38 BREEDING 



are folded out and compared it will be seen tliat the 

 two are fundamentally the same, and correspond with 

 one another individual for individual. The point in 

 which they differ is an unessential feature of the 

 Mendelian phenomenon — namely, the matter of 

 dominance. The fact that the dominant and hybrid 

 tall appear to us identical is probably no more than 

 a measure of the crudeness of the means which have 

 hitherto been adopted to distinguish between them 

 — observation by the naked eye. 



The point in which the two tables agree is the 

 essential feature in Mendelian inheritance, and con- 

 sists in the orderly reappearance of the characters 

 of the two varieties crossed, amongst the progeny of 

 the cross, in definite numerical ratios and in a state 

 as pure as that in which they existed in the two' 

 parental varieties before the cross was made. The 

 term Segregation is commonly used to denote this 

 splitting ont of the parental characters amongst the 

 offspring of hybrids. 



We may obtain some idea of the value of a know- 

 ledge of the Mendelian phenomenon to the practical 

 breeder by comparing the fate of a would-be breeder 

 of Andalusians who possessed this knowledge with that 

 of one who did not. The breeder who had not heard 

 of the Mendelian discovery, or had heard of it and 

 had rejected it as contrary to common sense, would 

 continue to breed from his Andalusians from genera- 

 tion to generation in the hope that ultimately he 

 would eradicate the black and also the white taint. 

 But he would never obtain more than 50 per cent. 



