240 MAINE AGRICULTURAL EXPERIMENT STATION. I915. 



TABLE 7. 



Comparing the Maximum Possible. Values of the Coefficients of 

 Inbreeding (Z) when the Coefficie;nt of Relationship K Equals 

 (a) Zero, and (b) lOO. 



Generation Maximum Possible Value Maximum Possible Value 



of Z when K "^ o of Z when K = 100 



Ai • o 



A, 50.00 



As 50.00 75-00 



A4 75-CO 87.50 



A5 87.50 93-75 



A3 93-75 96.88 



At " 96-88 98.44 



As 98.44 99.22 



A9 99.22 99.61 



Aio 99.61 99.80 



The most important feature of the relationship coefficients is 

 found in their genetic implications. This can be indicated best 

 by an illustration. Let us consider the case of the maximum 

 possible degree of inbreeding with K = o. This will be found 

 when the sire and the dam are each inbred to the highest possible 

 degree (continued brother X sister mating) but are in no way 

 related to each other. Such a case would be afforded, for 

 example, if a Jersey bull, the product of continued brother X 

 sister mating, was bred to a Holstein cow, which was also the 

 product of a continued brother by sister breeding. Clearly K 

 would be o, since no animal on one half of the pedigree could 

 even appear on the other. The values of the successive coeffi- 

 cients of inbreeding (Z's) in such a case are shown in Table 7, 

 where they are compared with the coefficients of inbreeding in 

 complete continued brother X sister mating, where K = 100.'' 



From this it appears that an individual may be inbred in 10 

 generations to ivithin two-tefiths of one per cent, as intensely, 

 measured by the coefficients of inbreeding, if his sire and dam 

 are in no zvav related, as he would be if his sire and dam were 

 brother and sister. But clearly the germinal constitution of the 

 individual produced would, except by the most remote chance, 

 be quite different in the two cases. 



'Since, of course, all of a sister's ancestors are identical with her 

 brother's. 



