130 Maine: agricultural experiment station. 1913. 



87.5. If therefore, the coefFxients of Table i are plotted the 

 result will be the maximum limiting curve of inbreeding. 



Illustration II. Parent X Offspring Breeding. 

 The next illustration of the application of coefficients of in- 

 breeding will be the general case of back-crossing, that is the 

 mating of parent X offspring. 



The values of the successive coefficients for parent X off- 

 spring breeding for 16 ancestral generations are given in Table 

 2. 



Table 2. 



Values of the Successive Coefficients of Inbreeding in the Case 

 of Continued Parent X Offspring Mating. 



Coefficient of 



Ancestral Generations 



Numerical Value of 



Inbreeding. 



Included. 



• 



Coefficient. 



Zo 



1 







Zl 



2 



25 



Z2 



3 



50 



Z3 



4 



68.75 



Z4 



5 



81.25 



Z5 



6 



89.06 



Z6 



7 



93.75 



Z7 



8 



96.48 



Z8 



9 



98.05 



Z9 



10 



98.93 



Zio 



11 



99.41 



Zu 



12 



99.68 



Z12 



13 



99.83 



Zl3 



14 



99.91 



Zl4 



15 



99.95 



Zlo 



16 



99.97 



By comparison of this table with Table i it is evident that 

 while the increase in intensity of inbreeding is not so rapid in 

 the first few ancestral generations by this parent X offspring 

 type of breeding as with the brother X sister type, by the time 

 the loth ancestral generation is reached the values are, for 

 practical purposes, the same. 



Illustration III. 



The Pedigree of the Jersey Cow, Bess 

 Weaver (155121).* 



Leaving now the hypothetical cases we may consider some 

 pedigrees of actually existing animals. For a first illustration 

 of this sort the Jersey cow Bess Weaver may be taken. Her 

 pedigree through four ancestral generations is shown in pedi- 

 gree table II. 



