THE PROBLEM OF INBREEDING 123 



The calculation is carried out in accordance with 

 the same principles as have been illustrated in the 

 previous cases. We have, from Pedigree Table III, 



7 100 (2-2) . 



3 " ~~2~ ' 



and 



z _ 10 Q (4-4) _ Q> 



since in generations 1 and 2 there are two and 

 four different ancestors respectively. 



25, 



since in generation 3 the two individuals g and h 

 each appear twice, and by our rule any ancestor 

 is only counted once. 



) = 50, 



16 



since in generation 4 the individuals ra and n 

 appear four times and are only counted as different 

 ancestors once each, and individuals o and p each 

 appear twice. 



The data of Table 3 are given graphically in 

 Fig. 1, together with the curve for brother X 

 sister and parent x offspring. 



From the table and figure it is seen that with 

 continued inbreeding according to any one of these 

 four types the coefficient approaches the value 



