The following account is given by _Havelock Ellis_ of the differential characters of the sexual impulse in the female: “In courtship, woman plays a more passive part than man; in woman the physiological mechanism of the sexual processes is more complicated, and the orgasm develops more deliberately; the sexual impulse in woman needs more frequently to be actively stimulated; the culmination of sexual activity is attained later in the life of woman than in the life of man, the strength of sexual desire in woman becomes greater after she has entered upon regular sexual intercourse, women bear sexual excesses better than men; the sexual sphere is larger and more widely diffused in women than it is in men; finally, in woman the sexual impulse exhibits a distinct tendency to periodic exacerbations, and it is in any case much more variable than in man.” The same author, who has published several notable biological studies on subjects connected with sex, maintains that the source of erotic pleasure in the case of the male lies in activity, but in the female in the passive state, in the experience of compulsion, and he holds that sexual subordination is a necessary element in the sexual enjoyment of women. _Hegar_ maintains that under the term _sexual impulse_ two distinct conceptions are confounded: First, the impulse toward copulation, the desire of carnal union with a member of the opposite sex; secondly, the impulse toward reproduction, the desire for children. At the same time, this author admits that it is questionable if we can properly speak of an impulse toward reproduction, when reproduction is merely a consequence of copulation; in the case of civilized man, at any rate, so much reflection is connected with the idea of reproduction that it can hardly be proper to speak of anything of the nature of an impulse. In the case of woman, the expression is less unsuitable, since in woman special organs exist for the maintenance of the ovum after fertilization, and these organs may perhaps lead to the production of this peculiar form of mental activity. According to _Darwin_, a comparatively less intensity of sexual desire is common to the females of all species of the animal kingdom. The female demands a prolonged courtship, and often endeavors for a considerable time to elude the male. In the lowest classes of the animal kingdom the female leads a separate existence as soon as she has been fertilized by the male, the sexual functions being thus subordinated to the maternal. Among birds at the pairing season the male is always the more passionate and active of the two, whilst the female commonly remains passive and occupies herself in building the nest. Among mammals, it is difficult to determine whether sexual feeling is stronger in the female or in the male; but it is certain that sexual relations are seldom long lasting, they continue in most cases only during the period of heat or rut, and at most only till the birth of the young.