v RESPIRATION 51 



This is about thirty cubic inches and is called the tidal 

 air. 



We can also measure the amount of air that we can 

 force out by the most violent effort after an ordinary 

 expiration. This is about one hundred cubic inches and 

 is known as the reserve, or supplemental air. After an 

 ordinary inspiration we can inhale about one hundred 



FIG. 24. Testing the lungs on the spirometer (Zuppke). 



cubic inches more. This we call the complemental air. 

 Thus after a forced inspiration we can exhale the com- 

 plemental, the tidal, and the supplemental air, amount- 

 ing in all to about two hundred and thirty cubic inches. 

 This is called the vital capacity, or, simply, the lung 

 capacity. But after a forced expiration there still 

 remains in the lungs about one hundred cubic inches 

 which cannot be expelled by any possible means. This 



