CHAP. XII 
THE COLOURS OF BIRDS 
243 
food, there is at present no reason to doubt that 
under ordinary circumstances the lipochromes of birds 
are self-produced and not derived. 
Let us first consider the distribution of colour in 
birds. The bright colours are largely, though by 
no means exclusively, confined to the exposed parts 
of the feathers. They may, however, occur on the 
beak, the feet, and legs, the bare patches on the 
head and neck of many birds, and even the parts of 
the body which are covered with feathers, and the 
mouth cavity. The colours in general fall into 
three sets :—Those due to lipochromes, those due to 
the dark melanins, and those which are structural. 
The lipochromes when present tend to be uniformly 
diffused, and are probably always in solution in the 
abundant fats. It is an old observation that the 
intensity of the red colour in the flamingo depends 
upon the amount of oil contained in the feathers. 
Besides occurring in the feathers, bill, feet, etc., lipo¬ 
chromes usually colour the deposits of fat in the 
body and the yolk of the eggs. 
The dark melanin pigments are very widely dis¬ 
tributed in birds as in all Vertebrates. They occur 
in the form of minute amorphous granules in the 
epidermis or the cuticular structures, and not in¬ 
frequently give rise to brilliant structural colour or 
to very elaborate patterns and markings ; in some 
cases they are uniformly distributed and give rise to 
plain gray, brown, black, and related tints. Struc¬ 
tural colours in birds are abundant, and include, in 
addition to all metallic colours, blue, green, some 
yellows, white, and in part the glossy black colours. 
Blue, whether it occurs on feathers as in the jay, or 
