158 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 



that laid down from our observations. It therefore seems clear, 

 from all observations, that the metabolism per unit of body-mass is 

 noticeably higher at 6 to 8 kg. of weight than at any other time of life. 

 Our curve indicates that the metabolism is lower from 3 to 5 kg. than 

 from 6 to 8 kg., but this is not shown by the earlier work. The gradual 

 fall from 8 to 42 kg., at which point our observations end, is also 

 apparent in all the observations. From the comparison of the calories 

 per kilogram of body-weight in all the series, the general picture is 

 thus essentially the same, and the newer data simply extend and 

 confirm the earlier observations. The striking feature of this com- 

 parison is that the new work shows a distinctly lower level all along 

 the line and brings out the lower metabolism during the first few 

 months of life. 



The scarcity of earlier material available for comparison does not 

 justify publishing here a chart for girls, but such a comparison has 

 been made. Two of the values obtained by Magnus-Levy and Falk 

 for girls weighing between 40 and 42 kg. lie but little above our curve. 

 In general, the points for girls up to 40 kg., though above our line, 

 lie fairly close to it, and are not more widely scattered than our own 

 observations. The number of points is so small, however, that they 

 give no suggestion of a general trend, but, so far as they go, they are in 

 fair conformity with our curve and indicate a higher metabolism at 

 the lower weights. 



Notwithstanding the objections raised in earlier paragraphs regard- 

 ing the probable influence of food, the evidence in all the observations 

 demonstrates that there is a profound physiological difference in the 

 metabolism of children weighing 6 to 8 kg. from that obtaining at any 

 other period of life. If correction could be made for the composition 

 of the body, it would appear that (per unit of weight of body-material 

 other than fat) the metabolism would be even greater at the early 

 weights and that undoubtedly with these weights (6 to 8 kg.) there is 

 greater metabolic intensity per unit of active protoplasmic tissue than 

 at any other point in the life of youth. 



In an earlier report 1 we emphasized the extraordinarily low heat 

 production of new-born infants, particularly on the first day of birth, 

 attributing this in part to the temperature changes and perhaps weak 

 condition of the organism after the birth and bath. It would seem 

 as though this lower metabolism is characteristic of very young 

 children and that the metabolism per unit of mass gradually increases 

 until about the age of 1 year, or a weight of 6 to 8 kg., and thereafter 

 steadily declines throughout the period of youth. 



1 Benedict and Talbot, Carnegie Inst. Wash. Pub. No. 233, 1915, pp. 103 and 118. 



