HUMAN FECUNDITY 91 



about the age at which it ends. There are at least three factors 

 which influence the age at which menstruation begins — climate, 

 race, and general nature of the surrounding conditions. 



Generally speaking, the hotter the climate the earlier menstrua- 

 tion begins. Englemann gives the following figures : ^ 



Zone. Average Age for Menstruation. 

 Tropics ... 12-9 j^ears 



Temperate . . 15-5 ,, 



Cold ... 16-5 „ 



and Krieger gives the following figures : ^ 



Place. 

 Christiania 

 Berlin 

 London 

 Lyons 

 Marseilles 

 Calcutta 

 Sierra Leone 



It further appears that there is a tendency for menstruation 

 to end earlier in hot climates ; so much so that upon the whole 

 the mature period is shorter in hot than in cold climates. 



There is, however, no very close or definite connexion between 

 chmate and menstruation. In the United States it has not been 

 found possible to detect any influence of climate upon menstrua- 

 tion, though this country stretches from 29° to 45° of latitude, 

 and has a temperature the annual average of which varies 

 from 40° F. to 70° F. But if the conditions concerning 

 the different racial elements in the population of the country are 

 examined, it is found that in whatever part of the country they 

 may be the average age for each racial element remains constant, 

 and usually varies slightly from the average age for the whole 

 population.^ There are other indications that the age at which 

 menstruation begins are connected with differences in race. 

 Krieger quotes the following from Joachim for girls in Hungary : ^ 



Mace. Average Age of Menstruation. 



Slavonic . . . 16 to 17 years 



Magyar ... 15 ,, 16 ,, 



Jewish . . . 14 „ 15 ,, 



Styrian ... 13 „ 14 „ 



* Engelmann, Trans. Amer. Oyn. Soc., vol. xxvi, p. 87. - Krieger, Die 



Menstruation, p. 52. See also Ploss and Bartels, Das Weib, vol. i, p. 421. 

 * Engelmann, loc. cit., p. 98. * Krieger, loc. cit., p. 17. 



