LUNGS. 



[ 479 ] 



LUNGS. 



Fig. 419. 



Two pulmonary lobules a a, with the air-cells 6 b, 

 and the terminations of the bronchi c c ; from an infant 

 newly born. 



Magnified 25 diameters. 



the outlioes of wliich in adults are also 

 principally mapped out by lines of pigment. 



Fig. 420. 



Outer surface of the lung of a cow, the air-cells of 

 which are injected with wax: a, a, a, air-cells; b, b, 

 boundaries of the (primary) lobules. 



Magnified 30 diameters. 



The lobular structure of tlie lungs is best 

 shown in the lungs of festal animals in- 

 jected from the trachea or bronchi. 



The capillaries of the lungs are extremely 

 minute and very difficult to inject fully; 

 and the finest injection is required for the 

 purpose. 



The capillaries may often be well seen 

 in thin sections of the inflated and dried 

 organs. The altered structure of emphyse- 



matous lungs may also be best shown by 

 this method. 



Fig. 421. 



*.J^® 



l^^-r^^V^ 







.>\:n^ 



Air-cells of a human lung, a, epithelium; 6, fibrous 

 portion, where the walls of several air-cells are con- 

 fluent ; c, thinner walls of several air-cells. 



Magnified 350 diameters. 



Fig. 422. 



Capillaries of the human lung. 



Magnified 60 diameters. 



The epithelium is best seen in sections of 



