THE PROBLEM OF INBREEDING 139 



From this we have, for the inbreeding coeffi- 

 cients, 



These facts will possibly be made clearer to 

 those not actually working much with pedigrees 

 by Table VII, which gives the first four ancestral 

 generations l of the pedigree of King Melia Rioter 

 14th. 



Generalizing the above reasoning we get the 

 following result : 



In A S9 and higher ancestral generations, f = 

 50.00 per cent of the dam's ancestors are animals 

 which are also ancestors of the sire. 



1 In the study of pedigrees stress is naturally laid on the ancestral 

 generations, rather than on the filial, as in breeding experiments. 

 It becomes very convenient to have a brief designation for ancestral 

 generations, in the same way that Fi, F 2 , etc., are used to denote 

 filial generations. I would suggest the use of the letter A with sub- 

 numbers for this purpose. We then have A\ denoting the parental 

 generation, A 2 the grandparental, A 3 the great-grand-parental, etc. 



