24 BTJLLETIN 1090, U. S. DEPARTMENT OF AGRICULTUBE. 



/906 /906 /9/0 /9I2 /9I4 /9I6 /9/3 /920 

 /OO 



>_ y , 



B 



60 



CO ^ 



20 







Fig. 4. — The average birth weight. Inbreds {A ) and controls {B), 1906 to 1920. Corrected for effect of size 



of litter as in Figure 1. 



/906 /903 1910 19/2 /9I4 /9J6 J9I6 1920 

 JOO 





60 



Co 00 

 \ 



\ 



^ 40 



20 



O 



Fig. 5.— The average birth weight of young raised to 33 days. Inbreds {A ) and controls (£), 1906 to 1920. 

 Corrected for effect of size of litter as in Figure 1. 



