204 



COMPARISONS OF RESPIRATORY EXCHANGE. 



The differences between the average results obtained in each experi- 

 ment for the two types of valves are given in table 38, the values for 

 the Tissot valves being used as the basis of calculation. Considering 

 the individual comparisons, it will be seen that the variations are not 

 very large and are usually in one direction. For example, with 

 W. J. T., two experiments show that the respiratory exchange with the 

 Mueller valves is somewhat higher than with the Tissot valves, while 

 the respiratory quotient is practically the same. The average respira- 

 tion-rate, however, is lower with the Mueller valves; in two instances 

 the respiration-rate with the Mueller valves is nearer the normal rate of 

 19 to 20 per minute than with the Tissot valves. The volume per 

 respiration is noticeably higher with the Mueller valves. A peculiarity 

 in the breathing of this subject was that the rate gradually increased 

 during the morning and unfortunately, in the first comparison experi- 

 ment with him, the periods with the two types of valves were not 

 alternated. It is therefore somewhat difficult to decide whether the 



TABLE 38. Variations of average results obtained with Mueller valves from the average 



results obtained with Tissot valves. 



decreased metabolism shown by this subject with the Tissot valves is 

 due to the valves themselves or to the fact that the subject became 

 quieter as the experiment continued, with a consequent lowering of 

 metabolism in the latter part of the morning. The first two compari- 

 son experiments indicate that the respiratory exchange was higher with 

 the Mueller valves, while on April 26 the metabolism was practically 

 the same with both types of valves. 



On the other hand, the results of the experiments with J. J. G. indi- 

 cate that the respiratory exchange is lower with the Mueller valves 

 than with the Tissot valves, although the differences in the respiratory 

 exchange with the two types of valves are not very large. In two cases 

 the normal respiration-rate for this subject was approached by the 

 respiration-rate with the Tissot valves. The comparison experiment 

 with J. H. H. shows a decidedly different value in the amount of carbon- 

 dioxide elimination, that with the Mueller valves being very much 



