EARLIER RESEARCHES WITH NEW-BORN INFANTS. 33 



deficit is less than 0.7 per cent, analytical errors of plus or minus 0.03 

 per cent (which are not at all infrequent) will have a very considerable 

 influence upon the computations of the respiratory quotient. 



The air analyses published by most users of the Jaquet apparatus 

 have shown discrepancies in the oxygen content of external air which 

 lead one to suspect analytical errors. We note with interest, however, 

 Hasselbalch's statement regarding his own experience in analytical 

 analysis, which indicates that he found very insignificant variations 

 in the composition of the atmosphere. Thus we may properly infer 

 an especially careful analytical procedure. But of more significance 

 is the fact that Hasselbalch's published results show us that his carbon- 

 dioxide increment was frequently 1 per cent or even 1.5 per cent. It 

 is clear that Hasselbalch's analytical data are probably as accurate 

 as any determinations thus far made of the carbon-dioxide increment 

 and the oxygen deficit in an open-circuit respiration apparatus, and we 

 may have an unusual degree of confidence in his values. 



The number of infants studied by Hasselbalch was too few to obtain 

 definite physiological constants, and although he reports 31 experi- 

 mental periods on 20 infants, and as a result of his accurate technique 

 was able to make deductions from them, it is obvious that a problem 

 so important as the metabolism during the first week of life demands 

 not simply confirmation but further elaboration of data. We shall 

 have occasion, in discussing our own results subsequently, to refer to 

 the sharply drawn conclusions reported by Hasselbalch. 



OBSERVATIONS BY WEISS. 



In 1908 G. Weiss, 1 employing a type of respiration apparatus which 

 was entirely different from those previously used for studying infant 

 metabolism, made a most interesting series of observations on new-born 

 infants, in which both the carbon-dioxide output and oxygen intake 

 were studied. Twelve new-born infants were observed, ranging in 

 age from 1 to 11 days. His apparatus consisted of a metal chamber 

 supplied with a window and a thermometer, and having a capacity of 

 60 liters. The infant was hermetically sealed in this chamber and 

 remained there for approximately an hour. The air in the chamber was 

 then thoroughly mixed by an electric fan and a sample taken for analy- 

 sis. This method of studying the gaseous exchange was employed 

 by Chauveau and Kaufmann and used with especial success by Laulanie. 

 The carbon-dioxide increment in the chamber and the oxygen deficit 

 could be readily computed from the results of the analysis and data 

 obtained as to the total oxygen absorption and carbon-dioxide produc- 

 tion of the infant. 



The author points out that with new-born infants the carbon-dioxide 

 excretion is two, three, or sometimes four times greater per kilogram of 

 body-weight than it is with the adult. He found, for example, that the 

 carbon dioxide excreted varied from 1,064 c.c. to 337 c.c. per kilogram 



1 G. Weiss, Bui. de 1'Acad. M6d., 1908, 60, 3d ser., p. 458. 



