EFFECTS OF INBREEDING AND CROSSBREEDING. 



1906 /90S mO /9I2 /9/4 /9/6 /9/S 



<i 2 



1 o 



' ^t- i^_ r £ iv_ 



27 

 1920 



B 



1906 

 5 



Fig. 8.— The average size of litter. Inbreds (^4 ) and controls (B ), 1906 to 1920. 



1906 1910 /9/2 /9/4 /9I6 /9/6 



1920 



B 



Ja 4 

 fc! 



% 



^ — 7- 



Fig. 9.— The average number of litters produced per year by mature matings. Inbreds {A ) and controls 



(B), 1906 to 1920. 



