80 BIE. R. STAPLES-BROWNE OX [Feb. 18, 



well as two or thi-ee tail-feathers and some under tail-coverts. 

 One bird had only two white tail-feathers and some white on the 

 vent. Another (No. 51 F. 3) had only a very few white feathers 

 at the vent. This bird, however, when mated to a blue without 

 white (v. Exp. 10) produced young with white feathers. (The 

 matings of these several young are shown in Exps. 10, 11, 14, 

 15, 17, 18, 21, 27, 28, and^'Sl.) 



F, 4 Generation. 



Exp. 10.— F. 3 Blue § 97 x F. 3 Blue with very few white 

 feathers c? 51. 



These birds were raised in Exp. 9. Four young were reared 

 from this cross, of which three showed no white feathers, and the 

 fourth had one white flight-feather, and a large patch of white on 

 the vent and left thigh. In addition to these, two young birds 

 were hatched but died at the age of 1 days : on one of these 

 white quills were seen on the abdomen, but on the other no 

 white quills were visible. From the above it appears that the $ 

 bird was homozygous in respect of the blue colour, but that the 

 (S contained white. Unfortunately the three F. 3 birds which 

 showed no white were all $ 's. 



Exp. 11.— F. 3 Blue w. f. $ 52 x F. 3 blue w. f, ^ 13. 



In this experiment two of the birds with white feathers raised 

 in Exp. 9 were mated together. Eleven young were raised, of 

 which 9 were bkie with white feathers and 2 were white. Of 

 the blues with white feathers six showed much white ; the 

 white being in the same situations as in the F. 3 birds but more 

 extensive. There was much white on the head and neck, the 

 back and breast were in some cases mottled. The flight-feathers 

 were mostly white up to the number of 29, and many tail- 

 feathers up to 18, and several under tail-coverts. The whole 

 appearance presented was a blue bird mottled with white. The 

 other three blues, however, had only a few white feathers. 



No. 15, F. 4, had only a few white feathers on the head and a 

 small patch on the abdomen and vent. This bird, how- 

 ever, was subsequently proved to contain white (see 

 Exps. 19 and 22). 

 No. 22, F. 4, had a small patch on the vent and thighs, two 



white tail-feathers, and a few under tail-coverts. 

 No. 76, F. 4, had a small streak of white behind the eyes, and 



two white feathers at the vent. 

 It will be noticed that no blues without white were raised in 

 this experiment as was anticipated. This result may be compared 

 with those of Exps. 24, 25, and 26, in which birds i-aised from the 

 matings of the heterozygotes with whites did not produce the 

 expected number of blues without white when mated together. 

 Matings in the direct line have not been carried beyond this 

 sjeneration. 



