CONSANGUINITY 393 



hereditary predisposition to disease to start with, then the evil 

 results of inbreeding will soon be evident. But the point is, 

 what will happen if the stock be healthy ? 



Extensive experiments by Castle and others on the inbreeding 

 of the pomace-fly, Drosophila ampelophila, led to the general 

 result that " inbreeding probably reduces very slightly the 

 productiveness of Drosophila, but the productiveness may be 

 fully maintained under constant inbreeding (brother and sister) 

 if selection be made from the more productive families." 



It seems well established that some stable and important 

 breeds of cattle — e.g. polled Angus — have arisen under conditions 

 involving in the early stages extremely close inbreeding, and it 

 is well known in horse-breeding that very valuable results have 

 been reached by using the same stallion repeatedly on successive 

 generations. 



Thus, if we take the pedigree of the short-horn bull 

 "Courtier," calved January 6th, i8g6, owned by the Iowa 

 Agricultural College, we find from the tabulation given by Mr. 

 R. W. Barclay that "Champion of England" (17526) appears 

 in the pedigree over twenty-five times, and " on both sides of 

 the house." We find another famous bull, " Roan Gauntlet " 

 (45276), functioning over and over again in the lineage. Let us 

 take, for instance, the pedigree of the paternal grandfather of 

 "Courtier" (See p. 394). 



