32 PHYSIOLOGY OF THE NEW-BORN INFANT. 



DISCUSSION OF HASSELBALCH'S RESEARCH. 



We consider it peculiarly unfortunate that in our two earlier publica- 

 tions reference to Hasselbalch's research and to his striking conclusions 

 was inadvertently omitted, and although at that time we were unable 

 to comment intelligently upon the results or make a satisfactory 

 abstract of them, since there were some difficulties in the translation, 

 nevertheless it would have been desirable to call attention earlier to 

 the existence of this wholly remarkable piece of research upon infant 

 metabolism. Although the study was made 11 years ago, the same 

 degree of care and nicety of technique which has characterized Hassel- 

 balch's subsequent observations is apparent in this research. It is 

 obvious that we have here for the first time quantitative measurements 

 of the gaseous metabolism of infants by a study of the carbon-dioxide 

 increment and oxygen deficit in the ventilating current of air. It is an 

 interesting fact, which should certainly be pointed out, that the appa- 

 ratus used by Hasselbalch for this study embodied the same principle 

 as the Jaquet 1 apparatus, and, indeed, both forms of apparatus were 

 described in the same year, thus proving independent simultaneous 

 development. 



Of particular importance in studying the respiratory exchange is a 

 special appreciation of the significance of the difficulties of determining 

 the oxygen in any gaseous mixture, even in ordinary atmospheric air. 

 Researches in the Nutrition Laboratory have shown that the external 

 air is of absolutely constant composition, irrespective of seasons, wind 

 direction, weather conditions, barometric pressure, and altitude. 2 

 Consequently it can be assumed that any gas-analysis apparatus which 

 fails to give constant values for the oxygen content of the atmospheric 

 air may be considered on this a priori evidence as being an inaccurate 

 apparatus, or the technique is at fault. 



It is, furthermore, obvious that the greater the carbon-dioxide incre- 

 ment and the greater the oxygen deficit in the ventilating current of air, 

 the less the analytical errors will influence the calculation of the respira- 

 tory quotient. It has been frequently pointed out that those using 

 the Jaquet method are too often inclined so to adjust the ventilating 

 air-current as to have a minimum carbon-dioxide increase and an 

 equivalent oxygen deficit. When this carbon-dioxide increment is 

 less than 0.5 per cent, analytical errors play a great role not only in the 

 calculation of the respiratory quotient, but likewise to a certain extent 

 in the calculation of the total metabolism. Since the analytical errors 

 in the determination of the carbon dioxide are very much less than those 

 in determining oxygen, this may not of necessity be a serious matter. 

 On the other hand, the exact determination of oxygen necessitates the 

 skill of the best trained analyst and an especially accurate gas-analysis 

 apparatus with a carefully controlled technique. When the oxygen 



'Jaquet, Verhandl. d. Naturforsch. Gesellsch. in Basel, 1904, 15, p. 252. 

 2 Benedict, Carnegie Inst. Wash. Pub. No. 166, 1912. 



