60 BULLETIN 1090, U. S. DEPARTMENT OE AGRICULTURE. 



Table 8. — Data on the fertility of the different inbred families, 1911 to 1915. 



Fam- 



Size of litter. 



Num- 

 ber of 

 mating- 

 years. 



Num- 

 ber of 

 litters. 



Num- 

 ber of 

 young. 



Aver- 

 age 

 size of 

 litter. 



Litters 

 per 

 year. 



Young 



ily- 



1 



2 



3 



4 



5 



6 



7 



year. 



1 



16 

 42 

 19 



11 

 97 

 30 



83 

 33 











12.6 

 64.7 



34 



246 

 94 



59 

 589 

 235 



1.74 

 2.39 

 2.50 



2.70 

 3.80 

 3.63 



4.68 



2.... 



16 

 6 



8 

 4 







9.10 



3.... 



1 



1 



25.9 



9.07 



7 



49 



67 



70 



33 



11 



3 



1 



67.6 



234 



605 



2.58 



3.46 



8.95 



9.... 



26 



46 



58 



30 



7 



5 





55.2 



172 



477 



2.77 



3.12 



8.64 



11.... 



17 



38 



54 



36 



9 



1 





53.8 



155 



450 



2.90 



2.88 



8.36 



13.... 



42 



96 



134 



63 



12 



3 





100.7 



350 



966 



2.76 



3.48 



9.59 



14 



12 



21 



2 



117 



26 

 1 

 72 



7 









25.9 

 1.2 



88.3 



66 



3 



306 



160 



7 



716 



2.42 



2.55 



6.18 



15 











17.... 



71 



38 



6 



1 



1 



2.34 



3.47 



8.11 



18.... 



32 



72 



46 



23 



6 



2 



1 



51.8 



182 



455 



2.50 



3.51 



8.78 



19.... 



24 



35 



41 



23 



5 



3 





37.5 



131 



352 



2.69 



3.49 



9.39 



20.... 



27 



61 



52 



15 



6 





i 



51.2 



162 



402 



2.48 



3.16 



7.85 



21.... 



49 

 41 



61 

 47 



28 

 43 



8 

 14 



2 

 6 







41.2 



148 

 151 



297 

 350 



2.01 

 2.32 



3.59 

 3.80 



7.21 



23.... 







39.7 



8.82 



24.... 



49 



55 



39 



15 



4 





i 



46.1 



163 



363 



2.23 



3.54 



7.87 



31.... 



33 



39 



52 



28 



8 



5 





56.9 



165 



449 



2.72 



2.90 



7.89 



32.... 



50 



107 



84 



26 



6 



1 





78.9 



274 



656 



2.39 



3.47 



8.31 



34 



20 

 49 



31 



90 



22 



97 



13 



64 



2 

 15 







28.7 



87.2 



88 

 325 



210 

 912 



2.39 

 2.81 



3.07 

 3.73 



7.32 



35.... 



9 



l 



10.48 



36.... 



50 



107 



88 



42 



6 



3 





86.1 



296 



744 



2.51 



3.44 



8.64 



38.... 



25 



45 



59 



21 



6 



2 





62.6 



154 



418 



2.71 



2.46 



6.68 



39.... 



37 



91 



110 



44 



14 





l 



87.0 



297 



802 



2.70 



3.41 



9.22 



Table 9. — The percentage born alive in the different inbred families. 



[The average in litters of each size and an index (litters of 1,2, 3, and 4, weighted 1, 3, 4, and 2 respec- 

 tively), 1906 to 1910 and 1911 to 1915.] 







Size of litter, 1906-1910. 









Size oflittei 



, 1911- 



1915. 







Fam- 















Index. 















In- 



ily. 



























dex. 





1 



2 



3 



4 



5 



6 





1 



2 



3 



4 



5 



6 







Per 



Per 



Per 



Per 



Per 



Per 





Per 



Per 



Per 



Per 



Per 



Per 







c't. 



c't. 



c't. 



c't. 



c't. 



c't. 





c't. 



c't. 



c't. 



c't. 



c't. 



c't. 





