RELATING TO SECONDARY SEXUAL CHARACTERS 25 



spoken of as a blue bird, the hen only is entirely blue, while the male is 

 black above and blue below. The splashes on a white male correspond 

 to the black and blue of the Andalusian male, and are black if above 

 and blue if below. 



Lippincott found also that the blue birds differ from the black in two 

 characteristics, viz, in the blues the pigment is in larger masses, i. e., 

 it is more clumped, leaving more white between the clumps than in 

 the blacks, and in the blues the pigment is absent in the extremities 

 of the barbules. If the clumping and the condition of the barbules are 

 treated as separate entities, each gives a 3: 1 ratio. Lippincott con- 

 cludes, therefore, that the Andalusian cross is a 2-factor case. If each 

 of these characteristics was independent of the other in the sense that 

 some birds had clumped pigment and others deficiencies in the barbules, 

 then one might conclude that he was dealing with a 2-factor case ; but 

 if these two characters are only different aspects of the same gene, and 

 when one is present the other is also, the situation is not different from 

 those that are very common, viz, two or more effects produced by the 

 same genetic factor. 



Davenport has recorded results of crossing several breeds of different 

 colors (1906 and 1909). The white of the Leghorn was found dominant 

 to the black of the Minorca breed, although the hybrids, "at least the 

 females," had some black feathers. This white was also found to be 

 dominant to the mottled Houdan and to the "Red-backed game." 

 On the other hand, a male Tosa with wild-type plumage by recessive 

 White Cochin female gave " barred " males in F^ the barring coming 

 in, no doubt, from the Cochin and although not at the time recognized 

 by Davenport as sex-linked inheritance, the statement that barring 

 is "associated with maleness" (as already pointed out by Darwin) 

 indicated that the barring that appeared within the cross was probably 

 the sex-linked barring shown by other breeds. 



In Davenport's cross of White Leghorn by Minorca two blues 

 appeared (as stated above), indicating that the same factors were 

 here present that in the Andulusian white and black strain gives the 

 same result, 1 but why only some of the F x appear as blue, while others 

 are not blue, is not yet made clear, unless two factors for white were 

 present. White of the Leghorn breed was found not to be as com- 

 pletely dominant over buff as over black. Black was found dominant 

 over the wild-type (Black-Breasted game), but red is present in F! 

 birds also to some extent in those places where red is found in the game. 

 Lacing, as shown by the Dark Brahma, is dominant to the plumage 

 of the Tosa. Penciling also is said to be dominant, as shown in females 

 of the cross between the Dark Brahma and Tosa fowl. 



In his later paper (1909) Davenport gives fuller information in 

 regard to some of the F! cases reported in his first paper, as well as the 



1 Provided that the blue classification was based on the adult plumage and not on down color. 



