DISEASKS OF POULTRY. 



27 



ratel}' molcbd to the inec[ualities of the riljs and the 

 spaces between the ribs. 



Notwithstanding these resemblances to the sluggish 

 cold-blooded animals, the bird's l^reathing apparatus 

 is of the highest order of excellence, and wonderfull}' 



effective. The lungs are 

 comparatively small and 

 have little elasticity, but 

 there is a compensation for 

 these features in the free 

 communication with the 

 si)acious air sacs which 

 contain an abundant suppl}' 

 of air. 



The upi')er opening of the 

 tr.;chea or windpipe is on 

 the floor of the mouth just 

 behind the tongue. The 

 larynx at the beginning of 

 the windpipe, which is such 

 a perfect structure in the 

 higher mammals, is in birds 

 only slightly developed. 

 The edges of the larynx ap - 

 pear to close together so 

 ])erfectl3' that no epiglottis 

 or lid is necessary. There 

 are no vocal cords in the 

 lar)'nx as in mammals, and 

 therefore this organ can not 

 produce voice, and it only 

 raises or lowers a note by bringing together or separat- 

 ing the stiff margins of the opening. The true organ 

 of voice in l)irds is the lowerlarynx or syrinx, which is 



Fig. 1.— Lutigrs of a Bird. 



A. — Lower Surface. 

 B. — Upper Surface. 



