CHAPTER XII. 



Diseases of the Respiratory System. 



Anatomy and Physiology. 



The respiratory organs of birds are the nasal passages, the 

 pharynx, larynx, trachea, lungs and air sacs. The form and 

 general appearance of the lungs and trachea are ohown in fig. 



12. 



B 



Fig. 12. Lungs of a 

 bird. A, lower sur- 

 face. B, upper sur- 

 face. (After Salmon). 



/'I 







Fig. 13. Right lung 

 of a goose. A, 

 primary branches, 

 b, and b', open- 

 ings into abdomi- 

 nal and thoracic 

 air sacs, c, c, sec- 

 o n d a r y bronchi. 

 (After Owen). 



The respiratory apparatus differs somewhat in structure and 

 function from that of mammals. As in mammals the trachea 

 (wind-pipe) divides into the primary bronchi, one passing to 

 each lung. In birds these bronchi do not divide and subdivide 



