I PROLEGOMENA. 15 



trees against the most favourable of south walls, a 

 waste of time and trouble. 



But it is extremely important to note that, the 

 state of nature remaining the same, if the pro- 

 duce does not satisfy the gardener, it may 

 be made to approach his ideal more closely. 

 Although the struggle for existence may be at 

 end, the possibility of progress remains. In dis- 

 cussions on these topics, it is often strangely 

 forgotten that the essential conditions of the 

 modification, or evolution, of living things are 

 variation and hereditary transmission. Selection 

 is the means by which certain variations are 

 favoured and ther progeny preserved. But the 

 struggle for existence is only one of the means 

 by which selection may be effected. The endless 

 varieties of cultivated flowers, fruits, roots, tubers, 

 and bulbs are not products of selection by means 

 of the struggle for existence, but of direct selec- 

 tion, in view of an ideal of utility or beauty. 

 Amidst a multitude of plants, occupying the same 

 station and subjected to the same conditions, in 

 the garden, varieties arise. The varieties tending 

 in a given direction are preserved, and the rest 

 are destroyed. And the same process takes place 

 among the varieties until, for example, the wild 

 kale becomes a cabbage, or the wild Viola tricolor 

 a prize pansy. 



