THE COLOURS OF ANIMALS AND PLANTS 143 



favoured, and have the best chance of securing the 

 most eligible mates. In the case of the Argus 

 pheasant, the wing feathers are enormously elongated 

 and of marvellously beautiful colouring ; while during 

 courtship the male erects his tail like a fan, display- 

 ing his glories to their best advantage. Similar 

 examples are afforded by humming-birds. 



There is no possible doubt as to the appreciation 

 of colour by animals, and the chief differences 

 between men and butterflies would appear to lie in 

 the infinitely better taste displayed by the latter in 

 the selection and combination of colour, both as 

 regards marvellously delicate gradations of tint, and 

 as regards daring combinations of strongly-contrasted 

 colours. It is in fact as rare for a bird or butterfly 

 to offend against good taste in matters of colour, as 

 it is for a man to conform to it. 



The theory of sexual selection,, which was pro- 

 posed by Darwin as supplementary to natural 

 selection, is disputed by Wallace, who holds that 

 brighter colour is the physical equivalent of greater 

 vigour. 



The Colours of Flowers and Fruit. 



The essential parts of a flower are the ovary, in 

 which the ovules are produced, and the anthers, in 

 which the pollen is contained ; and in order that the 

 ovule may give rise to a seed — i.e., to something 

 capable of growing into a new plant — it must be 

 fertilised by the pollen. There is a great advantage 

 as regards the number of. seeds produced, and the 

 vigour of the offspring, if the ovules are fertilised by 



