If this book should be instrumental, as I confidently trust it will, in destroying some medieval superstitions, in dissipating some hampering and cramping errors, in instilling some hope in the hearts of the hopeless, in bringing a little joy into the homes of the joyless, in increasing in however slight a degree the sum total of human happiness, its mission shall have been gloriously fulfilled. For this is the mission of the book: to increase the sum total of human happiness. W.J.R. 12 Mount Morris Park W., New York City. Jan. 1, 1917. CONTENTS CHAPTER PAGE I. THE PARAMOUNT NEED OF SEX KNOWLEDGE FOR GIRLS AND WOMEN 23 Why Sex Knowledge is of Paramount Importance to Girls and Women--Reasons Why a Misstep in a Girl Has More Serious Consequences than a Misstep in a Boy--The Place Love Occupies in Woman's Life--Woman's Physical Disabilities. II. THE FEMALE SEX ORGANS; THEIR ANATOMY 31 The Internal Sex Organs--The Ovaries--The Fallopian Tubes--The Uterus--The Divisions of the Uterus--Anteversion, Anteflexion, Retroversion, Retroflexion, of the Uterus--Endometritis--The Vagina--The Hymen--Imperforate Hymen--The External Genitals--The Vulva, Labia Majora, Labia Minora, the Mons Veneris, the Clitoris, the Urethra--The Breasts--The Pelvis--The Difference Between the Male and Female Pelvis. III. THE PHYSIOLOGY OF THE FEMALE SEX ORGANS 49 Function of the Ovaries--Internal Secretion of the Ovaries-- Function of the Internal Secretion--Number of Ova in the Ovaries--The Graafian Follicles--Ovulation--Corpora Lutea--Function of the Fallopian Tubes--Function of the Vagina--Functions of the Vulva, Clitoris and Mons Veneris-- Function of the Breasts--Besides Secreting Milk Breast Has Sexual Function--The Orgasm--Pollutions in Women--Secondary Sex Characters--Differences Between Woman and Man. IV. THE SEX INSTINCT 62 Universality of the Sex Instinct--Not Responsible for Our Thoughts and Feelings. V. PUBERTY 65 Physical Changes in Puberty--Physical Changes in the Genital Organs and in the Rest of the Body--Psychic Changes--Puberty and Adolescence--Nubility. VI. MENSTRUATION 71 Definition of Menstruation--Where Menstrual Blood Comes From--Age of Menstruation--Age of Cessation of Menstruation--Duration--Amount--Regularity and Irregularity. VII. ABNORMALITIES OF MENSTRUATION 75 Disorders of Menstruation--Menorrhagia--Metrorrhagia-- Amenorrhea--Vicarious Menstruation--Dysmenorrhea of Organic and of Nervous Origin.