88 THE STORY OF BIRD-LIFE. 



then see what an admirable paJdle his modified 

 wing has become, having entirely supplanted the 

 feet for the purpose of propulsion in the water. 

 In the penguin, the feet are stretched out behind 

 quite straight and held motionless, whilst the 

 wings work as rapidly as if the bird were flying 

 through the air. 



Thus the loss of flight may be folio wred by the 

 entire loss of the Avhole wing ; or this organ, 

 whilst undergoing a certain amount of degenera- 

 tion, may be saved, as it were, to perform some 

 new function — such as that of swimming. The 

 loss of the whole wing cannot be regarded as a 

 dead loss to a flightless bird. The amount of 

 nourishment wdiich would be expended in its 

 sustenance is put to the credit of the sustenance 

 of the rest of the body. 



CHAPTER YI. 



COURTSHIP. 



To tell the story of the courtship and lovemaking 

 of the birds, in anything like fulness, would be to 

 undertake a task far too large to be compressed 

 within the limits of these pages. But we can and 

 will take a brief survey of some of its more im- 

 portant features. We venture to think that these 

 will form a surprise, as pleasing as it is great. 

 That they will prove quite a revelation of the 

 hidden life of the bird world. 



With the birds, as with ourselves, there comes, 

 with the period of maturity, that strange indefin- 



