655 



see from (lie grapli and from Table III, tlie beginning of the varia- 

 bility-curve lies for both types in the lü'''year; in the "brunettes" 

 this begins at 10 years 5 montiis, in the "blondes" at 10 years 4 

 months; so for both groups what one can designate as the thres- 

 hold-age of sexual maturity, is the same. After this beginning the 

 curve for the fair type mounts more rapidly than for the "brunettes"; 

 the end of the normal variability, however, is the same for both 

 types, and lies in the 18''' year. 



The exact difference between both groups appears from the 

 following average figures, which have again been calculated inclu- 

 ding the months: 



Average age of menarche in "blondes": 13 years, 5 months, 17 

 days; in "brunettes": 14 years, 4 months, 5 days. So this makes 

 a difference of full 10 months bel ween both types. 



A difference of this sort, and in a contrary direction to what I 

 had expected, is very remarliable. As we have to do here with two 

 groups of people living in the same ciicumstances, which excludes 

 external factors which might inflneiice the menarche, this difference 

 must be entirely regarded as the result of an internal factor, and it 

 is only the racial factor which can be taken into consideration here. 



The light-eyed component of our population belongs, in general, to 

 the race which peoples the North of Europe, the "Homo nordicus", 

 while tlie brown-eyed, which constitutes about a third part of the 

 Dulch people, as is proved by a foinier investigation of mine, belongs 

 to the race inhabiting the centre of Europe, the "Homo alpinus". 



It appears, therefore, that a lesser development of the pigment 

 is accompanied by an acceleration of the sexual development. The 

 relation between l)oth phenomena is, however, not so sim|)le; which 

 can be seen from the fact that the average age of the menarche in the 

 more strongly pigmented Jewesses, is earlier than in the "blondes". 



The activation of the sexual sphere of the developing individual is 

 dependent on very many factors; and, in considering the difference 

 which has come to light, we must not forget the possibility that the 

 racial factor which is here at work, could be of a psychological 

 instead of a physiological nature. The blonde as well as the brunette 

 girl has reached the threshold-age of maturity on arriving at the 

 age of 10-and-a-half years. (Later on it will appear that this also 

 holds good for the Jewish girl). The time which passes for each 

 individual betw^een this age and the activation of the sexual functions, 

 is determined by a number of external and internal factors, and 

 among the latter we leave room for the special psyche of each race. 



Thus far on the average age of the menarche in the Dutch 



