52 



SIZE INHERITANCE IN RABBITS. 



the growth of the body as a whole. What makes the difference between 

 a big rabbit and a small one is clearly a quantitative difference in these 

 general factors, or it is something which modifies the action of these 

 general factors, which amounts to the same thing. That which deter- 

 mines the adult size of a rabbit determines (if other conditions remain 

 constant) both the rate at which it grows and the time when growth 

 ceases. A large race of rabbits has a steeper growth curve than a 

 small race and the period of growth continues longer (see Castle et aL, 

 1909) . The proportions of the body also change in a constant direction 

 as growth proceeds. For example, the larger a rabbit becomes the more 

 elongated its skull becomes. Is a larger size attained in one race simply 

 because growth continues longer, or is the character of growth different 

 from the beginning? A study of immature rabbits of large and small 

 races at corresponding absolute size stages might throw light on this 

 question. 



TABLE 9. Correlation between the measurements 0. M. and Zp. in the rabbits studied. 



r = 0.750. 



TABLE 10. Correlation between the measurements 0. M. and H. r = Q.71fi. 



