TO CAUSE FRUITFULNESS. 329 



secretions natural to the variety go on with no more inter- 

 ruption than if the Quince formed no part of the system of 

 the individual. 



If we consider upon what principle the flavour oj particu- 

 lar fruits may be improved, we shall find that it is entirely 

 due to the increased action of the vital functions of leaves. 

 When the sap is first communicated by the stem to the leaves, 

 it has experienced but few chemical changes since it first 

 entered the roots. Such changes as it has undergone have 

 been due rather to the solution of some of the pre-existing 

 peculiar secretions of the individual by the sap in its way 

 upwards through the albernum, than to any other cause. 

 As soon, however, as it enters the leaves, it becomes alter- 

 ed in a variety of ways, by the combined action of air, and 

 light, and evaporation; for which purposes the leaf is ad- 

 mirably adapted by its anatomical structure. Thus altered 

 in the leaves, it ceases to be what we call sap, but becomes 

 the proper juice ; or, in other words, acquires the peculiar 

 character of the final secretions of the individual from which 

 it is formed. Discharged by the leaves into the bark, it is 

 thence conveyed by myriads. of channels of cellular sub- 

 stance throughout the whole system. From these secre- 

 tions, of whatever nature they may be, the fruit has the 

 power of attracting such portions as are necessary for its 

 maturation. Hence it follows, that the more we can increase 

 the peculiar secretions of a plant, the higher will become the 

 quality of its fruit ; and that, on the other hand, the less the 

 plant is in condition to form those secretions, the less will 

 be the quality of the fruit. It is for the purpose of produ- 

 cing the former effect that pruning and training trees are 

 more especially destined. In pruning, we remove all those 

 superfluous branches which overshadowed the remainder, 

 and we endeavour to expose every part to the ireest action 

 of light and air. In training, the same thing takes place, 

 but is increased ; there is not a branch that is not fully 

 exposed to the most d'rect rays of light, and to the freest cir- 

 culation of air, and even to the unimpeded action of the sun 

 in aspects exposed to the south, east or west. This action is 

 obviously most powerful on the south, and hence the higher 

 quality of fruits matured upon that exposure than on any 

 other ; while, on the other hand, fruits raised upon a northern 

 aspect are well known to be less highly flavoured than those 

 from even an open standard. For a similar reason, forced 

 fruits, which are obtained at a period when there is little 

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