64 ANIMAL BIOLOGY 



wings and legs. With the exception of the feet, practically 

 the whole of the animal is covered with feathers (Fig. 46). 



FIG. 46. External structure of a bird. 



50. Head. A closer study of a bird shows that from the 

 front part of the head projects a horny structure known as 

 the beak or bill. " Tie a man's hands and arms tightly 

 behind his back, stand him on his feet, and tell him that he 

 must hereafter find and prepare his food, build his house, 

 defend himself from his enemies and perform all the busi- 

 ness of life in such a position, and what a pitiable object he 

 would present ! Yet this is not unlike what birds have to 

 do. Almost every form of vegetable and animal life is used 

 as food by one or another of the species. Birds have most 

 intricately built homes, and their methods of defense are to 

 be numbered by the score ; the care of their delicate plumage 



