INHERITANCE IN ABNORMALITIES 



425 



individuals to 1 abnormal individuals in 21 generations. This 

 is a very low proportion indeed as compared with that for the 

 race as a whole (56 per cent). Moreover, every one of these 

 six races was entirely normal for some time before it died, as 



Chart 5 



Genetic history of six lines of Race A in which the selection of normals 



was continuous 

 ( n= normal; D = died out) 

 Feb. Mch. 

 27 1 3 5 7 9 11 13 15 17 19 21 23 25 27 



'4n /3n 4n 2n 4n D. 



\4n 4n 4n D. 

 4n 4n D. 



lab 

 r2n 2n 2n 4n 5n 4n 2n 4n 4n D. 

 3n \ 4n 4n 2n 2n 8n D. 



(7n In 4a 4n 4n 8n 4n 4n 2n 2n In D. 



Line 



A13bl In 



4n 



shown in the table. Figure 12 gives that part of the pedigree 

 of race A which includes these six lines. 



In 24 of the abnormal selected lines abnormals were produced 

 in every generation for some time and their selection was there- 

 fore continuous. The history of six of these lines is given in 

 chart 6. Table 11 gives the data from all of them. The largest 

 line was kept for 36 days after the selection of abnormals became 



Chart 6 



Genetic history of six of the lines of Race A in which the continuous selection of 



abnormals was made 

 ; (n = normal; ab = abnormal; D = died out) 

 December January 



21 23 25 27 2S 31 2 4 6 8 10 12 14 16 18 



2n In 



2ab 2ab 2ab lab 3ab lab lab lab lab D. 



In 

 lab 2ab lab lab D. 



In 

 lab lab lab lab D. 



2n 

 2ab 3ab lab D. 

 lab lab 4ab lab 2ab 2ab 2ab 2ab lab 2ab 4ab 2ab 2ab lab D. 



In In 

 lab lab lab lab lab lab lab lab lab D. 



