POSTNATAL GROWTH IN THE ALBINO RAT 



15 



We may therefore conclude that for the human (British and 

 American) the coefficient of variation for the body weight in the 

 newborn male is about 15.7. At six years, it has diminished to 

 a little below 11, and fluctuates in this neighborhood until the 

 twelfth year. During the acceleration of growth from thirteen 

 to sixteen years, the coefficient of variation increases to 16 or 

 17, thereafter diminishing rapidly to about 11 in the young adult. 

 For the female newborn the coefficient of variation (14.2) is 

 somewhat below that of the male. From six years onward, the 

 coefficient of variation appears to be correlated with the relative 

 rapidity of body growth, being somewhat greater in the female 

 up to the age of fourteen, after which the male exceeds it. 



In comparison with the human species, the coefficient of vari- 

 ation in the body weight of the rat at birth appears somewhat 

 smaller. Although in all subsequent stages (except at the age of 

 puberty) the variation in the human body is smaller than at 

 birth, in the rat it appears constantly greater, and shows no 

 evident correlation with the rate of growth of the body. 



TABLE D 

 Body weight of St. Louis school children {from Porter's data) 



