142 MODES OF RESEARCH IN GENETICS 



related to each other. Community of ancestry 

 is the basis of kinship. 



Percentages derived in the way shown above, 

 from cross pedigree elimination tables, I have 

 called coefficients of relationship, and designated 

 by the letter K, with appropriate sub-numbers 

 referring to the generation. These relationship 

 coefficients are, with some limitations, independent 

 of the inbreeding coefficients in the values they 

 may take, though the two will usually be corre- 

 lated to some degree. It is, however, possible 

 to have a high value of Z with K = 0. 



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 = 0. 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 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 

 X sister breeding. Clearly K would be 0, since 

 no animal on one half of the pedigree could ever 

 appear on the other. The values of the successive 

 coefficients of inbreeding (Z's) in such a case 

 are shown in Table 9, where they are com- 

 pared with the coefficients of inbreeding in com- 



