THROWING BACK 79 



recessive character, the " fawn-and-white " type of 

 coloration may be called the dominant ; although 

 it may be argued that, in a sense, it is just as recessive 

 as albinism inasmuch as it disappears from the first 

 hybrid generation as much as albinism does ; but it 

 is convenient to speak of it as the dominant character, 

 and it is justifiable if we state the case by saying 

 that in the cross shown on Plate II. " some colour " 

 is dominant over " no colour " ; further, if the white 

 Andalusian is regarded as the recessive it is legitimate 

 to regard the white mouse as recessive, and, if this 

 is done, the fawn-and-white falls into its place as 

 the dominant. 



In all three cases — the pea, the fowl, and the 

 mouse — the two characters (of the two parents 

 respectively) reappear in the second hybrid generation 

 of which they each make up 25 per cent. ; the remain- 

 ing 50 per cent, being composed of individuals 

 resembling the hybrids of the first hybrid generation 

 in all three cases. The parental characters, when they 

 have reappeared in the second hybrid generation, 

 breed true without exception in the case of the 

 so-called " extracted " recessive ; and, with the 

 extremely rare exceptions afforded by the mice in 

 Group C, they also breed true in the case of the 

 "extracted" dominant. And in all three cases the 

 hybrids of the second hybrid generation again produce 

 the dominants, hybrids and recessives with the 

 exceptions afforded by the true-breeding mice in 

 Group B. 



We are thus again brought round to the conclusion 



