METABOLISM AS AFFECTED BY GROWTH. 



147 



While a reasonably clear trend for the metabolism is shown in the 

 charts plotted on the basis of total calories, it is only with great diffi- 

 culty that one may discern a general trend in figure 30, which is at 

 best only a conjecture. Still, the usual method was followed for 

 sketching this composite curve. The line obtained is much more 

 irregular than any of the curves thus far considered. 



Cals. 



CALORIES PER KILO. REFERRED TO AGE. 



BOYS. 



FIG. 30. Basal heat production of boys per kilogram of body-weight per 24 hours 



referred to age. 

 Point inclosed in square signifies puberty established. 



The values for the earlier months of life, as shown in the chart in 

 figure 30, indicate a clear tendency for a lower metabolism per kilo- 

 gram of body-weight than at the end of the first year, thus justifying 

 the upward trend of the curve. Subsequent to 5 years, the values 

 are definitely lower than those in the first 3 years of life. Although 

 there is great irregularity in the dispersion of the points, it was 

 thought best to represent the trend after 6 years by a straight line, 

 for the irregularity noted in the distribution of the points is perhaps 

 no greater than that found with adults. A most careful analysis 

 of the material for adults indicated that the straight-line equation 

 gave as close a representation of the changes in metabolism per kilo- 

 gram of body-weight with changing years as could be expressed by a 

 curve of a higher order. Still, the laying on of this curve must be 

 looked upon only as an empirical representation of a general trend and 

 not as a mathematically established average. 



Of special significance in this chart, therefore, is first the extra- 

 ordinary dispersion of the points about the smoothed curve. What- 

 ever degree of regularity has been heretofore assumed by physiologists 



