232 MAINE AGRICULTURAL EXPERIMENT STATION. I915. 



From this table it appears that the values of the coefficients 

 of inbreeding will be exactly the same for this type of mating 

 as in the case of single cousin mating. In other words the in- 

 breeding is of the same degree of intensity if uncle is bred with 

 niece, or nephew with aunt, as if single first cousins are mated 

 together. 



From the data presented in this and former papers it is clear 

 that inbreeding continued for about ten generations, quite regard- 

 less of the type of mating, provided only it be continuously fol- 

 lowed, leads to within one or two per cent, of complete "con- 

 centration of blood." The bearing of this result upon the gen- 

 eral question of the degree of inbreeding which exists in the 

 ancestry of our domestic animals today is obvious. To consider 

 but a single case: In 1789* a law was passed prohibiting the 

 importation of cattle into the Island of Jersey. Hence it fol- 

 lows that all pure-bred Jersey cattle of the present time must 

 be of the descendants of the relatively few animals on the 

 Island in 1790. Taking three years as about the average gen- 

 eration interval in cattle, this means about forty generations 

 since the Island was closed to importation. The concentration 

 of lines of descent which must have occurred in this time merely 

 by the dropping of lines and quite regardless of the type of 

 mating is obvious. This is not the place to go in detail into the 

 discussion of inbreeding in Jerseys, especially as the writer hopes 

 shortly to publish the results of an extensive study of this mat- 

 ter, but it seems desirable to emphasize the bearing of such 

 hypothetical pedigrees for particular types of mating as are 

 given in this and earlier papers, on the general problem of 

 inbreeding. 



*Teste Rees's Encyclopedia and H. S. Redfield, Natl, Stockman and 

 Farmer. December 15, 1892. 



