Hormones and heredity; a discussion of the evolution of adaptations and the evolution of species; . he defect wasintroduced by the normal sighted mother also, carried by her as a recessive. The fact thatunaffected males do not transmit the defect shows,according to Bateson, that it is due to the additionof a factor to the normal, not to omission of a to later researches as quoted byDoncaster, colour-blindness is due to the loss of somefactor which is present in the normal normal male is heterozygous for this normalfactor. If we denote the presence of the
Hormones and heredity; a discussion of the evolution of adaptations and the evolution of species; . he defect wasintroduced by the normal sighted mother also, carried by her as a recessive. The fact thatunaffected males do not transmit the defect shows,according to Bateson, that it is due to the additionof a factor to the normal, not to omission of a to later researches as quoted byDoncaster, colour-blindness is due to the loss of somefactor which is present in the normal normal male is heterozygous for this normalfactor. If we denote the presence of the normal * Determination of Sex, Camb. Univ. Press, MendeVs Principles of Heredity, 1909. SEX-CHARACTERS IN EVOLUTION 111 factor by N and its absence or recessive by n, then themale is Nn, while the female is homozygous or NN,But in addition to this it is the male in this casewhich is heterozygous for sex, and n goes to themale-producing sperms, N to the in the mating of normal man witli normalwoman the transmission is as follows:— Gdmefes n 6 Nn 6 X NN 9/V 9 X ^/K. f^n 6 A//V<^ That is all offspring normal, but the males againheterozygous. An affected male has the constitution nn, and if hemarries a normal woman the descent is as follows :— nnd X NN(^Gametes n^6 -¥ no x N + A/
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Keywords: ., bookcentury1900, bookdecade1920, bookpublisherlondo, bookyear1921
