GROWTH OF THE SKELETON 251 



GROWTH OF SKELETON IN WEIGHT ON AGE 



Although the determination of the skeleton weight according 

 to age was not specially considered in this study, yet the series 

 yields data which can be used to show this relation. If we con- 

 sider the body weights as they appear in table 1 to be normal for 

 age, the data in table 74 (Donaldson, '15) being taken as the 

 standard, then between birth and 365 days the first twenty-seven 

 groups can be used for the males and the first twenty-two groups 

 for the females. The data are presented in table 5. When these 

 data for the weight of the fresh skeleton are plotted for each sex 

 on the base line for age, there appear the smooth graphs shown 

 in chart 6. 



It is the form of these graphs which is of value, for they show 

 that in both the male and the female the graph for the weight 

 of the fresh skeleton is sinuous and very similar to the graph for 

 the weight of the entire body on age (Donaldson, '06) despite the 

 fact already noted that after the first few days of life the relative 

 weight of the skeleton is continually diminishing. 



While the form of the graph is trustworthy the absolute 

 values for the weight of the skeleton at the given ages are peculiar 

 to these data and not general, and therefore should be used for 

 comparison only with caution. The smaller absolute weight of 

 the skeleton in the female goes, as the tables show, with the 

 smaller body weight at the several ages. 



Tables 1 to 5 and charts 1 to 6 show in a general way the 

 growth in the weight of the skeleton and its larger parts on 

 body weight and age. We pass now to some of the smaller 

 divisions of the skeleton. 



ON THE GROWTH OF THE PARTS OF THE LIMBS 



Our records permit us to determine the manner in which each 

 of the three divisions of the limbs increases in weight. Table 6 

 shows the weight of all the bones in both fore limbs and also the 

 percentage values for the humerus (2), ulna plus radius (2), and 

 carpus plus fore foot (2) at intervals of 0.02 gram, while table 7 



