262 A THEORY OF BIRDS' NESTS. 



attempted to elucidate some of these laws in the case 

 of birds, and have shown how the mode of nidification 

 has affected the colouring of the female sex in this 

 group. I have before shown to how great an extent, 

 and in how many ways, the need of protection has 

 determined the colours of insects, and of some groups 

 of reptiles and mammalia, and I would now call parti- 

 cular attention to the fact that the gay tints of flowers, 

 so long supposed to be a convincing proof that colour 

 has been bestowed for other purposes than the good of 

 its possessor, have been shown by Mr. Darwin to follow 

 the same great law of utility. Flowers do not often 

 need protection, but very often require the aid of insects 

 to fertilize them, and maintain their reproductive powers 

 in the greatest vigour. Their gay colours attract in- 

 sects, as do also their sweet odours and honeyed secre- 

 tions ; and that this is the main function of colour in 

 flowers is shown by the striking fact, that those flowers 

 which can be perfectly fertilized by the wind, and do 

 not need the aid of insects, rarely or never have gaily- 

 coloured flowers. 



This wide extension of the general principle of utility 

 to the colours of such varied groups, both in the animal 

 and vegetable kingdoms, compels us to acknowledge 

 that the " reign of law" has been fairly traced into this 

 stronghold of the advocates of special creation. And 

 to those who oppose the explanation I have given of 

 the facts adduced in this essay, I would again respect- 

 fully urge that they must grapple with the whole of the 

 facts, not one or two of them only. It will be admitted 



