ORDER ACCIPITRES. 97 



more solid, fibrous, and compact, than in the flabby, and in- 

 dolent inhabitants of stagnant and muddy waters. Nay, even 

 man himself is not exempted from these local influences. He 

 becomes lax of fibre, corpulent, and dull on the marshy plain 

 and in the humid valley ; light, lively, muscular, and energetic 

 in the bracing breezes of the highland and the mountain. 



The air, then, must be the most influential element upon the 

 birds, which are perpetually immersed in this vast atmospheric 

 ocean which surrounds our globe. Their whole organization 

 is penetrated by it, as a sponge imbibes water. They have 

 immense lungs, adhering to the ribs, provided with aerial sacs, 

 insinuating themselves into the abdomen. Their bones, cellu- 

 lar texture, feathers — in short, all parts of their system, admit 

 more or less air into their interstices. The sanguine system 

 being thus in perpetual contact with the air, it is easy to ima- 

 gine that the oxygenation of the blood must be more powerful 

 and complete in birds than in any other animal. The respira- 

 tion of the bird must be a combustion more ardent and rapid 

 than ours. In fact, it may be considered a sort of fever, ana- 

 logous to that incident to phthisical subjects, with this differ- 

 ence, that, instead of consuming the body, it warms and ani- 

 mates it with redoubled energy. It constitutes the predomi- 

 nant function of the economy of the bird, which is altogether 

 proportioned to this peculiar source of vital energy. A slight 

 consideration of the constitution of birds will prove this. Their 

 flesh is dry and fibrous, their muscles exceedingly contractile 

 and robust, their disposition lively and impetuous. They are 

 ardent in the sexual intercourse, furious in combat, wild, irri- 

 table, and in perpetual motion. They sleep little, and eat much- 

 They seem to have received from nature stronger sensations, 

 more vital force and activity than other animals, for they live a 

 very long time, and are yet of a temperament extremely warm. 

 Quadrupeds are of a colder and more moderately-tempered 

 constitution. They have neither the activity, ardour, lascivi- 

 ousness, nor vehemence of disposition discernible in all the 



Vol. VI. H 



