62 THE GROWTH OF THE BRAIN. 



This may be a result of age alone or may be complicated 

 by the fact that previous pregnancies tend to increase 

 the weight of the last born child. To these conditions 

 are also to be added the length of gestation and individual 

 differences in the growing power of the fcetus, on both of 

 which the foregoing conditions must exert an influence. 



A record for growth during the first year of life is 

 given from Vierordt after Meeh. 1 This shows the rapid 

 increase in weight, which, with the exception of an 

 insignificant regression during the twenty-first week, is 

 continuous. (Fig. 12.) 



The rate of growth has already been mentioned, and 

 it will be important to determine for man the rate of the 

 increase in weight. The facts at first sight do not 

 arrest the attention, but when we stop to consider, it is 

 plain that there must be both variations, and also a 

 great diminution in the rate, similar to that pointed 

 out by Minot in his study of guinea-pigs. If the weight 

 of the body at any date be taken as a basis, the per- 

 centage increase on this figure during the next unit of time 

 can be calculated, and so on for any number of succes- 

 sive intervals. Treating in this manner the figures for 

 the increase in weight, as given by Roberts, they yield 

 a curve as shown in Fig. 13, where from birth to the 

 first year there has been an increase in weight of 240 

 per cent, for the males, and 190 per cent, in the females. 

 But this rate diminishes during the succeeding years 

 with astonishing rapidity. 



This curve indicates that the weight increase which 

 we measure between birth and maturity may be re- 

 garded as the latter end of a dwindling capability, in 

 which there is a slight revival at the age of puberty, 

 a revival representing the last strong impulse in the 

 direction of enlargement. 



1 K. Vierordt, Anatomic und Physiologic des Kindesalters, 1881. 



