CASE OF THE ANDALUSIAN FOWL 37 



idle prophecy ; for a difference between the hybrid 

 and the dominant parent has recently been detected 

 by the aid of the microscope in a stock instance of 

 simple dominance — roundness and wrinMedness in 

 peas. This will be described in detail in Chapter IX. 



If, therefore, we compare the two genealogical 

 tables (Frontispiece and Fig. 14), we see that the 

 Mendelian phenomena, as exhibited by these two 

 cases, are perfectly analogous. The only difference 

 between the two is that in one case (that of the peas) 

 the completeness of dominance of one character 

 makes it impossible to distinguish between dominants 

 and hybrids, so that the second hybrid generation 

 appears at first sight to consist of three individuals 

 bearing the dominant character, and one bearing the 

 recessive in every four, on the average ; and it is 

 not until we breed from these apparent dominants 

 that we discover that one of the three is a pure 

 dominant and the other two are hybrids. In fact, 

 it is only when we have raised the third hybrid 

 generation that we discover that the second hybrid 

 generation consists of one pure dominant, two 

 hybrids, and one recessive in every four. 



But in the case of the fowls, where the dominance 

 of black over white is incomplete, or, at any rate, 

 where the hybrid bears a colour which is peculiar to 

 itself, the real constitution of the second hybrid 

 generation (one pure dominant, two hybrids, and one 

 recessive) is apparent directly the individuals com- 

 posing it have been raised. 



If the Frontispiece and the Andalusian pedigree 



