R. Staples-Browne 161 



were dark it was concluded that they would have been of the dark 

 type had they lived. It was noticed that dark birds had dark beaks 

 and legs, and white birds had white beaks and legs which could be 

 distinguished in the next. From the second pair of eggs one bird was 

 obtained which died twenty days after hatching, and was definitely of 

 the dark type. The second year five pairs of eggs were laid, but from 

 these only one bird was hatched. This died the next day but it was 

 seen that the beak and legs were dark. All the other eggs were either 

 broken by the parents or forsaken by them at an early age, and it was 

 considered useless to attempt to breed from these birds again. 



From the second experiment (No. 84) a very clear result was 

 obtained. Six birds were hatched aud all matured and were dissected 

 for sex. There is absolutely no question of the purity of the Turtle $ 

 as it was taken from the nest of a wild bird, and the mating con- 

 clusively shows the sex-limited inheritance of white in these species, 

 for the result obtained was 4 dark (/s and 2 white $s. 



White $ xBarbary J'. (Exps. 85—88.) The first two of these 

 matings give the expected result, viz. a uniform generation of dark F^'s. 

 Fourteen birds were produced, all of the Barbary type. From Exps. 

 87 and 88, however, a mixed generation occurred consisting of 4 dark 

 c("s, 5 dark $ s, 3 white j/s and 3 white $ s when the offspring of the 

 two pairs were added together. I think there is little doubt but that 

 the Barbary ^^s were in both cases heterozygous and contained white. 

 The family produced from Exp. 87 is exactly what would be expected 

 from such a mating, and no doubt had Exp. 88 been continued more 

 whites would have been produced, so that an equality of dark and 

 white birds would have resulted. 



Barbary $ x White J'. (Exps. 89 — 91.) With one exception the 

 results obtained from these matings are dark J's and white ?s. 

 Eighteen Barbary J's and seventeen white $s were produced. But 

 in addition one dark $ was raised in Exp. 90. This is a parallel case 

 to the black-eyed $ s which Miss Durham obtained from the mating of 

 black-eyed Canary ^ s with cinnamon Canary J's, as recorded by her in 

 Report to the Evolution Committee of the Royal Society, iv. 1908. 

 The occurrence of the dark female form in .f, is exceptional, and further 

 work is required to explain its appearance. 



The foregoing experiments are, however, sufficient to show that a 

 sex-limited inheritance of white occurs in the races of doves under 

 consideration. 



