8 BRITISH BIRDS 



are examples of substances which owe their colour to their 

 structure; and the hues of the bird's feather are produced by a 

 similar kind of structure. Finely ruled lines engraved upon the 

 feather just below a clear and transparent outer skin are responsible 

 for the tints of different colours. But there are many birds whose 

 colours are entirely due to the pigments. The most interesting 

 instance of this in many ways is an African bird, the Touraco. 

 This bird is green for the most part, but the feathers of the wingp 

 are of a magnificent crimson. "When the birds take to the wing 

 this gorgeous colour is displayed ; before, it is concealed by the 

 overlying feathers. The colouring matter can be easily extracted 

 from the wing, and it forms a solution of a splendid crimson as 

 bright as the substance called cochineal, which is the product of an 

 insect. It was once said that this colour could be, and was as a 

 matter of fact, washed out from the wings of the bird during heavy 

 storms of rain, and that when a touraco was shot and fell into the 

 water it stained the water red, not with its blood, but with the dye 

 from its feathers. This is, however, an exaggerated way of putting 

 the fact that even very feebly alkaline water will dissolve out the 

 colour. Some of the yellows of the woodpeckers and the browns 

 and reds of other birds are solely brought about by the presence of 

 pigments. 



In speaking of birds as * feathered songsters ' or as ' feathered 

 bipeds,' we are a little apt to lose sight of the fact that they are also 

 scaly an error which is occasionally rectified by the view of an 

 obtrusive pair of legs belonging to the fowl upon the dinner-table. 

 The legs of birds are nearly always scaly ; there are a few excep- 

 tions or nearly exceptions. For instance, there is a special breed 

 of pigeons with feathered legs ; and the sand-grouse, which makes 

 those remarkable and periodical invasions, has legs which are more 

 covered with feathers than with scales. 



The possession of scales is one of the most striking points of 

 resemblance between birds and reptiles. At first sight it seems to 

 be almost absurd to attempt to draw any parallel between the active, 

 feathered, hot-blooded bird and the scaly, cold-blooded reptile ; yet 

 there are many resemblances, some others of which will be indicated 

 in the following pages. In the meantime we are concerned with 

 the scales. These are flat plates, produced by a horny alteration of 

 the soft underlying skin, which are precisely like those of the lizards 

 and snakes. No other animals possess scales ; those of the 

 armadillo appear to be not unlike the scales of reptiles and birds, 



