REPROD UCTION. 



925 



The length and the weight at birth vary very greatly. The average measure- 

 ments, as given for over 450 infants in Great Britain, are, for height, males 

 19.5 inches, females 19.3 inches; for weight, males 7.1 pounds, females, 6.9 

 pounds. The weight at birth is said to be greater the nearer the mother's 

 age is to thirty-five years, the greater the weight of the mother, the greater 

 the number of previous pregnancies, and the earlier the appearance of the first 

 menstruation. Race and climate are also of influence. Minot l believes that all 

 of these influences work principally through prolonging or abbreviating the 

 period of gestation, and that the variations at birth depend partly upon the 

 duration of gestation and partly upon individual differences of the rate of 

 growth in the uterus. 



Growth of the Body after Birth. In studying the growth of the body 

 after birth two methods have been employed, named the " generalizing " and 



Age. 5 10 15 20 Years. 25 



20 



10 



140 



120 



100 



80 



40 



20 



Males. 



Females. 



FIG. 316. Diagram showing increase of stature and weight of both sexes, as determined by the Anthropo- 

 metric Committee of the British Association.' 



the " individualizing " methods. The former consists in deducing the course 

 of growth by averages or other central values from statistics taken from a 

 large number of individuals at different ages. It is the method more com- 

 monly employed ; it shows the course of growth of the typical child, but is 

 inexact in enabling future growth to be predicted in individual cases. The 

 individualizing method consists in measuring the actual growth of the same 

 individual through successive years ; it shows well the relation of the indi- 



1 C. S. Minot : Human Embryology, 1892. 



2 Roberts : Manual of Anthropometry, 1878. 



