6 



less rapid by an expelled current of air. But in insects, sound 

 is produced by a very different arrangement, namely, by the 

 friction of certain string-like structures in the wings or in some 

 cases on the legs, against certain plates or membranes, which 

 are often stretched aci'oss a cavity situated on the side of the 

 body, the whole resembling in general character and principle 

 our various stringed instruments. Besides these more common 

 sources of sound, the wings are often variously used by birds for 

 the production of different kinds of sound, and in these the 

 feathers are often curiously modified to serve a like purpose. 



Now, we know that nearly all the characters, proceedings, 

 and properties of animals have reference to the sti'uggle for 

 existence, and are useful to them either in procuring food or as a 

 means of defence, and that it is a distinct advantage to them 

 to acquire or bring to perfection certain characters or organs ; 

 and the vocal organs or other means of producing sound 

 certainly are of use to them in this respect, and so come 

 within the operation of the law of natural selection. This 

 applies to the cries and call notes of most animals, 

 which serve, as I have already said, as a means of 

 communication or of recognition between communities and 

 individuals or as warnings against danger. But the case 

 appears different in regard to their more strictly musical per- 

 formances. And here a remarkable fact appears to furnish a 

 clue to the question of the use and purpose of animal music, 

 whether vocal or instrumental. We find, namely, that in most 

 animals, especially birds and insects, the possession of musical 

 powers is limited to the male, and further that these powers 

 are actively exercised by the male exclusively during the 

 season of courtship and mating. This would indicate that the 

 employment of music by animals is, often at all events, of a 

 sexual character, and serves to charm and attract the female, and 

 numerous observations show that this is so. And very often 

 animals, notably birds, combine for this purpose music with re- 

 markable gestures and antics and regular dances ; as witness the 

 performances of various species of gallinaceous birds, — the 

 capercailzie, blackcock, grouse, jungle fowl, and others. I have 

 seen in India, in an open spot in the midst of a dense jungle, a 

 single peahen surrounded by a circle of 15 to 20 admiring pea- 

 cocks, in full and magnificent plumage, with their glorious tails 

 erect and displayed to the fullest exteut. These kept up a chorus 

 of loud and energetic screams, all the while dancing and leaping 

 around the lady, who, though apparently wholly indifferent to 

 these attentions and calmly pecking about in the grass for worms, 

 was no doubt perfectly conscious all the while of being the 

 object and centre of so much homage. In their case the end and 

 issue of their performance were lost, for, becoming conscious by 



