No. 562] THE PROBLEM OF INBREEDING 601 



Pedigree Table XVI— Continuation of VII 



Jung- 



| Ethel 







Gen. 











1 

 8 

 1 



f Robert Tell ' 

 [ • Minnie 



J • Wrn. Tell 









9 



than that indicated; it may have been more. Whether it 

 was or not is not a question open to scientific determina- 

 tion but only to speculation. Furthermore, of course, 

 experimental breeding with "wild" animals is on exactly 

 the same footing as herd-book work in regard to this 

 point. Every experiment must bcf/in somewhere with 

 unknown stock. 



In the twelfth ancestral generation the theoretically 

 possible number of different ancestors is 4,096. In a rela- 

 tively long pedigree like that of Saxton it would obviously 

 be an extremely tedious business to determine the value of 

 q by direct counting, as has been done in the preceding 

 simpler illustrations. The calculation of the coefficients 

 of inbreeding may he greatly simplified in the case of long 

 pedigrees by a system of counting which makes the line 

 of descent the unit rather than the individual. This sys- 

 tem is used in the above pedigree. While each individual 

 animal which is eliminated because of previous appear- 

 ances in a lower ancestral generation is marked with an 

 X, those at the apex of a line of descent are marked 

 with a solid circle. These latter are all that need to be 

 counted directly. Their elimination automatically elimi- 



