236 



THE KESPIKATOKY SYSTEM 



angles the smaller and smaller bronchi finally end in minute 

 terminal bronchioles which lead through the alveolar ducts to the 

 pulmonary air sacs or alveoli. 



The wall of the largest BRONCHI is similar in structure to that 

 of the trachea, but in bronchial tubes which are two or three divi- 





FlG. 200. A LARGE BRONCHUS OF THE PIG'S LUNG. 



a, pulmonary artery ; 6, pulmonary vein ; c, pulmonary alveoli ; beneath d, a terminal 

 bronchiole with its infundibulum and atrium is seen. Hematein and eosin. Photo, 

 x 10. 



sions removed from the primary bronchi the plates of cartilage are 

 no longer C-shaped, and a complete muscularis mucosae, within the 

 cartilages, forms the outermost boundary of the mucous membrane. 



