INHERITANCE OF PARTICULAR CHARACTERISTICS. 75 



WHITE VS. DARK Three different results may be, under differing condi- 

 tions, obtained. 



Dominance of White. This is the usual result. Two White Leghorns 

 crossed by a black Minorca produced only white hybrids, but the female 

 hybrids, at least, had some black feathers. White Leghorns crossed with 

 Houdans gave only white. White Leghorns crossed with a Red-backed 

 Game had white offspring with some buff on breast. On the other hand, 

 the white color of the Silky dominates over the dark color of the Frizzle 

 (Series XI) in about only 23 per cent of the hybrids. Bateson and Saunders 

 (1902, pp. 108-109), dividing all hybrids between black and white parents 

 into those of light type and those of dark type, conclude that the former 

 are to the later as 3.1 to i. Bateson and Punnett (1905, p. 117) conclude 

 that offspring of a pure white parent with colored or heterozygous (mixed) 

 birds are practically always prevailingly white. Hurst (1905, pp. 146-149) 

 gets chiefly white birds from crosses of White Leghorn hens with black or 

 mottled males. The exceptions may be due to the impurity of one of the 

 females. 



Barring. No barring resulted from crossing White Leghorn with Houdan 

 or black Minorca, or Silky with Frizzle. On the other hand, all males, and 

 only males, were barred in the hybrids of Tosa x White Cochin, and in. the 

 hybrids of White Leghorn Bantam and Rumpless Game barring occurred, 

 but among males only. Of 26 hybrids between Black Cochin and White 

 Leghorn, 8 were barred black and white, and these belonged equally to the 

 two sexes. Of n dark hybrids obtained by Hurst (1905, p. 133) from 

 White Leghorn x Houdan, 6 developed into black females and 5 into cuckoo 

 males. Apparently barring ("cuckoo marking" of the English) is asso- 

 ciated with maleuess. This result is curious enough, for, as Darwin pointed 

 out, in the ancestors of domestic poultry barring (or rather penciling) is 

 confined to the female sex. 



Barring is a heterozygous condition found in hybrids from a white and 

 a black parent. It is provisionally regarded as a form of participate inherit- 

 ance as opposed to the alternative inheritance of the Leghorn x Minorca 

 cross. This heterozygous condition when interbred usually breaks up into 

 white, uniformly pigmented, and barred again, as in the case of the Tosa 

 X White Cochin hybrids (p. 49). This form has in certain cases, as in the 

 Cuckoo Dorkings and in the Dominiques ancestors to the Plymouth Rocks 

 become truly mosaic, transmitting the mixture of qualities pure. The 

 method of fixing a heterozygous quality is still unknown to science.* 



* The experience of breeders of mice and guinea-pigs shows that white may be due to 

 the absence of an oxidizing ferment necessary to the bringing out of the color potential in a 

 chromogenic substance (c/. von Fiirth, 1903). If the chromogen is present the addition 

 (by crossing with a pigmented individual) of the ferment will reveal in the hybrid off- 

 spring the colors and pattern latent in the white parent. Working on this hypothesis, 

 we can judge of the latent patterns in the White Leghorn bantams and draw conclusions 



