XXVill INTRODUCTION. 
uniform and protective tint were their conditions of life to demand it; 
birds laying eggs unadapted in colour to their changed conditions of life 
would have small chance of transmitting those injurious colours to pos- 
terity, would soon die out completely; and the birds that laid eggs most 
suitable to the changed conditions and in harmony with them would in- 
crease and multiply, and the colours on their eggs be preserved. This, I 
believe, is how all eggs have got their beautiful tints, and how they are 
preserved or changed as circumstances arise. 
Again, the young birds of many species absolutely depend for safety on 
the colour of their down. The Lapwing is arrayed in tints that put us in 
mind of the tropics; the sexes are alike; yet they build an open nest on 
the bleak common, moor, or pasture, where sometimes not a shrub or 
heath-tuft affords a haven of safety. Both birds lack weapons of defence ; 
but note how the safety of their young is insured: their sombre plumage 
of brown effectually conceals them from view. Upon the least alarm the 
brightly-coloured parents leave their helpless young, who instantly crouch 
to the ground and remain motionless ; their colour so closely harmonizes 
with surrounding tints as to hide them effectually from the enemy that 
menaces them. The young of the Game Birds, all the Sandpipers, and 
many sea-birds might also be given as instances, all of which (where the 
parents’ plumage is conspicuous and dangerous to the welfare of their 
eges or young, and which nest in an open site) have young of protective 
tints. As our last group we notice 
Spotted eggs laid in covered nests.—As we found the anomaly of white 
eggs in open nests, so we also find that of spotted and highly-coloured 
eges in covered nests. We will first notice a few instances amongst 
British birds. We take as our first example the Jackdaw, whose eggs 
are spotted and coloured in a remarkable manner, considering they are 
laid in a covered nest. The Chough is another instance, and the Magpie 
a third. I am inclined to believe that ‘these three birds have changed 
the form or position of their nest from an open to a covered one, and the 
eggs are consequently gradually losing their colours. The eggs of the 
birds just noticed are generally much paler than the eggs of the Crows 
laying in open nests, and they seem slowly reverting to a colourless type. 
When once any particular development ceases to be of any service, its 
tendency is gradually to die out; and this, I think, is the reason that so 
many birds nesting in covered sites lay eggs only slightly spotted, or, as in 
many cases, when compared with the eggs of the family. of birds to which 
they belong, show a marked decrease of coloration. The Robin’s eggs, as 
compared with those of its ally the Bluethroat (Hrithacus cerulecula), 
furnish another instance. The Robin’s nest is well concealed and often 
built in holes, and its eggs are often white or only faintly spotted; the Blue- 
