54 The Bird 



probably ever given a thought to the colours themselves 

 Why is that feather blue? Why because it is blue! 



There are two principal ways in which colours are 

 produced in feathers: first, when a real colour-pigment 

 is present, and again when the structure of the feather is 

 more or less like miniature prisms in shape, breaking up 



FIG. 36. Young Brown Pelicans in the downy plumage. 1/6 natural size. 



the rays rainbow-like into the iridescence of the spec- 

 trum. In the case of almost all the beauties of Nature, 

 the more closely we examine them, the more beautiful 

 they become. But this is not true of the iridescent 

 colours of birds such as hummingbirds, unless we con- 

 sider the structure. The colour itself disappears under 

 the microscope, and only gray or black tints are seen. 

 The black, red, brown, and yellow colours of feathers 



