78 THE STRUCTURE AND LIFE OF BIRDS chap. 



Breathing Apparatus and Pneumatic Bones. 



A bird's breathing apparatus is of the first order. 

 When a lark is rising, his wings are beating at the 

 rate of quite two hundred strokes per minute, probably 

 much faster. And yet all the while he sings as if he 

 were making no great muscular effort. I recommend 

 any one who does not appreciate the marvel of this to 

 try to run up hill and sing or shout at the same time. 

 Of all those who make this experiment we may quote 

 what Vergil says of the Greek ghosts in Hades, who 

 try to raise their war-cry when yEneas appears : — 



Inceptus clamor frustratur hiantes. 



On the floor of the mouth just behind the tongue is 

 the glottis or opening into the trachea or windpipe, 

 a tube formed of rings of bone and gristle which runs 

 along the neck to its base, where it divides into two 

 bronchi, which lead, one to the right, the other to the 

 left lung. The epiglottis, which springs from the 

 anterior end of the glottis, and the function of which 

 in mammals is to close the opening during the process 

 of swallowing, is very little, if at all, developed in 

 birds. Apparently the edges of the larynx, the name 

 given to the upper end of the trachea, meet so exactly 

 that no epiglottis or lid to the glottis is necessary. 

 The larynx has no vocal chords as in mammals, hence 

 it cannot produce voice, but only raise or lower a note 

 by bringing together or separating the stiff margins of 

 the glottis. The organ of voice is the lower larynx 

 or syrinx, an organ found in no other class of animals, 



