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THE AMERICAN NATURALIST [Vol. LII 



splashed, exact data on this mating, as well as on the back 

 crosses to black and blue- splashed, are really very mea- 

 ger. Bateson and Saunders (1902, p. 131) first sug- 

 gested that the blue Andalusian was probably a hetero- 

 zygote. Bateson and Punnett (1905, p. 118) quoted Mrs. 

 Blacket Gill, a fancier of blue Andalusians, to the effect 

 that blues mated to blues gave 22 blacks, 36 blues and 17 

 white-splashed (i. e., blue-splashed). They secured stock 

 from Mrs. Gill and made matings which gave the follow- 

 ing results : 



By the blue 3 the white 2 gave 34 blue, 20 white-splashed, and the 

 black 2 gave 27 blue, 19 black. In each case the result is qualitatively 

 what would be expected if the blue is a heterozygote of black X splashed 

 white [italics mine] ; but whether the departure from equality indicates 

 that some gametes bear the unsegregated blue, or may merely be taken 

 as individual irregularities, can not yet be stated. 



The same blue cock was bred with a black hen from Experiment 40 

 (in which the dark birds were unexpected), F 2 , from White Wyandotte 

 X Wh. Legh., giving as offspring 10 black, 15 slaty black to bluish. 

 Hence, therefore, it is evident that the black ? was a homozygous black. 

 The 10 blacks are the result of the union of the black gametes from the 

 Andalusian d 1 with those of the ?, and the 15 slaty resulted from the 

 meeting of the black of the hen with the white-splashed from the 

 Andalusian. 



Bateson and Punnett (1906, p. 20) give the following 

 summary of the data upon which the case of the blue An- 

 dalusian largely rests at the present time. 



In Report I it was suggested that the blue colour of the AiHlahi-ian 

 is probably heterozygous, and in Report II (p. 118) figures were given 

 in support of this view. During the past two years additional evidence 

 has been acquired, and every form of mating has now been tested, with 

 the following results: 



