. The physical basis of heredity . Fig. 69.—Cross between white-eyed male and a red-eyed female of the vinegar fly. SEX-CHROMOSOMES AND INHERITANCE 169. Fia. 70.—Cross between white-eyed female and a red-eyed male of the vinegar fly. 170 PHYSICAL BASIS OF HEREDITY are bred together, the results are as follows: Half thedaughters have white eyes (ww), half red eyes (wW);half the sons have white eyes (w), half red eyes (TF). Itwill be seen that the red-eyed Fg daughters are all hetero-zygous, and should give 50 per cent, white and 50 per cent,red offspring if mated to white-eyed males. This occur
. The physical basis of heredity . Fig. 69.—Cross between white-eyed male and a red-eyed female of the vinegar fly. SEX-CHROMOSOMES AND INHERITANCE 169. Fia. 70.—Cross between white-eyed female and a red-eyed male of the vinegar fly. 170 PHYSICAL BASIS OF HEREDITY are bred together, the results are as follows: Half thedaughters have white eyes (ww), half red eyes (wW);half the sons have white eyes (w), half red eyes (TF). Itwill be seen that the red-eyed Fg daughters are all hetero-zygous, and should give 50 per cent, white and 50 per cent,red offspring if mated to white-eyed males. This occurs. Similar illustrations might be given for any of the50 sex-linked characters of Drosophila. Of these the sex-linked lethals form the most interesting cases and will bespoken of in another connection. Despite the fact that the results in one of the two fore-going crosses gave a 3; 1 ratio, and in its reciprocal a 1:1ratio, the results in both cases confoiTU to Mendels firstlaw of segregation. The peculiarity of the 1:1 ratio isdue to the fact that the P^ red-eyed male is in a senseheterozygous for the wild-type eye color (since he hasbut one X
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectheredit, bookyear1919
