THE STORY OF THE LUNGS, SKIN AND KIDNEYS 85 



Free movement of the neck is thus permitted, whilst 

 the passage of air to the lungs continues uninterrup- 

 tedly. The heart lies between the lungs (Fig. 25), a 

 situation admirably adapted for the easy maintenance 

 of the close relationship we have already noted to 

 exist between the two organs. The chest is lined 



Fig. 24 .LARYNX OR VOICE Box, TRACHEA 

 AND BRONCHI. 



(7) larynx; (2) windpipe or trachea; (3} 



bronchial tubes or main divisions of windpipe 



in lungs. 



and the lungs covered with a delicate smooth and 

 glistening membrane called the pleura. In the move- 

 ments of the lungs in breathing it is therefore the 

 layer of the pleura covering the lung which moves 

 smoothly on the layer lining the chest. A little 

 fluid secretion is perpetually thrown out between the 



