CHAPTER VI. 
SEXUAL DIFFERENCES IN GROWTH. 
When the curves of growth in weight, height standing, 
height sitting, span of arms and girth of chest are drawn on 
the same system of co-ordinates, as has been done in Plates 
XXV to XXIX inclusive, the attention of the observer is 
arrested by the extraordinary difference in the development 
of girls and boys during the period of prepubertal 
acceleration. Girls enter this time of rapid growth at age 11 
or 12, two years earlier than boys, and during several years are 
larger than boys of the same age. The period during which 
girls are larger than boys does not correspond exactly with 
the period of accelerated development, but begins and ends 
a little later. The ages at which girls begin and cease to be 
larger than boys are given in the following table. The ages 
TABLE No. 29. 
AGES AT WHICH GIRLS BEGIN AND CEASE TO BE LARGER THAN Boys. 
Age at which Girls begin 
to be larger than Boys. 
Age at which Girls cease 
to be larger than Boys. 
Percentile Grades. 
Percentile Grades. 
DIMENSION, 
25 50 75 25 50 75 
Weeightissius. cis yes 12,8. yrg.|12,2- yrs.'11-% yrs.|16-3 yrs.|1 rs.| 14-8 rs. 
Height standing..... Ape | ee time ee lige ee lia ri 
Height sitting... .. aieeeenr ine clr lieth ce lew 16 “ 
Span of arms......... 123% J1id © 1118 6 1153 oe lide ee ee 
Birth of chest: cs ..<; 128; « [12 « fie” «© lies 15 iB 
Height of face from 
hair line to point of 
chin...... 114% yrs. 1 ** 
are nearly the same for the same percentile grade in all five 
dimensions. 
(3 
An examination of plates XXX to XXXVI 
