BIRDS' NESTS AND EGGS 363 



In these charming objects the chief peculiarity which 

 claims our notice is their beautiful ground colours and varied 

 markings. Why, we naturally ask, do these eggs exhibit 

 such diversity of colour ? Why are some eggs white, whilst 

 others are painted in tints rich and beautiful ? or why are 

 some spotless and others thickly marked? Some persons 

 may urge that these colours are developed for no object 

 beyond that of adding to the beauty and harmony of Nature's 

 works, as they similarly urge the colours of the plumage of 

 the birds themselves ; but let us see what an important part 

 the colouring matter of birds' eggs plays in the economy of 

 the birds let us see how their complex and ever-varying 

 colours conform to the subtle influence of Law. The 

 colouring matter of birds' eggs is influenced by the birds' 

 mode of nidification, and is partly subordinated to the colour 

 of the parents' plumage. For convenience of treatment it is 

 advisable to divide birds' eggs into two great classes, quite 

 irrespective of the affinities of the birds themselves, but solely 

 in accordance with the fact of their being coloured or un- 

 coloured, spotted or unspotted. Each of these great groups 

 may be further subdivided into two sub-groups, which will 

 include the exceptional cases in each. 



We will begin with those eggs which display no colouring 

 matter. I think we must start with the very probable supposi- 

 tion that the eggs of the earliest forms of bird-life were white. 

 Colour is a development for protective purposes, and to that 

 cause alone must be ascribed all the wonderful and beautiful 

 diversity of tints with which so many birds' eggs are now 

 adorned. In most birds, where the eggs are hid from sight, 

 either in domed nests or in nests in holes, we never find their 

 eggs exhibiting much colouring matter it is not required, 

 therefore it is not developed. Eggs brought to maturity in 

 such places are mostly pure white or pale blue, and only in 

 the minority of cases more or less faintly spotted. As 



