100 PHYSIOLOGY OF THE NEW-BORN INFANT. 



shown that one of the greatest factors influencing thermogenesis, i. e., 

 the active mass of protoplasmic tissue, probably develops according 

 to the general fundamental law of growth as expressed by the cube 

 root of the square of the body-weight. We feel wholly justified, there- 

 fore, in attempting to study the heat-production of these infants on 

 the empirical basis of the heat-output per square meter of body-surface 

 per 24 hours. 



The actual measurement of the body-surface of these infants was 

 impossible, as the methods used by Meeh and Lissauer were precluded 

 and no other method giving accurate results was available. At the 

 moment of writing a method which promises well, namely, the Du 

 Bois formula, makes it not at all impossible that body-measurements 

 may be practicable in future investigation of this type. As the data 

 regarding the body-surface of these infants could not be obtained by 

 means of actual measurement, we employed in our calculations the for- 

 mula of Lissauer, in which the constant 10.3 is multiplied by the cube 

 root of the square of the body-weight. 



The results thus obtained show that the average minimum heat- 

 production per square meter of body-surface for the 94 infants was 612 

 calories per square meter per 24 hours. The largest minimum value 

 was 732 calories with infant No. 81 and the smallest 459 calories with 

 infant No. 104. Even on this basis, which is supposed to equalize not 

 only all animals of similar species but also animals of different species, 

 we do not find comparable values for these infants throughout the 

 whole series. 



For a better visualization of the values for the heat-output com- 

 puted on this basis and given in table 12, the minimum heat-production 

 per square meter of body-surface per 24 hours has been plotted against 

 the body-weight. (See fig. 6.) Here also we find very wide deviations 

 from the average value of 612 calories. Using again, for the purpose of 

 discussion, the hypothetical limits of =*= 10 per cent, i. e., 675 calories and 

 550 calories, respectively, we find that there are 18 values which are 

 more than 10 per cent below the average value and 13 over 10 per 

 cent above the average value. Thus in practically one-third of our 

 observations the results obtained vary more than 10 per cent from 

 the average value. 



In considering the results obtained with our infants and graphically 

 shown in figure 6, it is of particular interest to refer to the previous 

 conception regarding the heat-production per square meter of body- 

 surface of infants. Although infants have rarely been studied in the 

 first week of post-natal life, the prevailing opinion of physiologists has 

 been that very small and very young animals have proportionally a 

 much larger heat-production than has the adult organism. From the 

 review of the earlier literature given in our first report 1 it will be seen 



Benedict and Talbot, Carnegie Inst. Wash. Pub. No. 201, 1914, p. 11; also, Am. Journ. 

 Diseases of Children, 1914, 8, p. 3 and 43. 



