364 



THE RESPIRATION 



Fig. 131. Curves showing variations in alveolar gas tensions after forced breathing for two 

 minutes. Thin line O 2 tension; thick line CO 2 tension. Double line normal alveolar 

 COa tension. Dotted line shows the alveolar CC>2 tension at which breathing would recommence 

 at the end of apnea with the alveolar O 2 pressures shown by the thin line. The actual breathing 

 is indicated at the lower part of the figure. It is periodic to start with. (From Douglas and 

 Haldane.) 



