THE PROBLEM OF INBREEDING 103 



to a high degree. Probably no experimentalist's 

 records of descent are more accurate, considering 

 the relative numbers involved in the two cases. 



The real need, I venture to think, has been for 

 an appropriate and valid method of pedigree 

 analysis, which possessed generality, and could on 

 that account be depended on to give comparable 

 results when applied to two (or more) different 

 pedigrees. Specifically, there seems not to have 

 been worked out any adequate general method of 

 measuring quantitatively the degree of inbreeding 

 which is exhibited in a particular pedigree. Without 

 such a measure it is clearly impossible to proceed far 

 in the analysis of the kinship aspect of inbreeding. 



It is the purpose of this paper to present a 

 method for measuring and expressing numerically, 

 in the form of coefficients, the degree of inbreeding 

 which exists in any particular case. I shall 

 endeavor to show that the method is (a) unique, 

 in the sense that the values obtained in any par- 

 ticular instance can only be affected by the degree 

 or amount of inbreeding which has been practiced 

 in the line of descent under consideration, and 

 (b) general, in the sense that it is equally applicable 

 to all pedigrees and to all degrees and types of in- 

 breeding. 



PRELIMINARY DEFINITIONS 



In attempting any general analysis of the prob- 

 lem of inbreeding from the theoretical stand- 



