144 MODES OF RESEARCH IN GENETICS 



so evident as to need no elaboration. It has been 

 brought out by East and Hayes. 1 



The values of the K's for a particular pedigree 

 evidently furnish a rough index of the probability 

 that the two germ plasms which unite to form an 

 individual are alike in their constitution. This 

 will follow because of the fact that the probability 

 of likeness of germinal constitution in two indi- 

 viduals must tend to increase as the number of 

 ancestors common to the two increases. Just 

 what is the law of this increase in probability is 

 a problem in Mendelian mathematics which has 

 not yet been worked out. The general fact, 

 however, seems quite sure. 



From the above discussion it seems plain that in 

 reaching a numerical measure of the degree of 

 inbreeding it is not sufficient to consider coefficients 

 of inbreeding alone. The coefficients of relation- 

 ship must also be taken into account. 



It is suggested that the two constants be written 

 together for each generation, the coefficient of 

 inbreeding being followed by the coefficient of 

 relationship in brackets. 



Thus we have 



Inbreeding and Relationship Coefficients of 

 King Melia Rioter 14th 



z (Ki) = o (o) 



Z 1 (K a ) = 25 (0) 



1 U. S. Dept. Agr. Bur. Plant Industry, Bui. 243, 1912. 



