318 



GEOWTH OF CHEMICAL CONSTITUENTS 



At 100 days of age no significant sex difference is exhibited in the per- 

 centage of magnesium and phosphorus. The percentage of calcium in 

 the ash of both bones, however, is greater in the females than in the 

 males. This sex difference is an accompaniment of the more advanced 

 state of ossification of the bones in the females as shown by their higher 

 percentage of ash. (Hammett '24 a) 



TABLE 175 



The statistical data of the gross chemical composition of the humerus and femur 

 of normal female rats at two ages 



100 days of age, 10 rats 

 Humerus 



Femur 



150 days of age, 11 rats 

 Humerus 



Femur 



At 150 days of age the identity of the humerus and femur ash in cal- 

 cium and magnesium percentage, the superiority of the femur in per- 

 centage of phosphorus, and the higher percentage of calcium in the 

 bones of the females are shown, as at 100 days of age, and are similarly 

 interpretable. 



