THE LUNGS. 



363 



a tabular bronchial tube or bronchiole or ultimate bronchial tube, 

 and on one side dilatations exist, air-cells or pulmonary alveoli. 



Respiratory 

 bronchiole. 



Alveolar duct. 



Artery. 



Lung- tissue. 



Bronchiole. 



Fio. 203. 



Lung-tissue. 



FIG. 204. 



FIGS. 203 and 204. Two sections of cat's lung: Fig. 203, X 52; Fig. 204, X 35 

 (Bohm and Davidoff). 



These increase in number, and, although at first limited to one side 

 of each bronchiole, they subsequently surround the tube, and the 



