196 



ANATOMY OF THE DOMESTIC FOWL 



neys, and laterally to the juncture of the vertebral with the sternal 

 portions of the ribs. They present two faces, a superior convex and 

 an inferior concave; two borders, an external and an internal; and two 

 extremities, an anterior and a posterior (Fig. 61). The convex sur- 



C 



Fig. 61. — The lung; 



A . The outer surface of one lung. Note the flattened oval shape. It is not 

 divided into lobes, i, The bronchus, z. Primary tubules showing openings 

 leading from the primary tubules to the secondary tubules. 3, Openings of two 

 of the large tubes into the diaphragmatic and abdominal air-sacs. 



B. Sectioned surface of lung, i, Secondary tubules, z. Tertiary tubules. 

 3, Interlacing capillaries and air cells. 



C. I, Cavity of tubule, i!, Its lining membrane supporting blood-vessels with 

 large areola. 3, Perforations in the membrane at the orifices of the lobular 

 passage. 4, Interlobular space containing the terminal branches of the pulmo- 

 nary vessels supplying the capillary plexus, 5, 5, to the meshes of which air gets 

 access by the lobular passage. 



face is also called the dorsal, costal, or superior face. It is moulded 

 on the walls of the thorax and occupies a part of the intercostal 

 space, pushing the intercostal muscles outward. When the surface 

 of the lung is examined it is seen to be furrowed where the ribs 

 pressed during hfe. These furrows are as deep as the ribs are 



