INTRODUCTION. XV11 



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 substance throughout 

 the whole system. From these secretions, of whatever 

 nature they may be, the fruit has the power of attract- 

 ing such portions as are necessary for its maturation. 

 Hence it follows, that the more we can increase the pe- 

 culiar 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 producing 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 freest action of light and 

 air. In training, the same thing takes place, but is 

 increased ; there is not a branch that is not fully ex- 

 posed to the most direct rays of light, and to the freest 

 circulation 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 light, 

 cannot be compared with those which are matured in 

 the full blaze of a summer sun ; and hence melons 

 grown in frames covered with mats, and carefully ex- 

 cluded from the influence of that solar light which is 

 indispensable to them, have, whatever may be their ex- 



