Bridges' Genie Balance Theory of Sex Determination


IN Bridges' table of sex indices,1 in connexion with balanced intersexuality in Drosophila, the fact that the female intersex is a triplo IV and the male intersex a diplo IV is not expressed. The chromosomal difference between the two is not allowed for in the calculation of the series of sex indices. Since the addition of a IV chromosome to the male intersex chromosome relation converts it into a female intersex, the “IV chromosome must have a net female tendency similar to that of the X and different from that of the other autosomes”. The following modification is, therefore, suggested: X and IV represent the totality of female determining genes. II and III represent the totality of male determining genes.

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  1. 1

    Bridges, C. B., Amer. Nat., 59, 127; 1925.

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ZWARENSTEIN, H. Bridges' Genie Balance Theory of Sex Determination. Nature 127, 927 (1931).

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