INCREASE IX THE WEIGHT OF THE ENTIRE BODY. 55 



males and females there are, then, two principal periods 

 of acceleration in weight increase. The first is observed 

 in both sexes in the years immediately following birth, 

 and is most marked during the first year. At the tenth 

 year weight increase in the female is accelerated for the 

 second time, and later the curve for the female crosses 

 that for the male. As indicated on these curves this 

 acceleration lasts for about four years. The accelera- 

 tion in the male does not begin until a year or two 

 later, but is greater than in the female, and lasts for a 

 longer time. It therefore appears that the female 

 exhibits the second acceleration somewhat earlier in 

 life, and for a shorter time ; and by reason of this there 

 occurs the curious convergence of the two curves, a 

 feature which all careful statistics on the growth of 

 children show. 



The relations just described are illustrated in another 

 way by the curves of Stephenson given in Fig. IQ, 1 curves 

 which are based on the observations by Bowditch as well 

 as those by Roberts. They show the annual absolute 

 increase in weight for the two sexes. 



Returning to the statistics by Roberts, it becomes 

 evident that the information to be derived from them 

 fails somewhat in explicitness because they have been 

 formed by weighing and measuring many children at 

 different ages, and not following the growth of in- 

 dividuals through the entire period of years. While 

 in a large way the " general " and " individual " methods, 

 as they have been called respectively, give similar results, 

 yet there are some details in which they necessarily 

 differ. Different children do not undergo the pre-pubertai 

 acceleration in growth between the same ages, and while 

 in the case of boys, as shown by the general method, 

 it may begin even before the eleventh year, and 

 1 Stephenson, Lancet, 1888. 



