INTRODUCTION. 23 



apples and pears that have sound kernels swell the most freely. This is evident on 

 examining fruits that swell on one side only, shrinking and cracking on the other, for 

 on dissection the seeds or pips are often, if not always, defective on the failing side and 

 sound on the other. In those kinds, therefore, which are prone to fall prematurely or 

 not swell satisfactorily the importance of fertilisation is apparent. Soil lighfly charged 

 with minerals, such as lime and potash, and at the same time of a dry nature, favours 

 the seed at the expense of the fleshy envelope or fruit ; while if nitrogenous manure 

 preponderates and moisture abounds, the flesh is thickened and the fruit enlarged, 

 though an excess of such stimulants as nitrate of soda is inimical as inciting the pro- 



Fig. 5. FRUIT: (a) Drupe or stone-fruit. (A) Pome or pippin fruit. 



duction of soft stems and leaves. It follows, then, that fruit should not be injudiciously 

 forced by liquid manure, and it ought not, as a rule, to be applied until after the seeds 

 are formed, and should be discontinued when the ripening process commences. 



"When fruits are young and green they possess the same chemical constituents 

 as leaves, hence are said, and truly, to "taste of the tree." As they increase in 

 size they become sour by the presence of acids, such as tartaric acid in the grape, 

 malic acid in the apple and gooseberry, citric acid in the orange and lemon. With a 

 further advance the acids become neutralised by alkalies, and are eventually, as in the 

 ripening process, converted into grape sugar. Yet, though a number of different 

 varieties are grown on the same tree, either of apples or other fruits, and hence 



