SCOPE OF GENETICS 37 



male, half female. But I called your attention 

 to the fact that equality of types results when 

 one parent was cross-bred in the character 

 concerned, having received one dose only of 

 the factor on which it depends. So we may 

 feel fairly sure that the distinction between 

 the sexes depends on the presence in one 

 or other of them of an unpaired factor. 

 This conclusion appears to me to follow 

 so immediately on all that we have learnt of 

 genetic physiology that w ith every confidence 

 we may accept it as representing the actual 

 fact. 



The (question which of the two sexes 

 contains the unpaired factor is less easy to 

 answer, but there are several converging lines 

 of evidence which point to the deduction that 

 in Vertebrates at least, and in some other 

 types, it is the female, and I feel little doubt 

 that we shall succeed in proving that in them 

 femaleness is a definite Mendelian factor 



