The duration and the intensity of the sexual life of woman depends upon a series of external conditions affecting the individual, but especially upon the inherited predispositions, upon the constitutional conditions, upon the varying vital power of the individual. My own observations have led me to formulate, as a general law, that the earlier a woman (climatic and social conditions being similar in the cases under comparison) arrives at puberty, the earlier, that is to say, that menstruation first makes its appearance, the greater will be the intensity and the longer the duration of sexual activity, the more will the woman in question be predisposed to bear many children, the more powerfully will the sexual impulse manifest itself in her, and the later will the menopause appear. It seems that in such women a more intense vitality animates the reproductive system, bringing about an earlier ripening of ova, a more favorable predisposition on the part of these ova to fertilization by the spermatozoa, a livelier manifestation of sexual sensibility, and a longer duration of ovarian functional activity. My general views on this subject are embodied in the following propositions: 1. The duration of sexual activity is less in the women belonging to the countries of southern Europe than in those belonging to the countries of northern Europe. It would appear that in those climates in which ovulation begins sooner and menstruation first appears at an earlier age, the menopause also appears earlier; but that, on the contrary, in those climates in which puberty is late in its appearance, the decline of sexual activity is similarly postponed. 2. Women in our mid-European climates, in whom puberty appears at an early age, the first menstruation occurring between the ages of thirteen and sixteen, exhibit a more prolonged duration of the sexual life, of menstrual functional activity, than women in whom menstruation begins late, between the ages of seventeen and twenty. Extremely early appearance of the first menstruation—so early as to be altogether abnormal—has, however, the same significance as abnormally late onset of menstruation; both indicate that the sexual life will be of short duration. 3. Women whose reproductive organs have been the seat of a sufficient amount of functional activity, who have had frequent sexual intercourse, have given birth to several children, and have themselves suckled their children, have a sexual life of longer duration, as manifested by the continuance of menstruation, than women whose circumstances have been just the opposite of these, unmarried women, for instance, women early widowed, and barren women. Sexual intercourse at a very early age, however, accelerates the onset of the climacteric period and the termination of the sexual life. The same result follows severe or too frequent confinements.