THE ANATOMY OF A BIBD 7 



feminine adornment. As concerns its feathers, this bird is absolutely 

 white, but other parts of the body are black. A bird that is purely 

 white, not only in the feathers but in the legs and beak, is called an 

 albino. This state of affairs is not commonly met with, but it 

 sometimes occurs ; everybody has heard of that contradiction in 

 terms, but actually existent creature, the * white blackbird.' In all 

 these cases there is something wanting in the feather ; for white is 

 not a colour — it is the negation of colour, and is due in nearly every 

 case to the scattering of the rays of light which fall upon the 

 object. This happens when the material that is coloured white is 

 broken up into minute fragments separated by air. The froth of 

 the sea or of a brimming tankard is simply due to the entangling of 

 bubbles of air, which scatter the rays of light. The stems of the 

 feathers contain bubbles of air, which bring about a like effect. But 

 the majority of birds are coloured, and, as a rule, perhaps, brightl;y 

 coloured. We have not in this country many birds which can 

 compare with the gaudy parrots of the East ; but brilliancy of hue 

 is by no means wanting in the birds of this and of other countries 

 which enjoy a temperate climate. It used to be said that brilliancy of 

 colour was a characteristic of the tropics. But it is always pointed out> 

 by way of a refutation of that statement, that the Golden Pheasant 

 of China is as gorgeous a bird as any which exists. There are few 

 smaU birds which are really more brilliant in hue than our YeUow- 

 hammers, Goldfinches, Bullfinches, and some others. We have, it 

 is true, nothing to seriously compete with the Humming-birds; 

 but these birds are found not only in the tropical forests of Brazil, 

 but also in North America and upon the snowy summits of 

 the Andes, and can therefore hardly be used as an instance of the 

 exclusive restriction of brilliant colour to a tropical climate. 



The hues of the feathers are due to two causes. In every case 

 where there is colour at all the feathers contain a certain amount 

 of dye, or pigment, as it is more usually termed ; this pigment may 

 be alone responsible for the colour of the feather, or it may be only a 

 part of the cause. If the bright blue feather from a Macaw's wing 

 be roughly pressed so as to injure the surface, the blue colour will 

 disappear from the rubbed place, and will be apparently replaced 

 by a brownish black. The reason for this is that the blue colour is 

 the result of the actual structure of the feather, which requires the 

 underlying black pigment for its manifestation. The crushing 

 destroys that structure and leaves only the dark pigment. The 

 brilliant and varying hues of the soap-bubble and of mother-of-pearf 



