638 JOHN E. MUKLIN 



stantial agreement. For an infant who cries no more than the average nor- 

 mal infant probably 30 per cent increase above the basal would more than 

 cover the energy requirement for maintenance ; while for an infant who 

 cries "most of the time" (admitting considerable latitude in the use of 

 the expression), probably 40 per cent above the basal would be more than 

 adequate ; for it is certain that, no newborn infant can continue to cry at a 

 rate sufficient to increase the metabolism 40 per cent for more than a 

 few hours out of the twenty-four. 



6. Influence of Food and External Temperature. Very few observa- 

 tions have been made indicating that the food of the newborn has any 

 dynamic effect. Hasselbalch (a) reports two observations on premature in- 

 fants in which he surmises that the increase of some 15 per cent in 

 metabolism the second period is due to the "work of digestion." "At 

 any rate," he asserts, "it was impossible to recognize a difference in the 

 muscular activity of the infant." Since the first effect of hunger is to 

 induce muscular activity in the form of crying, it is very difficult to secure 

 .complete muscular repose on empty stomach so as to have a basis of com- 

 parison with periods following the ingestion of food. In Hasselbalch's 

 comparison just cited both periods follow the feeding and the more 

 active work of digestion in the second period is inferred from the 

 higher respiratory quotient. Coupled with the difficulty just mentioned 

 is the natural reluctance of the physician to give the newborn a large 

 feeding. In fact, it is quite possible that the stomach of the child at 

 this time cannot contain enough food at a single filling to raise the metab* 

 olism sensibly. 



We are equally without convincing evidence that external temperature 

 acting independently can influence metabolism in the newborn. Scherer 

 reported a difference of 23 per cent in oxygen absorption by the infant 

 between what he called summer temperature (16 to 26.8 C.) and winter 

 temperature (9.5 to 16.2 C.). But there was no control of muscular ac- 

 tivity, or even notes regarding crying. Hasselbalch conducted his ex- 

 periments at an average temperature of about 33 C. ; Bailey and Murlin 

 maintained a temperature of 27 to 29 C. ; while Benedict and.Talbot 

 kept their chamber air at approximately 20 C. Hasselbalch is deeply im- 

 pressed with the fact that his newborn infants (most of them only a few 

 hours from birth) produced only 270 c.c. of carbon dioxid per kilogram and 

 hour and that "this is not essentially higher than the corresponding figure 

 for a grown individual in absolute repose." From the connection in which 

 the author alludes to this comparison one might infer that the low metab- 

 olism which he mentions was due to the absence of all "chemical regula- 

 tion" since the temperature was "so regulated that the question of the 

 feeble heat regulation of the infant is eliminated as far as possible." Re- 

 sults even lower than this, however, may be seen in several instances 

 amongst the data reported in the more recent publications, notwithstand- 



