122 Mendeliau Sex-Factors in Man 



for sex-factors, and that " vnalcness " is dominant to " femaleness." 

 Individuals (zygotes) may therefore be represented as: 



Normal female NN i ? 



Colour-blind female nn^ t 



Heterozygous (apparently normal) female Nn ? ? 



Colour-blind male nn cf ? 

 " Normal " male n i . N ■} 

 (repulsion existing between N and i ) 



The various equations become : 



(a) Normal female x CB male. 



(b) Heterozygous female x " normal " (really heterozygous) male. 

 Nn^ ? x/.J".iV? =i>»^^ +Nn^^ + i\"« ? ? +NN^ ?. 



(c) Heterozygous female x GB male. 



Nni^ X nnj' ? = >m,f ? + NnJ' ? + nn $ $ -f iV/( $ ? . 



(d) CB female x " normal " (really heterozygous) male. 



H«? ? xn^.N^ =nn^% +Nn%%. 



If the above view of the sex-composition of Man be accepted, it of 

 course follows that the sex of offspring is determined, not by the mother, 

 but by the father, in Man. 



{Received 1 Jan. 1913.) 



