238 BREEDING 



Only the ratio of the greens to the yellows is inserted 

 in the bottom line of the pedigree, because the con- 

 stitution of the yellows has not been determined. 

 Nor does it concern us here. 



The result of this experiment, therefore, shows 

 that, if we confine our attention to one pair of cha- 

 racters at a time, the attempt to predict the result of 

 a given union must be based on a knowledge of the 

 factors representing these characters in the germ-cells 

 of the two individuals mated, and that the only know- 

 ledge of the characters of their ancestors which is 

 required is such as is necessary to discover what these 

 factors are. 



Besides supporting this general thesis, the result 

 of this experiment tests another corollary of equal 

 practical interest which follows from the Mendelian 

 theory. It tests the truth of the assertion that an 

 " extracted " individual in any generation is as pure 

 in respect of the character which it bears as an 

 individual in a pure strain characterised by this 

 feature. For instance, it tests the truth of the 

 statement that an extracted green in the fifth hybrid 

 generation is identical in respect of its greenness 

 with a pure green, and it proves that this statement 

 is correct. Not only is the colour of such an extracted 

 green apparently identical with a green of a pure 

 strain, but its breeding properties are identical, as 

 shown by the result of mating it with a pure yellow. 

 This conclusion is merely, however, an instance of 

 the special application of the general conclusion set 

 forth in the last paragraph. 



