42 THE METHODS AND 



The particular interpretation may be im- 

 perfect and even partially wrong ; but that we 

 are at last able to form a working idea of the 

 course of such phenomena at all is a most 

 encouraging fact. If we are right, as I am 

 strongly inclined to believe, we get a glimpse 

 of the significance of the popular idea that in 

 certain respects daughters are apt to resemble 

 their fathers and sons their mothers ; a phe- 

 nomenon which is certainly sometimes to be 

 observed. 



There are several collateral indications 

 that we are on the right track in our theory 

 of the nature of sex. One of these, derived 

 from the peculiar inheritance of colour- 

 blindness, is especially interesting. That 

 affection is common in men, rare in women. 

 Men who are colour-blind can transmit the 

 affection but men who have normal vision 

 cannot. Women however who are ostensibly 

 normal may have colour-blind sons; and 



