136 



ELEMENTARY PHYSIOLOGY 



pleura is practically oblitei-ated, that layer of the pleura 

 which covers the lung being in close contact with that 

 whiqh lines the wall of the chest ; but if a small opening 



Fio. 41. — Diagram of the Thorax showing the Position of the Heart 



AND Lungs. 



1-12, ribs ; 11-12, floating ribs ; .t, sternum ; r, rib ; c.c, costal cartilages ; 



c, clavicle ; I, lungs ; a, apex of heart ; peric. pericardium, cut edge. 



be made into the pleura, the lung at once shrinks to a com- 

 paratively small size, and thus develops a great cavity 

 between the two layers of the pleura. If a pipe be now 

 fitted into the bronchus, and air blown through it, the 



