. Readings in evolution, genetics, and eugenics. Evolution; Heredity; Eugenics. 434 READINGS IN EVOLUTION, GENETICS, AND EUGENICS only in male individuals. But if the recessive sex-linked character is introduced by the female parent, it appears in Fi in male individuals but in Fj in both sexes. Suppose now a cross is made between two races, each of which possesses a different sex-linked recessive character, as for example white eye and yeUow body. (See Table II, p. 436.) If the white-eyed Flies Chromosomes. Parents X M 6^ 9 X n Gametes Fi Gairieles XX JK X© m Fz Fig. 87.—Sex-linked inheritance
. Readings in evolution, genetics, and eugenics. Evolution; Heredity; Eugenics. 434 READINGS IN EVOLUTION, GENETICS, AND EUGENICS only in male individuals. But if the recessive sex-linked character is introduced by the female parent, it appears in Fi in male individuals but in Fj in both sexes. Suppose now a cross is made between two races, each of which possesses a different sex-linked recessive character, as for example white eye and yeUow body. (See Table II, p. 436.) If the white-eyed Flies Chromosomes. Parents X M 6^ 9 X n Gametes Fi Gairieles XX JK X© m Fz Fig. 87.—Sex-linked inheritance of white and red eyes in Drosophila. Parents white-eyed male and red-eyed female; Fi, red-eyed males and females; Fj, red- eyed females and equal nvmibers of red-eyed and white-eyed males. A black X indicates an X chromosome bearing the gene for red eye, a white X bears white eye. nj indicates that X is wanting; in recent publications Morgan replaces it by F. (From Conklin, after Morgan.) parent is a female, there will be produced white-eyed males in Fi and white-eyed flies of both sexes in Fj. But the male parent being yellow, there wiU be no yellow flies produced in F, and only yellow males in F2. In the reciprocal cross (yellow femaleX white-eyed male) yellow males will be produced in F, and yellow flies of both sexes in Fj, while white-eyed flies will not appear until Fj and then only in the male sex. In either of the reciprocal crosses we expect the pro- duction in Fj both of yellow-bodied males and of white-eyed Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Newman, Horatio Hackett, b. 1875. Chicago : University of Chicago Press
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