BIRDS 111 



courtship in birds, ideas which prevent the matter being 

 seen in its true light. The hen-bird is supposed to choose 

 one male from a number because he has the most beautiful 

 plumage, and the male is supposed to spread out his special 

 feathers because he knows they are beautiful. This is 

 anthropomorphism; there is no reason to suppose that 

 aesthetic ideas exist in either male or female bird. The male, 

 when in the beginning he is quite similar to the female, erects 

 and moves some part of his plumage under the influence of sexual 

 excitement. When he fights he erects his neck feathers 

 partly to ward off the blows of his enemy's beak. When he 

 courts he erects or vibrates other feathers. Nearly all the 

 feathers of a bird can be voluntarily moved or erected. The 

 particular feathers which the male moves when sexually 

 excited depends on the peculiarities of the species previously 

 evolved, and its habits in ordinary life. Thus a flying bird 

 will fly about when courting, like the humming-bird, a ground 

 bird will strut like the peacock. The male, when he has no 

 voice like that of a singing bird, moves about and agitates his 

 feathers, partly because his excitement finds vent that way, 

 partly to show the female what he desires. Thus for each 

 species particular gestures and erection of particular feathers 

 become habitual, and if the male bird, from his polygamous 

 habits and entire freedom from the cares of incubation or nurs- 

 ing, devotes himself with increasing energy to the practice of 

 these special gestures and movements, the result will in course 

 of time be visible in the corresponding excessive growth and 

 development of the feathers and organs stimulated. 



The classification of birds is a very difficult and complicated 

 subject, and considerable progress and improvement has been 

 made in it in recent years; so that modern systems differ very 

 greatly from those formerly employed. They also differ to 

 a great extent from one another. My present subject, how- 

 ever, has nothing to do with difficult or disputed points of 



