STATISTICAL INVESTIGATION 503 



producing children of one sex rather than the other which are 

 permanent in the individual. All fathers and all mothers are 

 equally likely to have children of either sex, except for the 

 slight variations that may be due to age. 



(2) It seems in the highest degree unlikely that there is any 

 way by which a parent can affect the sex of his or her offspring. 



(3) The most natural inference from all the statistical data 

 is that the functions of the father in generation are entirely 

 asexual, the sex being determined wholly by the mother. If 

 so, it cannot be said that one father is more likely than another 

 to have children of either sex. This conclusion requires to be 

 tested by making a classification of the sex of third-born and 

 following children according to the age of the father. 



(4) The sex is not absolutely determined at any one moment 

 or by any one act, but is the product of a series of accidental 

 causes, some acting in one direction and some in another, until 

 a preponderance in one direction finally determines it. The 

 statistics of twins and triplets seem to show very strongly that 

 these accidents occur after conception. 



(5) The first-born child of any mother is more likely to be 

 a male in the proportion of about 8 to 7. There is probably 

 a smaller preponderance in the case of the second child. But 

 there is no conclusive evidence that, after a mother has had two 

 children, there is any change in her tendencies. 



(6) The observed preponderance of male births in the Semitic 

 race is due mainly to the unisexual tendency of the mother in 

 the case of a first child. 



§ 7. Inconclusive Conclusions. 



At present, it does not seem safe to go further than Morgan 

 does when he says : " In all species with separate sexes the 

 potentiality of producing both sexes is present in all eggs and 



