SELECTION 163 



Carrion Crow, and the Australian Magpie can find 

 their mates without any marks recognisable by us, 

 it is not easy to see why recognition-marks should 

 exist at all. Still I believe that these marks exist, 

 because we see them in the higher animals only. 

 The lower animals and plants, in which intelligence 

 is absent or of a very low order, have not the same 

 variety of colour-patterns as we see in the higher 

 animals. 



Change in habit is largely due to preference for a 

 certain food. After the choice is made, natural 

 selection comes into play. For instance : a cer- 

 tain flower secretes more nectar than usual, and a 

 bee prefers it to other flowers, and frequently 

 returns, guided by colour, shape, or scent. Natural 

 selection now begins ; for as the visits of the bee are 

 beneficial to both animal and plant, both get more 

 and more adapted to each other. But it is evident 

 that the first steps of a beneficial variation may be 

 fostered and accumulated by preferential selection 

 until the variation is of sufficient importance to be 

 exploited by natural selection. 



The structural growths which in many flowers 

 necessitate the visits of special kinds of insects or 

 birds' to fertilise them, are also probably due to pre- 

 ferential selection, for it is very doubtful whether 

 they are useful to the plants. No doubt the secre- 

 tion of honey, the bright corolla, as well as all the 

 devices by which plants prevent the visits of non- 

 flying insects, or by which they entrap small flies, 

 are due to the action of natural selection, for all of 

 them are useful to the plant. But it cannot be of 



