EFFECTS OF INBREEDING AND CROSSBREEDING. 



57 



measure of the efficiency of the families. There is good evidence for 

 differentiation in this in the second and third periods. There is also 

 rather close agreement with rank in resistance to tuberculosis. There 

 is not, however, agreement with longevity or with weight. 



Table 6. — The rank of five inbred families in various characteristics in three successive 

 periods, 1906 to 1910, 1911 to 1915, 1916 to 1919. 



[The correlations between these ranks in the first and second, the first and third, and the second and third 

 periods are shown below. The ranks of the families in longevity of males and females, born from 1915 

 to 1918, and in resistance to tuberculosis (1919-1920) are shown in the three columns at tbe right.] 





3 



© 



o 

 (-» 

 cd 



"SB 



co O 



So 



3 > 



S 



co 



u 



co 



1 

 I 



o 



■ag 



? © 



CO 



c3 

 <& 



CO 

 CO 



o 



03 



Adult 

 weight. 



& 



s 



o 



CD 



8 



>v 



t-l 



<V 

 Oh 

 co 

 CD 



8 



3 



M 



d 



o 



S 



CD 

 CO . 



2g 



5u0>> 

 PI 



3 



o 



Longevity. 



|.co 



si 



s 1 



to 0) 



Family. 



co 



CO 



"3 



3 



CO 



o 



S 



CO 



i 



i 



a 



3 



2 



5-5-5 

 4-2-4 

 1-4-2 

 2-3-3 

 3-1-1 



4-1-2 



2-2-3 

 3-5-5 

 5-3-1 

 1-4-4 



5-4-2 

 4-2-4 

 1-5-5 

 3-3-1 

 2-1-3 



2-5-5 

 1-1-1 

 3-3-3 

 4-2-2 

 5-4-4 



5-5-5 

 1-1-1 

 4-4-3 

 3-2-2 

 2-3-4 



2-5-4 

 1-1-1 

 4-4-5 

 3-2-2 

 5-3-3 



5-5-5 

 1-2-1 

 3-4-4 

 4-1-2 

 2-3-3 



4-4-4 

 1-2-1 

 2-5-5 

 3-1-2 

 5-3-3 



5-1-1 

 3-3-4 

 2-4-3 

 4-2-2 

 1-5-5 



5-4-2 

 1-2-3 

 2-5-4 

 4-1-1 

 3-3-5 



5-3-2 

 1-2-3 

 2-5-4 

 4-1-1 

 3-4-5 



-1 

 -3 

 -2 

 -4 

 -5 



-1 

 -2 



-3 

 -4 

 -5 



2 



13 



32 



35 



39 



-4 

 -3 

 -1 







Correlations. 

 lst-2d 



+0.10 

 + .70 

 + .60 



-0.30 

 - .70 

 + .70 



-0.10 

 - .50 



+ .20 



+0.30 

 + .30 

 +1.00 



+0.90 

 + .70 

 + .90 



+0.30 



+ .50 

 + .90 



+0.40 

 + .70 

 + .90 



+0.10 



-1.00 



0.00 



- .50 



+ .50 



-0.20 

 - .50 

 + .80 









lst-3d 



+ .30i- .90 

 + .90!+ .90 











2d-3d 























SUMMARY. 



Part II deals with the differences found among 23 inbred families, 

 derived wholly or in part from the same original line-bred stock. 



It is found that a certain color and pattern tended to become fixed 

 automatically in each line of descent. In certain cases an entire 

 family came to breed true to a given color and pattern. In other cases 

 subfamilies derived from different ma tings in the early generations of 

 a family each developed a characteristic color and type of pattern to 

 which they came to breed true. 



In a similar way, certain subfamilies became differentiated from 

 other subfamilies and from other families b}^ developing a strong ten- 

 dency toward reappearance of an ancestral fourth toe on the hind feet. 



Relatively few monstrosities were produced either by the inbred 

 families or by the controls. The tendency to produce a given type of 

 monstrosity has been characteristic of certain families. Such a 

 tendency has had no connection with the vigor of the family in other 

 respects. The two feeblest families gave few or no pronounced ab- 

 normalities, while about 30 per cent of the cyclopean monsters were 

 produced by the most vigorous family. Another family produced 

 most of the eyeless young and another had several defective young 

 with rudimentary legs. There was evidence of heredity within the 

 families, of the tendency to produce these abnormalities. There was 

 no evidence that inbreeding has any specific causal connection with 



