548 



EFFECT OF SUSPENDED RESPIRATION ON COMPOSITION OF ALVEOLAR AIR, 



made from a bag containing air mixed with a percentage of carbon dioxide 

 gi'eater than the final values expected, so that the percentages at first fell during 

 the experiment instead of rising as before. 



Table 2. 



Alveolar carbon dioxide content after holding expired air in lungs under 

 normal pressure. Initial inspiration from mixture of air with carbon dioxide. 



Number of 

 inspiration 



Alveolar carbon dioxide content 



Expt. 4 I Expt. 5 



Percent. Tension | Percent. Tension 



50.3 



10.71 



77.1 



48.5 



7.16 



51.6 



48.9 



7.17 



51.6 



48.7 



6.75 



48.6 



48.9 



6.86 



49.4 





6.64 



47.6 





6.72 



48.4 



The above figures show that after the last four inspirations of each experi- 

 ment approximate constancy had been reached. The mean fig-ures for this period 

 are 6.76 % or 48.7 mm. Hg. These figures are within 0.05 % or 0.2 mm. Hg. 

 of the mean figures for Table 1, and are very close to those of the previous 

 exijeriments. 



From the above two series of figures it will be seen that the average final 

 value reached by the alveolar carbon dioxide, when the breath is held under nor- 

 mal pressure, is practically the same, whether the final value is approached from 

 above or below, and that the mean final values for the two sets of experiments, 

 6.78 % or 48.9 mm. Hg, are very close to the final values of 6.7 % or 48.5 

 mm. Hg indicated by the author's previous work. 



In Table 3 are shown the variations of the alveolar carbon dioxide content 

 when successive inspirations' are made from a bag as described, and held in the 

 lungs under negative pressure. The initial inspiration in each ease was made 

 from the atmosphere. 



Table 3. 

 Alveolar carbon dioxide content after holding expired air in lungs under 

 negative pressure. Initial inspiration from atmosphere. 



Number of 

 inspiration 



Alveolar carbon dioxide content 



Expt. 6 I Expt. 7 I Expt. 8 



Percent. Tension | Percent. Tension | Percent. Tension 



1 



5.35 



38.4 



5 17 



37.5 



5.28 



37. 2 



2 



6.67 



47 8 



6.76 



49.0 



6.48 



46.5 



3 



6.87 



49.3 



7.03 



51.0 



7.04 



50.5 



4 



6-72 



48.2 





51.6 



6.93 



49.7 



5 



7.18 



51.5 



7.02 



50. r 



7.00 



50.3 



6 



7.11 



51.1 



7.05 



51.1 



6.80 



48.8 



7 



7.03 



50.4 



7.18 



52.0 



6.85 



49.2 



The figures in this Table show that approximate constancy of the alveolar 

 carbon dioxide was attained during the last five inspirations of each experiment. 

 The average final value reached for the three experiments is 7.00 % or 50.4 mm. 

 Hg. This value is only about 0.2 % or 1.5 mm. Hg higher than the mean 

 final values for the experiments in Tables 1 and 2, and those found when the 

 breath was held under normal pressures in the former experiments. It is very 

 much lower than the highest values reached when the breath vs'as held under 



