PURPOSE AND PLAN OF RESEARCH. 39 



periods of observation. That at times inconceivably low respiratory 

 quotients are found among the data is not surprising. The difficulties 

 of determining accurately the exact temperature of the air in the appa- 

 ratus, particularly when the infant is restless, needs no special emphasis. 

 Similarly, the equalization of humidity throughout the chamber with no 

 specific ventilation other than that supplied by the air-current likewise 

 presents technical difficulties. The results as a whole are, we believe, 

 accurate and may be accepted without question. It seems fitting, 

 therefore, to present the data exactly as recorded, even though occa- 

 sionally there may be anomalous differences in the values, rather than 

 to attempt an arbitrary selection which might favor our interpretation 

 of the results. While we have given our data completely, without 

 selection and without reservation, the fact should be emphasized that 

 individual quotients must not be interpreted as significant. It was 

 our purpose to collect such a large mass of results that the general 

 picture of both the character and the amount of the metabolism during 

 the first week of post-natal life would be perfectly defined and clear. 



METHOD OF COMPUTATION. 



The details of the experimental routine and of the technique may be 

 found in the publication describing our earlier study. 1 As it appears 

 to be difficult for certain writers to understand the method of comput- 

 ing the results obtained in observations of this character, it seems desir- 

 able to describe our method of calculation somewhat more fully than 

 has previously been done. 



In the determination of the respiratory exchange by an apparatus of 

 the type we employed, it is obvious that the carbon-dioxide output in 

 short periods may be determined more exactly than the oxygen intake. 

 The residual amount of carbon dioxide in the chamber remains constant 

 from period to period, the mechanism supplying the purified air being 

 so adjusted as to replace the air in the chamber some 15 times during 

 a 30-minute period. On the other hand, the determination of the 

 oxygen consumption involves the calculation of the volume of air 

 residual in the chamber at the end of each period. This calculation 

 requires an exact knowledge of the average temperature and the degree 

 of humidity of the air at the end of each period of measurement. As 

 has already been pointed out, the determination of these factors 

 presents great technical difficulties. Since the longer the period of 

 measurement the less the errors influence the results, it has been our 

 custom to measure the carbon dioxide in 30-minute periods, with, so 

 far as possible, complete muscular repose on the part of the infant, and 

 to calculate the oxygen intake only once for the entire time that the 

 child remains in the respiration chamber. It may reasonably be 

 assumed that differences in the muscular activity, especially with the 



'Benedict and Talbot, Carnegie Inst. Wash. Pub. No. 201, 1914, p. 31. 



