288 Cuculidce. 



than it deserves. Let it be taken for what it is worth, though I 

 think it deserves consideration in connection with the subject 

 before us. 



And now, in support of my opinion, I unhesitatingly assert that 

 the Cuckoo about to lay her egg has no more notion of its 

 colour than any other bird has. The will of the parent has 

 nothing whatever to do with it. I am too ignorant of the process 

 by which the pigment or colouring matter is diffused over the 

 egg, or of the exact moment when it receives that pigment before 

 leaving the oviduct, to be able to show by conclusive reasoning that 

 birds, of whatever species, are wholly passive and unconscious while 

 the colouring of their eggs is going on ; but I venture to assert, 

 without much fear of opposition, that such is the case with 

 all birds, and with the Cuckoo not less than with other species. 



What it is that influences the colouring matter, and produces 

 a blue egg for one species, a brown egg for another, and a reddish 

 egg for a third, I can no more describe than I can account for 

 the varying colours in plumage in the respective species of birds. 

 Whether the colouring process in regard to the egg is influenced 

 in any degree by the kinds of food the bird eats, I do not know ; 

 though that food has an effect on the colour of the plumage of 

 birds I do know; of this the familiar case of the Bullfinch 

 becoming black if fed on hemp-seed is a well-known and sufficient 

 example. 



Next, I submit that in all probability the young of the several 

 species of even our insect-eating Warblers are not fed on precisely 

 the same diet. This in many cases is obvious ; because whereas 

 one species procures its insect-food near the banks of streams or 

 ponds, another in our meadows and gardens, and another in the 

 hedgerows and ditches, these must undoubtedly feed their young 

 on the insects which abound in the districts they severally 

 frequent. Then I think it is not improbable that the same rule 

 holds good in regard to all species of birds. I mean that the 

 Hedge Accentor will feed its young with one kind of food;* the 

 Robin with another, and the Wagtail with a third, and so on 

 throughout the list of foster-parents to which the Cuckoo entrusts 



