78 THE EVOLUTION OF THE FLOWERS 



The active flying insects naturally developed very 

 richly when the earth became covered with iSowers. 

 One has only to watch the swarms of them hovering 

 about the flowers in the summer to realize how the 

 two worlds would grow simultaneously. Probably 

 everybody now knows that the insect is useful to the 

 flower in return for the food it gets. It is an advan- 

 tage when the pollen of one plant is taken to fertilize 

 the seed of another plant, instead of fertilizing its 

 own seed. The wind may perform this service, and 

 does in the case of some plants; but it is a clumsy 

 and wasteful process. It is far more effective when 

 the little bee, poking into the depths of the flower for 

 the honey which is prepared for it there, gets the 

 pollen on its body, by rubbing against the stamens, 

 and unconsciously carries it to the next flower. 

 This is "cross-fertilization," which is better than 

 self-fertilization. 



It is generally believed that the colours of the 

 flowers are a sort of advertisement to the insects. 

 The yellow leaves of the buttercup — they are, like 

 all other parts of the flower, transformed leaves — 

 practically mean to the distant insect, "Free food 

 here." There has been some dispute in recent science 

 as to whether the insects really are attracted by 

 colours, but the experiments that have been made 

 seem to show that this is the case. Naturally, the 

 insects and the flowers must have developed together. 

 It takes ages to evolve any arrangement of this kind, 



