GROWTH. 57 



With regard to the measurement of body-surface, we must assume 

 that the Du Bois linear formula gives the actual areas very closely. 

 A note of caution has been sounded, however, by Du Bois, 1 who 

 specifically states that it does not seem advisable to use this formula 

 for infants under 2 years of age until the factors have been tested 

 by the measurements of other infants. In working out their formula, 

 the Du Boises used a small cadaver of a child 21 months old, weighing 

 6.27 kg., with a height of 73.2 cm., measured about two hours after 

 death. They state " the subject was small for her age and had suffered 

 from rachitis; the epiphyses at the wrists were large and the thorax was 

 pigeon-breasted, being narrow and very deep antero-posteriorly." 2 

 The error in measurement by the linear formula as compared with the 

 measurement of the cast was 2.9 per cent. We are of the opinion 

 that, in limiting the use of their formula, weight rather than age should 

 be the criterion, and that hi the case of children the limit should be 

 not children under 2 years of age but children under 6.27 kg. in weight. 

 With this modification of their limit we are in full accord with the 

 Du Boises. 



It seemed to us, however, that if we computed the surface areas of 

 our children, both by the Du Bois linear formula and by some standard 

 formula, such as the Lissauer formula, 3 we could compare the values 

 obtained on these two bases for children below 6.27 kg. in weight, note 

 the agreement between the two methods, and thus estimate approx- 

 imately the probability of accuracy in the linear formula for weights 

 below 6 kg. Exactly this procedure we have carried out. We have 

 carefully measured by the Du Bois linear formula the surface areas of 

 14 boys and 19 girls of weights under 6.27 kg. Comparing the areas 

 thus measured with the areas computed by the formula proposed by 



3 i" 



Lissauer (10.3 ^w 2 ), we found that with our boys there was a tendency 

 for the area by the Lissauer formula to be slightly higher than that by 

 the Du Bois linear formula; therefore, in estimating the body-surfaces 

 of boys with weights of 6 kg. or less, we propose employing the formula 

 #%2, substituting the factor 10.0 for 10.3, in the belief that 10.0 

 is a more representative factor than the 10.3 used by Lissauer. This 

 new factor of 10.0 gives results about 3 per cent lower than the Lissauer 

 factor. Similarly, for estimating the body-surfaces of girls below 6 kg. 

 in weight, the factor would be more nearly 10.1 on the average, rather 

 than 10.3, that is, 1 per cent larger than the factor for boys. Accord- 

 ingly, for computing surface areas of children with body-weights of 

 10 kg. or less, the factor would be not far from that proposed by 

 Lissauer. This agreement between the new factors suggested by 

 us (which were obtained by inspection of the surfaces computed by 



1 Sawyer, Stone, and Du Bois, Arch. Intern. Med., 1916, 17, p. 855. 



2 Sawyer, Stone, and Du Bois, loc. cit., p. 856. 



3 Lissauer, Jahrb. f. Kinderheilk., 1902, N. F., 58, p. 392. 



