532 ]Mr. C. F. M. Swynnertmi on 



fighting parents — or any other special protection that we can 

 see, unless it shonld be contained within themselves — Culiiis 

 striatus, to take one example out of several. Hoav account 

 for the survival of these and the pigmentation of the others? 

 It would seem that the first must possess some deFence — 

 some counteragent to conspicuousness — that we have over- 

 looked, while the other class of case suggests that concealment 

 may not be the only function of coloration in birds' eggs, 

 though the pigmentation might in some cases be explained 

 away as having unnecessarily outlived a period in which 

 concealment by colour^ and not its present defence, was the 

 species' special protection. 



Other points are overlooked in Wallace's explanation. It 

 is the nest or nesting-hole, not the egg;, of nearly all 

 arboreal species that the enemy will specially look for and 

 usually first detect. Having found it, he will not rest 

 contented with trying " to discover from beneath whether 

 there are eggs in the nest or not." If he is a natural enemy 

 he will look in. And the nests of quite a number of species, 

 as also many nesting- holes, tend to be, to a greater or lesser 

 extent, conspicuous (especially in relation to the close search 

 of an enemy), even when neither inaccessible nor the 

 property of formidable owners. In any case, having regard 

 to the habits of enemies, the line is drawn in the wrong 

 place as between white eggs and all the rest. For numerous 

 coloured eggs are also, as 1 wrote four years ago, '' in brilliant 

 contrast to the nests they lie in." 



Finally, the argument that the eggs of most small birds 

 lie in suri'oundings (of complex lights and shadows) that are 

 capable of concealing objects of any colour might, indeed, 

 account for the survival of coloured eggs, and even for the 

 fact of their pigmentation, but it will not account for their 

 specific coloration — for its diversity and for that quality of 

 striking, even brilliant, distinctiveness which is so marked a 

 characteristic of tlie eggs of birds. 



To sum up, not only a number of diflicult cnses are left 

 unexplained, but also the very thing which most requires an 

 explanation. 



