RING DOVE 
233 
Dove and the Rock Dove, which also lay perfectly 
white eggs, do breed in holes, as we should expect 
of them ; and the explanation of the white eggs of 
the bush and branch-building Wood Pigeon and 
Turtle Dove is probably this, that they have only 
left their ancestral holes, and taken to their present 
style of building, a short time ago, as time goes in 
science, and have not yet developed the coloured 
and spotted eggs which rightly fit the new situa- 
tion. We thus see one of Nature's processes in a 
state of change and incompleteness, between the 
period, some millions of years ago, when the Wood 
Pigeon and Turtle Dove nested in holes, as their 
relations do still, and the other period some millions 
of years hence, when, if no other causes interrupt 
the process of development, we should expect them 
to produce spotted eggs like those of the Crows, or 
Finches. The extremely rough-and-ready methods 
of nest-building of these two Doves also lend sup- 
port to this explanation of the problem, and are 
themselves explained by it. For the nests of the 
Wood Pigeon and the Turtle Dove, though ex- 
tremely poor affairs for an open situation in trees 
and bushes, would be perfectly adequate and suffi- 
cient as the mere flooring or lining of a snug and 
well-protected hole ; and, as a matter of fact, the 
Rock Dove does make an almost exactly similar 
nest in such a situation So that, as time goes on 
