INTRODUCTION. 



A bird in all its parts is perfectly adapted for the element in 

 which it moves, and the functions it has to perform. Its frame 

 is formed for lightness and buoyancy, and so constructed as to 

 accelerate its motion in the air. The wings, made of the 

 1'ghtest material, strike the air with, great force ; the tail acts 

 as a rudder, enabling the bird to direct its course. The lungs 

 of a bird are very small, but its body is provided with many 

 air-cells, which may be inflated or emptied at pleasure. By 

 filling these hollow parts with air, a bird may become very- 

 buoyant, and easily sail in the atmosphere. By forcing the 

 air out, the weight of the bird increases, when it can dart 

 down from great hights with astonishing rapidity. With such 

 internal reservoirs of air to draw upon, a bird may fly at great 

 speed through the atmosphere with no inconvenience in 

 breathing, or risk of suffocation. 



The digestive organs of song birds, for the most part, con- 

 sist of cartilaginous stomachs, covered with strong muscles. 

 These organs are given to birds, the principal food of which 

 is grain and seeds of various kinds, or other hard substances 

 that require much friction to divide. To aid in this process, 

 gravel is used. The small stones taken into the gizzard to 

 assist in the process of grinding the food, are retained until 

 they have become polished, and, therefore, less useful. By 

 the time the food has passed thrc agh the third stomach, it 

 is completely triturated, and prepared for the operation of 

 the gastric juices. Content with the seeds of plants, with 

 fruits, insects, and worms, the principal attention of grami- 

 nivorous birds is directed to procuring food, hatching and 

 rearing their offspring, and eluding the snares of men and 

 the attacks of predaceous animals. 



PLUMAGE OF BIRDS. 



There is hardly anything more wonderful in nature than 

 the structure of a simple feather. It is graceful in outline, 

 and unique in form, soft and delicate in texture, and per- 

 fectly adapted to the use for which it was designed. An 

 amazing difference exists between feathers of different birds, 

 from the stout quill of the buzzard's or eagle's wing, to the i 



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