12 



COMPARISONS OF RESPIRATORY EXCHANGE. 



Basel, and a spirometer constructed by Jaquet. Mueller valves were 

 used with the spirometer. The results per hour in grams are given 

 in table 3. The author says that the lower results obtained with the 

 spirometer can be explained by the fact that the cutaneous respiration 

 was not taken into account. 



Table 3. — Comparison of the respiratory exchange of one subject with different 

 respiration apparatus {Loeffler). 



It must be noted that none of these comparisons are ideal. The 

 experiments from which the data are drawn were carried out by dif- 

 ferent observers in different places; in one instance the comparison 

 was made of experiments with wholly different groups of subjects. 

 Furthermore, as the observations were not carried out on the same 

 day, the differences in daily metabolism may have played a role, for the 

 variations from day to day may be as high as 30 per cent. 1 



The measurements of the carbon-dioxide elimination may have 

 been affected by two entirely different factors. One, which is purely 

 physiological, is due to differences in the storage of glycogen. An 

 individual with a large store of carbohydrate in the body will give a 

 high respiratory quotient because of the preponderance of carbohy- 

 drate taking part in the daily metabolism and consequently a higher 

 amount of carbon dioxide will be eliminated by such a subject than 

 by one whose metabolism consists largely of the oxidation of fat. 

 The other factor is the mechanics of respiration. If a respiration appa- 

 ratus offers a hindrance to normal respiration, the ventilation of the 

 lungs will be disturbed, with a consequent disturbance of the elimi- 

 nation of carbon dioxide. It is therefore very desirable to conduct the 

 experiments with the various forms of respiration apparatus in such a 

 manner that the only possible difference in the measurement of the res- 

 piratory exchange is due to the difference in the apparatus themselves. 



APPARATUS AND TECHNIQUE USED IN THE PRESENT STUDY. 



As has already been pointed out in the preceding discussion, for a fair 

 comparison of the various methods for determining the respiratory 

 exchange, the experiments with the apparatus compared should be 

 made under conditions as nearly identical as possible. Accordingly 



'Benedict, Journ. Biol. Chem., 1915, 20, p. 291. 



