48 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 



growth factors from our graphs and the sketched curves accompanying 

 them. Almost immediately the fact is forced upon one that the re- 

 lationships between height, weight, and age are by no means to be 

 considered as primarily due to the age factor, but the general con- 

 figuration of the body will indicate whether the child is too heavy or 

 too light for his height. The relationships of height to weight are of 

 most importance. This statement is not to be interpreted as meaning 

 that the height-to-age ratio and the weight-to-age ratio should be 

 ignored. Still, the erroneous ideas to which the consideration of the 

 ratios of weight or height to age alone may lead one are well brought 

 out in the discussion of our charts. Here it was shown that although 

 the curves for the private-school children indicated apparently a great 

 superiority over our laboratory children, a subsequent analysis of the 

 relationship between height and weight alone proved that the superi- 

 ority is by no means as great as would at first be implied, and, at 

 least so far as the relation of height to weight is concerned, the private- 

 school children are not superior to those of our laboratory series. 



The anomalous situation raised by an inspection of these charts leads 

 at once to a consideration of the question of growth, for it is during the 

 period from birth to puberty that we have the greatest changes in 

 growth, both in height and in weight. Indeed, it has been stated 

 that a young infant goes through physical changes in two or three 

 months which it would take adults several years to equal. From the 

 slopes of practically all of our curves it is very clear that the rate of 

 growth is greatest during the first year of life and gradually diminishes 

 as the child grows older. A study of a large number of measurements 

 shows that the greatest gain in weight is made during the first 5 or 6 

 months of life, when a normal infant almost doubles its birth-weight. 

 During the second 6 months of life an infant gains approximately the 

 same amount of weight as during the first 5 or 6 months; but whereas 

 the increase in weight during the first 5 or 6 months is 100 per cent, 

 in the second 6 months of life it is only about 50 per cent. During 

 the second year of life the increase in weight diminishes to approx- 

 imately 25 per cent, and in the third year it is less than 20 per cent, 

 The percentage increase in height becomes less and less with increasing 

 age, somewhat similar to that noted for weight. Thus, the increase 

 is about 21 per cent during the first 6 months of life, 14 per cent during 

 the second 6 months, and correspondingly less as the child grows older. 

 With these general principles of growth our curves conform in general, 

 particularly the curve illustrating the weight-to-age ratio. 



It must be clearly recognized at the outset that growth should not 

 be interpreted as meaning only addition of flesh. Growth means the 

 skeletal growth as well, and it is only by establishing the proportion 

 between the skeletal growth and the addition of flesh that the most 

 intelligent consideration of growth can be made. Among the numer- 



