34 



HELEN DEAN KING 



TABLE 14 



Showing the average increase in the body weight ivith age for two series of albino 

 rats: (1) rats belonging to the fifteenth generation of the two inbred series {A, B); 

 {2) selected stock rats. Both series of rats ivere reared under similar environmental 

 conditions 



with age in rats belonging to the fifteenth generation of the 

 inbred series (A, B), with corresponding data for the animals in 

 the Wistar stock control series are given in table 14. 



Data for the two series of male rats, as given in table 14, are 

 presented in the form of graphs in figure 13. 



In figure 13 the graphs run close together and cross and re- 

 cross until the 150 day period. At this point the graph for the 

 inbred males mounts above that for the stock animals and sub- 

 sequently maintains this position until the end, where the stock 

 graph is the higher, since at this age the stock males were 1.3 

 per cent heavier, on the average, than the inbred males. At the 

 eight months period the space between the graphs indicates a 

 difference of 4.1 per cent in favor of the inbreds. 



The majority of the inbred rats in the fifteenth generation 

 were handicapped in their growth by being born in the summer : 



