DOUGLAS AND BENEDICT METHODS. 



161 



in the measurements. The respiratory quotient shows a slightly 

 better uniformity with the Tissot apparatus than with the spirometer 

 unit. On the whole, the results indicate that with good subjects it is 

 possible to obtain comparable results in the measurement of the 

 respiratory exchange with both types of apparatus. 



14 15 

 PER CENT Or VARIATION 



13 14 If) 



Fig. 44. — Probability curves for the series of comparison experiments with the spirometer unit 



and the Tissot apparatus. 



The ordinates indicate the percentage of the total number of periods and the abscissse the 

 percentage of variation from the average. 



DOUGLAS RESPIRATION APPARATUS AND BENEDICT RESPIRATION APPARATUS 



(SPIROMETER UNIT). 



Although the Douglas respiration apparatus had not been used in 

 this laboratory for regular respiration experiments, it was deemed 

 advisable to compare the gaseous metabolism as measured by the 

 Douglas method with that measured by the spirometer unit. A de- 

 scription of the Douglas method has been given in a previous section 

 of this report. 1 



For the earlier experiments in the series a bag was purchased which 

 was made from a fairly good grade of rubber and was supplied with a 

 tube leading into it through which air could be introduced. This bag 

 was supposed to have a capacity of 100 liters, but it was found that it 



*8ee p. 67. 



