234 HANDBOOK OF BRITISH INLAND BIRDS 
— the inexhaustible time of science — we should ex- 
pect the Wood Pigeon and Turtle Dove gradually 
to learn to build the kind of nest which Nature de- 
mands, as a rule, of birds which build in the more 
open situations which they have chosen. It is worth 
noticing that the Wood Pigeon is still very fond 
of building in the middle of a thick, dark ivy- 
bush, a situation which seems to show a lingering 
preference for its ancient caverns. As to the whole 
subject of the resemblance of eggs to their sur- 
roundings, it will be seen, on examination and reflec- 
tion, that eggs laid in nests which are half-hidden 
and protected by grass, trees, or bushes have only 
a half-protective design — a sort of rough likeness 
to the colours and shadows of the place in which 
they are laid ; while those which are laid quite out 
in the open, on the bare earth or gravel, have 
generally a scheme of colouring which safeguards 
them with far greater accuracy and completeness. 
The eggs of all birds were probably white and un- 
spotted in the beginning, like those of the reptiles 
from which they are descended ; but only those 
birds which nested in good, safe holes could afford 
to go on laying eggs of such a conspicuous appear- 
ance, while the species which bred in more exposed 
situations had to develop patterns of colour. And 
these patterns became more or less thoroughly 
imitative their surroundings in proportion to 
