The culmination of the act of sexual intercourse is called the orgasm. It is the moment at which the pleasurable sensation is at its highest point, the body experiences a thrill, there is a spasmodic contraction in the genital organs, and there is a secretion of fluid from the genital glands and mucous membranes. This fluid in women is not a vital fluid like the semen in man; it is merely mucus, and in some women it is very slight in amount or altogether absent. Adult women who live without sexual relations occasionally have sexual or erotic dreams; that is, they dream that they are in the company of men, playing or having relations with them. Such dreams are usually accompanied by an orgasm or an orgastic feeling, and by a discharge of mucus, the same as in sexual intercourse. Such a discharge of mucus during sleep is called an emission or pollution. In the male sex pollutions play an important role (see the author's "Sex Knowledge for men"), because the semen is a vital fluid, and if it is lost too frequently the system is put under a heavy drain. In boys and men the pollutions or night losses may occur several times a week or even every night, or several times a night. When they occur with such frequency the man may become a wreck. Not so with women. First, pollutions or night dreams in women are much more rare than they are in men; and second, as just mentioned, the fluid secreted by woman during intercourse or during an erotic dream is not of a vital character, as the semen is in man; it is mucus, and the secretion of a mucous fluid, even if somewhat excessive, does not constitute a drain on the system. For this reason women can stand frequently repeated sex relations and emissions or pollutions much better than men can. SUBCHAPTER D THE SECONDARY SEX CHARACTERS The sex organs constitute the primary sex characters. It is they that distinguish primarily one sex from another. But there are numerous other sex characters or sex differences which while not so important serve to differentiate the sexes, at the same time forming points of attraction between one sex and another. For instance, the beard and mustache are a distinct male characteristic and constitute one of the secondary male sex characters. The secondary sex characters are very numerous; one might say that each one of the billions of cells in the body bears the impress of the sex to which it belongs.