┌───────────┬────────┬────────┬─────────┬──────────┬─────────┬───────┬───────┐ │ │Germany.│Austria.│ France. │ England. │Denmark. │Norway.│Russia.│ ├───────────┼────────┼────────┼─────────┼──────────┼─────────┼───────┼───────┤ │Number of │ │ │ │ │ │ │ │ │ Cases │ 722 │ 265 │ 178 │ 500 │ 312 │ 391 │ 100 │ ├───────────┼────────┼────────┼─────────┼──────────┼─────────┼───────┼───────┤ │Mean │ │ │ │ │ │ │ │ │ duration │ │ │ │ │ │ │ │ │ of │ │ │ │ │ │ │ │ │ menstrual│ │ │ │ │ │ │ │ │ activity,│ │ │ │ │ │ │ │ │ in years │ 30.4 │ 29.1 │ 29.1 │ 31.8 │ 27.9 │ 32 │ 31 │ ├───────────┼────────┼────────┼─────────┼──────────┼─────────┼───────┼───────┤ │Observers’ │Krieger,│ │ Brierre │ │ │ │ │ │ names │ L. │ │ de │ │ │Faye & │ │ │ │ Mayer. │Szukits.│Boismont.│Whitehead.│Hannover.│ Vogt. │Lieven.│ └───────────┴────────┴────────┴─────────┴──────────┴─────────┴───────┴───────┘ In the temperate zone the sexual life of woman lasts longer than in the colder and subarctic regions. Still more favorable is the contrast between the temperate zone and the countries of the tropics, in which the duration of the period of menstrual activity is limited to eighteen or twenty years. According to some isolated observations the duration of sexual activity in Arabian women in Africa was as little as nine years. A certain influence on the duration of the sexual life is exercised by the commencement of menstruation at an earlier or later age than the average. The total duration of menstrual activity is more variable in women who begin to menstruate early than in women who begin to menstruate late, in whom the duration of the sexual life is a more regular one. In those women who begin to menstruate early the mean duration of the sexual life is about thirty-three years, in those who begin to menstruate late it is about twenty-seven years. The following data, based on the observation of 250 cases, are published by _W. Guy_, regarding the duration of the sexual life, that is to say of menstrual activity, in women beginning to menstruate early and those beginning to menstruate late, respectively: