418 Scientific Proceedings, Royal Dublin Society. 



(i) Wliole-coloured j'ellow rabbits were mated with Himalayan rabbits 

 which are white with black " points."' The first crosses were whole-coloured 

 agoutis. Thus, whole colour is dominant to the Himalayan pattern. 



The second crosses were agouti (27), yellow (9), black (9), tortoiseshell 

 (3), and Himalayan (16). The whole-coloured rabbits are thus — agouti (9) 

 : yellow (3) : black (3) : tortoiseshell (1). Black and yellow are thus 

 dominants : together they produce agouti, and their recessives together 

 produce tortoiseshell. 



The three pairs of factors concerned in the case are thus : — 



F, which produces Tellow when concurrent with h, and its recessive tj. 

 B, which produces Black when concurrent with y, and its recessive h. 

 W, Whole colour, and its recessive //, Himalayan pattern. 



Their second crosses will be represented by the following scheme : — 



T B W = whole-coloured agoutis, . .27 



Y B h = Himalayan agoutis, . . .9 



Y b W = whole-coloured yellow, . . 9 

 y B W = whole-coloured blacks, . . 9 

 y b W = whole-coloured tortoiseshells, . 3 

 y B h = Himalayan blacks, ... 3 



Y b h = Himalayan yellows, ... 3 

 y b li = Himalayan .tortoiseshells, . . 1 



(ii) Black barb pigeons were mated with wliite fantails.^ The first 

 crosses were black witli white splashes. Tlius splashing was dominant to the 

 plain colour, and had been carried, though obscured, by the white fantails. 

 Thus, also, black seemed dominant to white, but the second crosses revealed 

 the white fantails to be carrying another obscured character, namely, blue 

 which is black's recessive. There were 9 blacks : 3 blues : 4 whites. It is 

 a case similar to Hurst's rabbits, and may be represented thus : — 

 Black (9) Blue (3) Black albino (3) Blue albino (I) 



C a a 



B bl B hi 



The three pairs of factors are — 



C, colour and its recessive a, albino. 

 B, black and its recessive hi, blue. 

 S, splashed and its recessive }->, plain. 



1 Punnett, p. 56, 2 Punnett, p. 60. 



