THE MEASUREMENT OF THE INTENSITY OF INBREEDING. 12/ 



to do directly with the gametic or zygotic constitution of indi- 

 viduals. 



5. Since the only possible infallible criterion of relationship 

 between individuals is common ancestry in some earlier genera- 

 tion, we are led to the practical rule, in measuring the degree 

 of inbreeding in a pedigree, to regard all different individuals 

 as entirely unrelated until the contrary is proved by the finding 

 of a common ancestor. This no doubt appears at this stage of 

 the discussion as an exceedingly obvious truism. The reader is 

 urged to accept it as such, and hold fast to it, because it will 

 help him over some apparent paradoxes later. 



The method of calculating coefficients of inbreeding, and their 

 real significance will be made much clearer by the considera- 

 tion of illustrative examples of tlieir application. To these we 

 may therefore turn. 



The Caecueation of Coefficients of Inbreeding. 

 We may first consider some simple hypothetical pedigrees. 



Pedigree Tabee I. (Hypothetical). 



To illustrate the Breeding of Brother X Sister, out of Brother 

 X Sister, Continued for a Series of Generations. 







e 



g 





h 







f 



g 







h 





d 



e 



g 





h 





f 



g 





h 





X 















c 



^ 



g 





h 







f 



Q 



b 



■ 



h 





d 



- 



g 







h 







i 



11 







ii 





