THE NORMAL CHILD 



563 



Lung Capacity Curves. Girls. 



One of the most useful and practical indices of growth is the weight- 

 height coefficient, which expresses the comparative solidity or robustness 

 of the individual, and therefore, other things being equal, his general 

 nutrition. 



The lowest ratio in this group of boys is .15 at six years, and the 

 highest .40 at 17^ years of age. There is little or no apparent difference, 

 as a rule, between the tall boys and the short boys, except that the ac- 

 celeration begins earlier for tall individuals. For example, if we take 

 0.23 as representing a given physiological stage of development, it will 

 be noted that the time shifts chronologically in a fairly uniform man- 

 ner between 7 and 8 years of age with No. 1, to 14^ years for No. 14. 



It will be noted in the boys' lung capacity curves that No. 9 in the 

 first chart, who is relatively heavier than the others for his height, also 

 has more lung capacity. This is significant since the other boys hold 

 approximately their relative places for height, weight and lung ca- 

 pacity. 



The boys have greater lung capacity than the girls, on an average, 

 for all periods except at about 13 and 13^ years of age. The develop- 



