52 



Andalusian Fowl 



[CH. 



that the numbers from blue x blue average about i black : 

 2 blues : i splashed white. Both the blacks and the whites 

 extracted from blues breed true to their respective types, 

 black X black giving all blacks ; white x white giving 

 all whites again. When however black is bred with one of 

 these whites the offspring are all blues. There is thus no 

 doubt that the blue is the heterozygous form, while the 

 gametes bear either the blackness, or the whiteness. Ob- 

 viously in such a case, continued selection of blues will not 

 make them breed true. This can only come to pass if it 

 shall be found possible to get a blue bird in the gametes 

 of which the blue or intermediate character is carried as 

 a definite factor. These results may be represented in 

 tabular form thus : 



Blue X Blue 



"n 



n Blacks 



2n Blues 



I 



1 



\ 



n Splashed whites 



"1 



Blacks only n Blacks 2n Blues n Whites Splashed whites 



only 



Blacks only, 

 &c. 



Splashed whites 

 only, &c. 



Black X Splashed white 



I 

 Blues only 



n Blacks 



2n Blues n Splashed whites 



Such a case as this shows well what Mendel meant by 

 the *' hybrid-character." It is that character, or appearance, 

 or quality, which is produced by the meeting of the opposite 

 allelomorphs of the same pair in one zygote or individual. 

 The hybrid-character is a thing apart, which must always 

 be separately determined by experiment. Sometimes it is 

 indistinguishable from the dominant, sometimes, as here, 

 it is an appearance recognizably distinct from that of either 

 dominant or recessive. 



Prof J. Wilson (311) has shown that a similar rule pro- 

 bably holds in the case of shorthorn colours, where red- 



