THE PROBLEM OF INBREEDING 139 



From this we have, for the inbreeding coeflB- 



cients, „ 



Zo = 



Zi = 25.00 



Z2 = 25.00 



Zz = 37.50 



Z4 = 50.00 



Z5 = 71.88 



Zg = 81.25 



Z7 = 90.63 



Zs = 92.77 



Z9 = 93.65 



Zio = 93.85 



Zii = 93.85 



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 ^ of the pedigree of King Melia Rioter 

 14th. 



Generalizing the above reasoning we get the 

 following result : 



In A3, and higher ancestral generations, f = 

 50.00 per cent of the dam's ancestors are animals 

 which are also ancestors of the sire. 



* 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, F2, 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 Ai denoting the parental 

 generation, A2 the grandparental, Az the great-grand-parental, etc. 



