NORMALITY OF CHILDREN STUDIED. 



41 



sent the selected classes. Since the Crum-Wood curve is derived 

 from measurements of several thousand American children, it is clear 

 that we may state with perfect propriety that, so far as this classic 

 relationship of body-weight to age is concerned, our laboratory boys 

 are normal as compared with the average American child, but are 

 inferior to the selected class of private-school boys, who are distinctly 

 heavier than other boys of the same age. In fact, at the age of 12 

 years we see that the average weight of our laboratory boys is about 

 34.5 kg., while the average weight of our private-school boys is about 

 40 kg., a very perceptibly greater weight. 



RELATIONSHIP BETWEEN HEIGHT AND AGE WITH BOYS. 



An intelligent understanding of the difference noted in the weight- 

 to-age ratios of our laboratory boys and the private-school boys can 



Yrs. 24 6 8 10 12 14 16 18 20 

 FIG. 4. Relationship between height and age with boys. 



not be had until we have some conception of the relative heights of 

 these boys. Are these private-school boys heavier because they are 

 taller, or is the weight independent of height? To answer this question 

 we will consider next the relationship of height to age for boys, as 

 pictured in figure 4, where we have exactly the same sets of observa- 



