BIRDS. 



INTRODUCTOEY CHAPTER. 



Birds are tlie spoilt cliildreu of nature — the favourites of creation. 

 Their brilliant plumage often assumes the most resplendent 

 colours. They have the happ}'- privilege of moving in space — now 

 fluttering through the air, hunting the insect which flits from 

 flower to flower ; now soaring high aloft, and swooping upon the 

 victim it has marked for its prey ; now cleaving the atmosphere 

 on rapid wing, and performing journeys of vast extent with great 

 rapidity. Mankind have a profound sympathy with these little 

 winged beings, which charm at once by the elegance of their form, 

 the melody of their song, and the graceful impetuosity of their 

 movements. 



Anatomically speaking, birds are connected with the Mammi- 

 fera by their internal structure. Their skeleton essentially 

 resembles that of the Mammals, the bones being nearly the same, 

 only modified slightly for the purposes of flight. 



In birds there is a double circulation. The heart consists of 

 two moieties, or lobes, known as the auricle and ventricle. It 

 is conical in form, and occupies the anterior part of the thorax, 

 its apex passing between the lobes of the liver ; but there is little 

 perceptible distinction between auricles and ventricles. Their 

 blood is richer in globules than that of the Mammalia, being more 

 thoroughly permeated by air ; the respiratory fimction is also more 

 energetic, from the same cause — in fact, they consume a larger 

 quantity of oxygen, and produce a proportionately greater degree 

 of heat ; for while their lungs are small, and placed in the upper 



