ORGANS OF BREATHING. 5f 



In the Eagle, Hawk, Stork, Lark, and other birds in 

 the habit of soaring, the air-cells are very large, particu- 

 larly those in connexion with the wing. On the other 

 hand, in Ostriches, or those birds which either never, or 

 seldom fly, those of the wing are comparatively small ; 

 but as a compensation, it has been remarked, that as 

 great strength as well as lightness is desirable to enable 

 them to run swiftly, their bones are almost all of them, 

 remarkably hollow. Such are some of the advantages, 

 derived from this abundant supply of air. 



We have alluded to the additional warmth possessed 

 by birds, in comparison with other animals, to which 

 this greater quantity of air must essentially conduce. 

 We may here again refer to the Gannet, which, passing 

 so much of its time in the depth of winter, exposed to 

 the severest weather, would, if not provided with addi- 

 tional means of keeping itself warm, often perish from 

 cold ; but having, as we have observed, a power of filling 

 up the space between its flesh and outward skin with 

 air, it is thus furnished with a light, but at the same 

 time admirable coat, which effectually prevents it from 

 feeling the effects of cold, however severe. 



