166 THE LESSON OF EVOLUTION 



botanists think that these flowers have retrograded 

 since they were abandoned by insects ; but there 

 seems no reason why they should retrograde, and it 

 is at least possible that some of them remain as 

 they were, and simply mark the stages through 

 which the more advanced flowers have passed. 



By these means the most complicated flowers can 

 be explained ; for every modification which is useful 

 to the plant is due to natural selection, and every 

 modification which is useful to the insect visitors is 

 due to preferential selection. 



In fact, plants suffer from the preferential selection 

 of animals, and they are defended by natural selec- 

 tion. In some cases plants have thus turned de- 

 feat into victory, and by means of the attacking 

 animals have secured the dispersal of their seeds, 

 or the fertilisation of their flowers, or have gone so 

 far as to kill and eat their enemies. Indeed the two 

 processes of preferential and natural selection , when 

 the motive is utility, are generally intimately com- 

 bined. But it is seldom difficult to distinguish one 

 process from the other ; for the first is marked by 

 the exercise of choice and the unselected do not 

 suffer. 



Taking next the motive of pleasure, we see that 

 it includes the greater part of Darw r in's sexual selec- 

 tion. But in some cases it extends beyond the 

 bodily appetites, and we find a real love of beauty 

 developed, especially in birds. Indeed, so far has 

 this preferential selection been carried, as sometimes 

 to come in conflict w T ith natural selection. For the 

 long tail feathers and plumes of matiy birds must 



