200 Major R. F. Meiklejolin on the [Ibis, 



All the facts in the problem are very conflicting, and only 

 the following general rules can be stated : — 



(a) Birds nesting in holes, as a rule, lay wliite eggs. (The 



converse, however, that all birds laying white eggs 

 nest in holes is by no means so true.) 



(b) When the plumage of the female harmonizes with the 



surroundings of the nest, the eggs have a protective 

 coloration, and this is usually the case with birds 

 nesting on the ground, 



(c) Where both sexes are brightly coloured the eggs are 



usually laid in concealed places and are not hand- 

 somely coloured. 

 {d) Many species laying whitish eggs in places exposed to 

 view cover them over when leaving the nest. 



It seems very doubtful if the problem of egg-coloration 

 will ever be solved, and it may be that food, climate, and 

 " strain " all exercise an influence, as is probably the case 

 in the human race. It might throw some light on this if 

 we knew whether clutches of a given species, taken in high 

 latitudes or altitudes, showed any constant variation from 

 others taken in more southern climes. It seems possible 

 that the process of evolution and the change in the nesting- 

 habits of many species owing to the changing conditions of 

 civilization would produce varying types of egg-coloration, 

 while the law of adaptation would ruthlessly eliminate any 

 progression beyond a certain limit, and, consequently, 

 variations in type would persist so long as they did not 

 contravene this law. Further, such individuals or families 

 as laid eggs less well adapted in colour to the requirements 

 of protection or only suitable to certain localities, would 

 remain in a minority, as is perhaps the case with those 

 individual Blackcaps, Rock-Pipits, and other birds which 

 lay eggs of a rufous or distinct type. 



But in the case of the Cuckoo, where there is a large 

 choice in nesting localities and a wide range in suitable egg- 

 coloration, a greater number of families laying differently 

 coloured eggs than in other species would have survived. 



