INTRODUCTION. LEAVES. , s 



nature as applied to the vegetable kingdom. As previously indicated, they absorb 

 gases from the atmosphere, and benefit by those of them that would otherwise vitiate the 

 air. They purify, elaborate, and assimilate the crude sap that is supplied by the roots, 

 and secrete what is necessary for the health of the trees and the formation, production 

 and sustenance of fruit. They draw moisture from the earth and distribute it through 

 their pores, and when the supply is inadequate for the demands of evaporation, under 

 the influence of the sun, they wither and die. But they cannot perfectly fulfil their 

 function if they themselves are not perfect in structure, substance, and colour, and none 

 of these essential conditions can be provided in the absence of appropriate food, light, 

 air, and cleanliness. Soil deficient in fertility cannot supply the requisites for healthy 

 growth, and the leaves are then small and weak, because ill- fed ; if it is deficient in 

 mineral, while containing an excess of nitrogenous matter, they may be large but will 

 be lacking in tissue, and hence soft and flaccid ; if infested with insects the foliage 

 will have the sap extracted, and in other respects be unable to perform the functions 

 that are absolutely necessary for the health of the tree. No kind of soil or of 

 manure, and no system of pruning can compensate for defective leaves. The object 

 of the cultivator, therefore, must be to have them as nearly perfect as possible. 

 Recognising this, he will perceive the necessity of having the ground in the best 

 mechanical condition, free from stagnant moisture, and sufficiently charged with 

 fertility for imbibition by the roots ; also of full exposure of the leaves to the direct 

 action of light for sound structural development. In view of this he will be conscious 

 of the great evil of overcrowding the growths and consequently take care to prevent it. 

 lie will not prune recklessly or thoughtlessly for multiplying shoots needlessly, nor 

 apply manures and fertilisers extravagantly for promoting grossncss of habit. He will, 

 or should, comprehend the fact that good leaves arc builders of tissue, strengtheners of 

 trees, and manufacturers of fruit, and, conversely, that leaves of an opposite character 

 are weakeners by abstracting instead of preparing and secreting nutrient matter in 

 the trees. 



Possessing sound knowledge of these essential organs the grower of fruit will not be 

 misled by the mere size or superficial area of leaves, but will regard firmness in texture, 

 substance and colour as matters of far greater importance ; stout, good, food-storing, and 

 health-sustaining leaves (a, , Fig. 2, p. 16) cannot be had in the absence of full light; 

 and the denser the shade the greater is the expansion of leaves, the thinner they are in 

 texture and the paler in hue. In proportion to the deficiency of light the surfaces of 



