266 



THICK WIND. — BROKEIS^ WIND. 



a 



The annexed diagram will clearly illustrate the phenomena 

 in question : — Let the reader suppose the tube a to be the 

 windpipe, and the small tubes Hh the right and left bronchial 

 tubes passing into cc, the right and left lungs : dd to be the 



outer or investing membrane 

 of the"lungs, and being in close 

 contact with the same at every 

 part of their surface ; while 

 eeeeeesLYO dotted lines to show 

 the direction of the lunge cc, 

 seen beneath this outer or in- 

 vesting membrane. 



Now the lungs, as most in- 

 telligent people are aware, are 

 light, spongy bodies, containing 

 innumerable passages through 

 which the air freely circulates, 

 and by means of which the 

 purification of the bood within 

 the pulmonary organs is con- 

 stantly affected. The lungs are 

 also highly elastic bodies, and 

 their outer or investing mem- 

 brane (membrane dd), is like- 

 wise so constituted as to be 

 readily adapted to the varying 

 size of the lungs, arising from 

 the inspiration and the expira- 

 tion of the air. To the reflective 

 reader it will be evident that 

 air passingdown the tube a, and 

 entering the lungs through the 



Fiff. 19. 



A diagram showing the position of 

 the lungs and their outer or investing 

 membrane. 



a The trachea. 

 hb The right and left bronchial 



tubes going to 

 cc The right and left lungs. 

 dd The outer or investing mem- 

 brane of the lungs, 

 ceeeee Dotted lines showing the direc- 

 tion of the lungs cc beneath 

 their investing membrane. 



