MENDEL'S EXPLANATION 173 



top of the white when the pair is placed in its 

 column on the paper. This is supposed to represent 

 the dominance of red over white ; and if the pairs 

 of counters are placed on the paper so carefully that 

 the lower counter is in each case concealed, the 

 conclusion derived from a superficial glance at the 

 paper with the counters on it, will be that reds and 

 whites occur in the proportion of 75 per cent, and 

 25 per cent, respectively. Closer inspection of these 

 apparent reds will reveal the fact that, of these 

 seventy-five, fifty consist of a red and of a white 

 counter, and correspond to the hybrid individuals 

 bearing the dominant character ; and the remaining 

 twenty-five consist of two reds, and correspond to 

 the individuals which both bear, and breed true to, 

 the dominant character. 



This device brings home vividly to the spectator 

 the reason, according to the Mendelian theory, why 

 the recessive which appears in the second hybrid 

 generation, the extracted recessive as it is called, 

 breeds as true to the particular character under 

 consideration as the recessive with which the cross 

 was made. The extracted recessive breeds true for 

 precisely the same reason as the pure one does ; it 

 is the result of the union of like germ cells, or, to 

 speak more fully and accurately, of germ cells con- 

 taining factors for like characters. The factor for 

 dwarfness, for instance, contained in the ovule of a 

 hybrid tall pea is identical with such a factor borne 

 by a pure dwarf pea ; and when two such factors 

 borne by the hybrid tall unite and result in the 



