12 



PHYSIOLOGY OF THE NEW-BORN INFANT. 



EARLIER RESEARCHES WITH NEW-BORN INFANTS. 



Considering the marked physiological loss in weight during the 

 first week of life, the rapidly changing character of the nourishment, and 

 the supposed imperfect heat regulation of the new-born infant, together 

 with the fact that all human beings must pass through the experiences 

 of this period, it is surprising that so little evidence regarding both the 

 character and the amount of human metabolism during the first week of 

 life is available. There are almost no reliable observations on the 

 character of the katabolism and the majority of observations on the 

 amount of metabolism are, in the light of present-day technique, 

 seriously vitiated by the fact that, at the time the researches were 

 made, the importance of complete muscular repose on the part of the 

 infants was but imperfectly realized. 



OBSERVATIONS BY MENSI. 



Although Forster, 1 in 1877 studied the carbon-dioxide output of an 

 infant 14 and 60 days after birth, and 10 years later Langlois 2 studied 

 the heat-production of an infant 15 days old, it was not until the research 

 of Mensi 3 in 1894 that we find any observations on the gaseous metab- 

 olism or heat-production of infants during the first week of life. 



As a matter of fact, Mensi's infants were all somewhat under the 

 normal weight of a new-born infant, and while the oxygen consumed per 

 kilogram per minute, as reported by Mensi, appears to be reasonably 

 uniform, the extraordinarily low respiratory quotients noted by him 

 still leave the experimental procedure somewhat in doubt. The appa- 

 ratus used by Mensi has, so far as we know, never been described. 

 After a number of efforts we have finally been able, through the kind- 

 ness of Professor G. Fano of Florence and Professor Herlitzka of Turin, 



Forster, Amtlicher Bericht der 50. Versammlung deutsch. Naturforscher u. Aerzte in Miinchen, 

 Munich, 1877, p. 355. Supplementary data regarding these two observations were given in a per- 

 sonal communication to Professor Magnus-Levy and published by him in the Archiv f. Anat. u. 

 PhysioL, 1889, Suppbnd., p. 314. According to Professor Forster, the data were obtained on a 

 girl, " bei ziemlicher Ruhe." Although the infant was older than those included in our own study, 

 we consider the material of sufficient importance to give the following tabular data, which were 

 published by Magnus-Levy regarding Forster's observations: 



2 Langlois, Journ. de 1'Anat. et de PhysioL, 1887, 23, p. 400. Langlois' observation on an infant 

 15 days old was only incidental and, in view of the known errors of the calorimeter employed, the 

 values can have only an historic interest. 



3 Mensi, Giorn. d. R. Accad. di Med. di Torino, 1894, 57, p. 301. An abstract of Mensi's obser- 

 vations was given in our earlier publication. See Benedict and Talbot, Carnegie Inst. Wash. 

 Pub. No. 201, 1914, p. 14. 



