No. 610] SHORTER ARTICLES AND DISCUSSION 637 



Upon consideration it appears that the real measure of com- 

 parative amount or degree of inbreeding, considering the pedi- 

 gree as a whole, is given by the area included by the particular 

 inbreeding curve under discussion, as compared with the corre- 

 sponding area of the maximum (brother X sister) curve. Thus 

 in Fig. 1, Saxton is less inbred than the maximum possible 

 amount to an extent proportionate to the amount by which the 

 area T (a c d) is smaller than the area M (aid). This con- 

 sideration gives us the desired method of uniquely expressing 

 the total amount or degree of inbreeding. It only remains to 

 consider practical methods of calculation. 



3. Theoretically one should integrate the maximum (brother 

 X sister) curve, and the observed curve, and compare the areas 

 derived from such integrations. Practically this is not possible, 

 because many observed curves of inbreeding can not be fitted by 



