290 OUR NATIYE SONGSTERS. 



which it breathes with great rapidity, and imbibes 

 a large quantity. Its bones are made light by 

 cavities, filled with air instead of marrow ; and 

 the feathers admit air into their interstices. The 

 wings of the bird, convex above, and concave 

 below, are moved by most vigorous muscles ; and 

 the downy and feathery covering protects it better 

 than aught else could do, from the sudden and 

 great variations of temperature to which it is 

 exposed, and is at the same time of lightest 

 nature. Every feather has a stem, hollow in part; 

 and the barbs are all studded with lesser barbs, 

 arranged with the gi'eatest skill, and all of so 

 little weight, that a feather has become a very 

 type of lightness. We rarely find fossil bones of 

 birds, and it is because of this lightness, for such 

 as die on the water or fall into it, do not sink into 

 the ground as other objects might do, before they 

 had time to be wholly devoured or decomposed. 

 What wonder that with a system so adapted for 

 inhaling the pure air, and so well suited for motion, 

 the bird should be impatient of repose, and need 

 little sleep ? that it should feel blithe and buoyant, 

 and pour out its full heart in song ? With its free 

 and independent habits, and delicate sensations, 



