INTRODUCTION. JX 



By what means the first tendency to change their 

 nature was given to domesticated plants, we are entirely 

 ignorant. It is probable that it was originally due 

 to accident, and also that it was still mere chance 

 which continued to operate down to very modern times. 

 Philosophers are unacquainted with the reason why 

 there should be any tendency to variation from the 

 characters first stamped on any species by Nature ; but all 

 know that this tendency does exist, and in a most re- 

 markable degree in many species. There is in all beings 

 a disposition to deviate from their original nature when 

 cultivated, or even in a wild state ; but this disposition 

 is so strong in some as to render them particularly 

 well adapted to become subject to domestication : 

 for instance, the dog, the pigeon, and the barn-yard 

 fowl, are cases in which this tendency is most strongly 

 marked in animals ; and domesticated fruits are a parallel 

 case in the vegetable world. 



Without, then, vainly endeavouring to discover the 

 first cause of this disposition to form varieties, let us 

 take it as a naked fact that the disposition exists. Cul- 

 tivators increase this disposition chiefly in two ways ; 

 either by constantly selecting the finest existing varieties 

 for seed, or by intermixing the pollen and stigma of two 

 varieties for the purpose of procuring something of an 

 intermediate nature. The ancients were unacquainted 

 with either of these practices, and consequently their 

 gardens contained few things which would now be 

 deemed worthy of cultivation. The power of obtaining 

 cross-bred varieties at pleasure has only existed since the 

 discovery of sexes in plants ; but as it exerts a most 

 extensive influence over alterations in the vegetable king- 

 dom, it may be considered the most important control- 

 ling power that we possess. 



In sowing seeds for the purpose of procuring improved 

 varieties, care should be had, not only that the seeds be 



