108 PHYSIOLOGY OF THE NEW-BORN INFANT. 



ably question values varying 10 per cent, a uniformity in values with 

 variations of only =*= 6 per cent, with but a few striking exceptions, is at 

 least worthy of serious consideration. 



From these observations we have derived a formula, cal. = ZX12.65, 

 which takes into consideration both the length and the body-surface 

 and believe that it is possible to compute the minimum heat-production 

 of infants per 24 hours and per square meter of body-surface by multi- 

 plying the length I by the constant 12.65, this constant representing 

 the average calories per square meter per 24 hours per centimeter of 

 length as found from actual observations made with this group of 

 infants from 1^ to 6 days old, inclusive. Thus our formula becomes: 



Total cal.^ZX^.eSXlO.S^wt 2 



The heat-production for the 48 infants shown in figure 10 has been 

 computed by means of this formula and the results are compared in 

 table 14 with the heat-production as determined by indirect calorimetry 

 from the gaseous metabolism. The plus or minus differences between 

 the two values are, for the most part, well inside of 6 per cent, the 

 widest variations being in the case of infants Nos. 53 and 54, with 

 differences of 11.9 per cent and +12.4 per cent, respectively. Aside 

 from infant No. 75, with a variation of 10.6 per cent, practically no 

 other values are found which vary over 7 per cent from the value 

 determined by indirect calorimetry. We believe, therefore, that we 

 are justified in presenting this formula as a reasonably accurate means 

 of computing the minimum heat-production of infants from H to 6 

 days old. 



It is of course not unlikely that, with the progress of the interesting 

 researches of Du Bois on the measurement of body-surface, the Lissauer 

 constant may have to be discarded. As the body-surface is simply 

 an empirical index of the law of growth, we would strongly emphasize 

 our belief in the advisability of securing the most exact measurements; 

 at the same time we would further express our disapproval of any con- 

 ception of a causal relationship between body-surface and heat-produc- 

 tion. As an aid to pediatricians, however, we have computed various 

 data which may be used for obtaining the minimum metabolism of 

 new-born infants. In table 15 the body-surface is given for weights 

 ranging from 2 to 5 kg., as computed with the Lissauer formula. Since, 

 as brought out in the previous discussion, the heat-production per 

 square meter of body-surface becomes a function of length times a 

 constant, we have also computed the theoretical heat-production per 

 square meter per 24 hours for infants varying in length from 45 to 55 

 cm., using the constant of 12.65 found in our observations. These 

 values are given in table 16. Consequently, to find the total minimum 

 heat-production per 24 hours for any infant, which is of especial value 

 to the pediatrician as indicating a basal value, one has but to multiply 



