. Contributions to the genetics of Drosophila melanogaster. Drosophila melanogaster; Heredity; Karyokinesis. 260' THE SECOND-CHROMOSOME GROUP examining the character of the Fi flies, and it was not until the F2 began to hatch that it was reahzed that the other alternative was correct—that "star," as the character was called, was an auto- somal dominant. Two of the Fi pairs gave in F2 no star whatever (1627, 1629), while a third pair (1628, table 108) gave stars among both males and females to the extent of half the flies (52 per cent). The fact that half the flies were stars showed t
. Contributions to the genetics of Drosophila melanogaster. Drosophila melanogaster; Heredity; Karyokinesis. 260' THE SECOND-CHROMOSOME GROUP examining the character of the Fi flies, and it was not until the F2 began to hatch that it was reahzed that the other alternative was correct—that "star," as the character was called, was an auto- somal dominant. Two of the Fi pairs gave in F2 no star whatever (1627, 1629), while a third pair (1628, table 108) gave stars among both males and females to the extent of half the flies (52 per cent). The fact that half the flies were stars showed that this culture came from a heterozygous dominant and a wild- type Fi pair. That star was an autosomal dom- inant was proved by the sister cultures which gave no stars; had star been sex-linked all the Fi females would have been star and hence every Fo pair should have given results like those of culture 1628. These facts were confirmed by the results of further tests of star males; for star males out- crossed to wild females gave in Fi stars to the extent of half the flies (table 109, 337 stars in a total of 683, or per cent), and the stars were evenly distributed among the males and females. Had star been sex- linked, none of the males but all of the females should have been star. Table 108.—Pi, star cf X wild 9 ; Fi pair (Fi flies chosen at random).. Text-figure 83.—Star eye, showing the arrangement of the facets and hairs. Com- pare with the normal con- dition shown in plate 10, figure 3c. Mar. 12, 1915. Wild- type 9. Star 9. Wild- type cf. Star cf. 1628 44 39 33 45 Table 109.—Pi, star d' X wild 9. Mar. 27, 1915. Wild- type 9. Wild- type cf. Star 9 . star cf. 1719 129 136 129 115 1914 1915 28 27 26 24 32 37 1916 346 337 LETHAL NATURE OF THE HOMOZYGOUS STAR. At the same time that the male out-crossed tests were made, a few pairs of star female by star male were mated. In the next generation, which corresponded to an F2, the flies in one culture (1739,
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