SOME CURRENT THEORIES 



45 1 



Per cent 

 Soo 



400 



Evidently there must be no conflict between the conclusions 

 which we may draw from the two kinds of increments or the two 

 kinds of curves, since both are obtained from the same statistics. 



In the one case growth 

 resembles an autocata- 

 lytic reaction, in which 

 the amount of substance 

 added in a given time 

 increases up to a certain 

 point and then de- 

 creases, while in the 

 other we observe that 

 the rate of growth, or, 

 . in other words, the 

 growth activity per unit 

 of weight, decreases 

 from a very early period 

 on. A. W. Meyer ('14) 

 has criticized Ostwald 

 and Robertson for using 



300 



' 1 1 1 1 I (— — — f h 



Months I 23456789 



Fig. 200. — Curve of human growth for the embryonic period and the month of 

 birth, drawn from the percentage increments of weight in Table XIII: each vertical 

 interval indicated on the axis of ordinates represents an increment of 100 per cent in 

 weight, and each horizontal interval on the axis of abscissae, one month. 



absolute instead of percentage increments of growth as the basis 

 of their curves. This criticism is somewhat beside the point, for it 

 must be remembered that the absolute and relative increments 

 represent simply different aspects of the same process. 



