194 



COMPARISONS OF RESPIRATORY EXCHANGE. 



with the glass nosepieces, when it varied from 61 to 69 beats per minute. 

 Subject stated he was not asleep in this period. Respiration-rate varied, 

 particularly in the first three periods. Average barometric pressure, 766.4 

 mm.; average temperature of air in the apparatus, 21° C. 



DISCUSSION OF RESULTS. 



The results of the two experiments in this comparison are given in 

 table 34. The average results show no marked difference in the respi- 

 ratory exchange for the two types of nosepieces. These experiments 

 were made in connection with other work and the number of compari- 



Table 34. — Respiratory exchange in comparison experiments with glass and pneumatic nose- 

 pieces — Benedict respiration apparatus (spirometer unit). (Without food.) 



sons is so limited that no very definite conclusions can be drawn from 

 them. A calculation of the uniformity in the results has been made, 

 but the number of periods was too small to permit the plotting of curves. 

 The most marked difference is shown in the total ventilation, which is 

 more uniform with the glass nosepieces than with the pneumatic 

 nosepieces. The other factors, carbon-dioxide elimination, oxygen 

 consumption, etc., have practically the same degree of uniformity in 

 both types of breathing. In one experiment the subject stated that 

 it was easier breathing through glass nosepieces than through pneumatic 

 nosepieces. The question as to which type of nosepieces is the more 

 advisable to use is discussed in a later section. 