1 



100.0 

 72.7 



76.9 

 82.5 



95.6 



88.1 



91.7 

 75.0 



100.0 

 94.3 



"82." 3' 



89.7 

 82.3 



68.8 

 81.0 



95.5 

 90.2 



85.7 

 84.3 









85.9 



2.... 



76.6 



72. 5 





84.2 



3.... 



76.9 



79.3 



83.7 



81.0 



95.0 



43.3 



81.2 



84.2 



83.3 



82.8 



50.0 



20.0 



00.0 



76.5 



7.... 



85.7 



85.1 



87.7 



77.0 



70.9 



50.0 



84.6 



81.6 



83.6 



81.4 



83.3 



72.7 



61.1 



82.5 



9.... 



84.6 



90.5 



84.8 



81.7 



85.0 



94.4 



85.9 



80.8 



84.8 



78.7 



83.3 



77.2 



50.0 



81.7 



11 



70.6 



90.2 



88.2 



84.4 



78.1 



63.3 



86.3 



76.5 



89.5 



88.3 



66.7 



48.9 



83.3 



83.2 



13.... 



79.0 



88.7 



88.5 



88.2 



86.0 



73.3 



87.6 



90.5 



87.5 



89.8 



85.3 



78.3 



94.4 



88.3 



14 



84.2 

 83.3 

 96.0 



80.5 

 78.6 

 95.2 



87.0 

 77.3 

 92.5 



82.4 

 78.1 

 92.1 



82.2 

 00.0 

 95.7 



33.3 



"<ii.T 



83.9 

 78.5 

 93.6 



83.3 

 "83.T 



90.5 

 50.0 

 93.6 



76.9 

 66.7 

 89.4 



67.9 







79.8 



15 









17 



82.9 



50.0 



83.3 



88.7 



18.... 



85.7 



90.3 



96.8 



95.8 



77.2 



90.0 



93.5 



75.0 



90.3 



92.0 



87.0 



53.3 



33.3 



88.8 



19.... 



90.9 



77.3 



87.9 



85.0 



92.0 





84.4 



91.7 



94.3 



77.2 



60.9 



80.0 



61.1 



80.5 



20.... 



85.0 



84.3 



85.4 



86.1 



90.0 



6i. i 



85.2 



85.2 



85. 2 



89.1 



93.3 



83.3 





88.4 



21.... 



100.0 



88.0 



91.3 



94.4 



70.0 





91.8 



75. 5 



82.8 



85.7 



71.0 



10.0 





81.1 



23.... 



81.8 



96.4 



93.8 



95.5 



88.6 



66.7 



93.7 



80.5 



87.2 



93.8 



92.9 



90.0 





93.3 



24.... 



87.0 



90.0 



89.3 



85.0 



78.2 



91.7 



88.4 



67.4 



75.5 



82.9 



78.3 



40.0 





78.2 



31.... 



94.7 



96.7 



93.5 



93.8 



71.4 



41.7 



94.6 



66.7 



89.8 



78.2 



91.1 



95.0 



83.3 



83.1 



32.... 



95 4 



92.7 



90.6 



84.9 



72.2 



66.7 



90.6 



94.0 



85.5 



89.7 



71.2 



56.7 



16.7 



85.2 



34.... 



50.0 



95.0 



93.3 



93.8 



75.0 





89.6 



75.0 



90.3 



90.9 



84.6 



40.0 





87.9 



35.... 



82,6 



98.8 



93.3 



75.0 



60.0 



70.0 



90.2 



71.4 



8S. 9 



91.7 



83.2 



64.0 



46.2 



87.1 



36.... 



93.3 



94.3 



86.9 



78.0 



81.9 



90.0 



89.0 



92.0 



91.6 



87.9 



73.2 



60.0 



55.6 



86.5 



38.... 



93.3 



93.6 



97.0 



84.5 



86.7 



83.3 



93.1 



88.0 



93.3 



92.7 



77.4 



53.3 



50.0 



89.4 



39.... 



90.9 



94.8 



84.3 



85.7 



0.0 



0.0 



88.4 



94.6 



94.0 



91.8 



85.8 



64.3 





91.5 



