28 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



with patches of pure white," and was so remarkable as to be separately described 

 later. The male listed as " to be of light color " died at 6 days, and it seems possible 

 that this early prognosis of color was wrong. At any rate, the author later records 

 (R 16) this cross as exhibiting sex-limited inheritance. It may be pointed out that 

 this type of heredity in a cross between species of diEeront families has not hitherto 

 been reported. The two parents are shown in pi. 3; a darker male hybrid and 

 one of the light females from this pair are also shown in the same plate. 



The data (fully given in table 15) show that from this cross all of the 18 eggs 

 of the first year were hatched — a very remarkable result in the light of what has 

 been seen of the results of pure individuals of Columba crossed with pure individuals 

 of Turtur. We meet here, too, the further interesting fact that though all of the 

 eggs are capable of hatching, the term of life of the young is limited to quite the 

 same period as were the offspring of pure Columba x pure Turtur (see tables 1, 2 

 and 3). This period for 11 young of the first year was 1 to 22 days after hatching, 

 and the 6 hatches of the following year all fell within this same period. The life- 

 term of birds from eggs laid in May of the first year forms a notable exception; 

 6 birds from the 6 eggs of this period produced birds that lived from several months 

 to more than 3 years, and 1 male from this group is still alive at nearly 7 years. 

 Immediately following this group, 1 young lived 64 days, and then the term of 

 life again fell to a few days. 



The abnormalities met with in those earlier (pure Columba x pure Turtur) 

 crosses, moreover, promptly reappear in this record. There are three or probably 

 four groups of such abnormalities. The first of these is the already familiar 

 abnormal legs, these being short and directed backward in one individual. This 

 bird came from the eleventh egg of the season, July 1; its clutch-mate sister of 

 July 3 was also abnormal in that she bore only 10 rectrices (tail feathers), instead 

 of the normal 12. This latter deficiency is shown in 3 other sisters, or in 4 of a 

 total of 5 females which lived long enough to permit an examination of this portion 

 of the plumage; and it is not without interest and significance to note that the 

 reduction of these rectrices is fjuantitatively expressed, in order, by the numbers: 

 11, 10, 10, 9. And that this series (9 represents primaries not rectrices) runs from 

 early in the season to later in the season, and thus corresi:)onds also to the sliding 

 scale of longevity already noted. Moreover, all of the males and the earliest female 

 of this series have the normal number — 12 tail feathers. 



The third abnormality or group of abnormalities was borne by a bird hatched 

 from the sixteenth egg of the season (August 22) and the second of the clutch. 

 It had much "white" scattered over the body (see footnote to table 15), and there 

 "was nothing in the ancestry to explain these flocks and patches of white." As a 

 further expression of weakness this bird had only 9 primaries. It is probable that 

 the second egg of the following clutch — the very last of the season — produced also 

 a bird with abnormal plumage; its "down" was recorded as "almost whitish," 

 but it died before anything further could be learned of it. 



In several instances we shall again see the same thing that is evident here, 

 namely, that deviations from the type present themselves most frequently in 

 individuals hatched from "weakened" germs. Among the pigeons the factors 

 producing these weakened germs are at least partially known, and a considerable 

 part of the effort of this volume aims at the presentation of this information. 



