowledge of physiology may be of value to 

 the pruner. It is manifestly impossible in the short space of a lecture 

 to do more than roughly sketch these possibilities. 



In the different conditions in which the pruner finds his subjects, in 

 their varying constitutions and habits, it is evident that mere dogmatic 

 rules for pruning cannot suffice. A knowledge of the principles of plant 

 growth will place him on a sure foundation from whence he can estimate 

 the value of rules and their exceptions, and will lead him to approach 

 his work in the spirit which is expressed in the motto of our sister 

 Society, " Practice with Science ! " 



