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 
Fic. 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 
