28 STATISTICS OF SEX 



9. SUMMARY OF CONCLUSIONS. 



I do not present the following summary of conclusions as being, in 

 all cases, so well established as not to be worthy of farther investigation. 

 \Yhether well or ill established, they are those indicated by the statis- 

 tics, and I earnestly hope that other investigators, more especially con- 

 cerned with the subject, will take it up with more extended data and 

 test each conclusion separately. With this proviso we may say that the 

 following propositions are indicated by the statistics with a greater or 

 less degree of probability. 



I. The preponderance of male over female births probably varies with 

 the race. Although remarkably uniform in all branches of the Semitic 

 race, it seems to be either non-existent or quite small in the Negro race. 



II. There are no important differences as regards capacity for pro- 

 ducing 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. In view of the great variety of conditions on which this con- 

 clusion is based, it seems in the highest degree unlikely that there is 

 any way by which a parent can affect the s^ex of his or her offspring. 



III. 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 classifi- 

 cation of the sex of third born and following children according to the 

 age of the father. 



IV. 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, 

 but throw no light upon the question of the time which they occupy. 



V. 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 preponder- 

 ance in the case of the second child. But there is no conclusive evi- 

 dence that, after a mother lias had two children, there is any change 

 in her tendencies. 



VI. 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. 



