SEX AND SOCIETY 205 



extremity a still shorter lower extremity 

 and so on. In short, the woman is a less 

 muscular, less motor type. 



The differences in the relative length of 

 the limb-bones, and in the size and curves 

 of the component parts of the pelvis, are 

 observable at birth, but they may be obscured 

 for a time by the different growth periods 

 in the boy and girl. Thus the girl's period 

 of most rapid increase in height falls usually in 

 the twelfth and thirteenth year, while the boy's 

 does not begin till the fourteenth and fifteenth 

 year, and the period of increase in weight 

 begins correspondingly earlier in the girl. 



Much has been written about the difference 

 in cranial capacity, but there is no certainty 

 as to what that implies. Accurate measure- 

 ments of the skull have been taken many times, 

 and they show, according to Ranke and others, 

 that the circumference of the skull is absolutely 

 greater in the male, but relatively greater 

 in the female. As to brain development, 

 out of all the statements by later investigators 

 the only half-certainty that emerges is that 

 the central region, the seat of the voluntary 

 movements, is rather more highly developed 

 in the male. 



Physiologists have of late years devoted 

 much attention to the investigation of the 

 glands of internal secretion, but it is too soon 

 to generalise as to sex-differences. Bucura 

 lays stress on the fact that the thyroid gland 

 is not only relatively larger in woman but 

 " plays an enormously greater role in her 

 life." The same is true to some extent of 



