DISCUSSION OF RESULTS. 147 



plete muscular repose, was slightly greater than immediately after 

 feeding. But the general picture derived from these observations indi- 

 cates that the ingestion of milk played a very slight role, if any, in 

 affecting the heat-production of the infants studied. 



Recent observations in this laboratory during a 31-day fast showed 

 that, as soon as food was completely withheld, the body storage of 

 glycogen was rapidly drawn upon and a distinct acidosis appeared when 

 it was exhausted. Our experience with diabetics and with normal 

 individuals subsisting upon a carbohydrate-free diet 1 gives evidence 

 that such an acidosis tends to increase the basal metabolism. Addi- 

 tional light has been thrown upon this subject by Schlossmann and 

 Murschhauser 2 who have shown in a recent publication the influence 

 of the withdrawal of food upon the excretion by infants of products 

 of acidosis, particularly acetone, diacetic acid, and £-oxy butyric acid. 

 Even in the first 24 hours of fasting, definite evidence of the excretion 

 of /3-oxybutyric acid shows the beginning acidosis. Knowing, as we 

 do, that acidosis strongly tends to increase the metabolism, one sees 

 instantly that a point or a moment when the influence of the previously 

 ingested food ceases and the influence of an oncoming, though slight, 

 acidosis begins, is extremely difficult to foretell, with our present 

 knowledge. It should not be overlooked, however, that Schlossmann 

 and Murschhauser did not find an increased heat-production in these 

 infants showing incipient acidosis although we are inclined to doubt 

 the validity of drawing conclusions regarding so subtle a factor as aci- 

 dosis from periods with such changes in the degree of repose. 



While, therefore, we recognize clearly that the presence of food in 

 the alimentary tract of our infants has distinct theoretical objections, 

 we believe that such influence, if it exist, can play no quantitative role 

 in the striking comparisons of the basal metabolism of different infants 

 which are made in the subsequent pages. 



NORMALITY OF INFANTS STUDIED. 



In carrying out this study of infant metabolism, we found ourselves 

 immediately confronted by the difficulty of determining what is the 

 normal infant. An inspection of the data supplied by Holt, 3 Heubner, 4 

 Camerer, 5 Gundobin, 6 and Sutils 7 shows noticeable variations in the nor- 

 mal weight of infants of different nationalities — variations that may easily 

 amount in the earlier months to 5 or 8 per cent, even for a carefully 

 selected, healthy, breast-fed infant. Our infants were usually bottle- 

 fed and for the most part were under the normal weight. To show as 



Benedict and Joslin, Carnegie Inst. Wash. Pub. No. 176, 1912, p. 134. 



Schlossmann and Murschhauser, Bioc'iem. Ztschr., 1913, 56, p. 396. 



3 Holt, Diseases of infancy and childhood. New York and London, 6th ed., 1911. 



4 Heubner, Lehrbuch Kinderheilkunde, 3d ed., Leipsic, 1911, 1, p. 7. 



5 Camerer, Der Stoffwechsels des Kindes, Tubingen, 1896. 



6 Gundobin, Die Besonderheiten des Kindesalters, Berlin, 1912. 



7 Sutils, Guide pratique du pesage pendant les deux premieres annees, Paris, 1889. 



