24 BULLETIN 1090, U. S. DEPARTMENT OF AGRICULTURE. 



J906 /908 /9I0 /9I2 /9I4 /9I6 /9/S /920 

 /OO 



X\ xr y — 



c5<? 



* 40 



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 1903 1910 19/2 J9I4 1916 J9I8 1920 

 /OO 



80 



{/) 60 



X 



I 



^40 



20 



> -<;<l >^ - - 



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

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



