C. J. Bond 115 



This heterochroraic blue and white tumbler-fan hybrid was mated 

 to a full sister, almond in colour with pink eyes, with the following 

 result : 



Blue and White x Almond 



Heterochromia s 



Bed ? 



r \ \ 1 1 



Blue Blue and White Almond Ahnond and White White 

 IS 14 2 4 6 



and the reappearance of heterochromia in some number unrecorded 

 of the blue and white birds. 



Thus it would seem that the mating of a self-colour black with pink 

 eye with a recessive white with " bull " eye is associated with the 

 appearance of broken-up feather colour pattern and a broken-up iris 

 anterior pigment pattern as in the Orkney rabbits. 



Moreover the irregular iris pattern is so far only found in the blue and 

 white birds, that is in birds of a dilute biack and white colour pattern. 



The gametic factor or factors, which in the self-coloured and self- 

 white parents control the whole feather pattern, and in the self-coloured 

 iris and the " bull " iris control the whole iris pattern, have undergone 

 some change by which in the birds with parti-coloured eye and feather 

 pattern they now control independently diflferent feather areas and 

 separate eyes and different portions of the iris in the same individual, 

 and the question arises. What is the nature of the change in the con- 

 stitution of these gametic factors which is responsible for this altered 

 behaviour of unit characters ? 



Harlequin feather colour pattern in pigeons. 



The result of mating two self black fantail cocks of prize strain with 

 orange red eyes from the same loft with two pure bred white fantail 

 hens with " bull " eyes in 1905 was to produce ^i hybrids of different 

 type in each case. In the "A" mating most of the Fi hybrids were 

 black and white piebalds with bull eyes, in the " B " mating all the Fi 

 hybrids were blacks with (in most cases) a few white feathers on the 

 rump and one or two white primaries in one wing. These black 

 hybrids had the orange red eye. [The details of these two matings 

 are given in the tables on pp. 118, 119.] 



But the point of interest is that the self mating of the Fi hetero- 

 zygotes of the "A" and " B" cross respectively resulted in a diflferent 

 proportion of extracted types in the F^ generation in each case, 

 although the proportion of selfs to pied, two to one, was about equal 



