concerning the truth of which it is possible to dispute; it is a self-evident fact. The difficulty is not as to its existence, but as to the methods by which it may be most precisely measured. It is fundamentally a psychological process, and should be approached from the psychological side. This is the reason for dealing with it here. Obscure as the psychological aspects of sexual selection still remain, they are full of fascination, for they reveal to us the more intimate sides of human evolution, of the process whereby man is molded into the shapes we know. HAVELOCK ELLIS. Carbis Water, Lelant, Cornwall, England. CONTENTS. SEXUAL SELECTION IN MAN. The External Sensory Stimuli Affecting Selection in Man. The Four Senses Involved. TOUCH. I. The Primitive Character of the Skin. Its Qualities. Touch the Earliest Source of Sensory Pleasure. The Characteristics of Touch. As the Alpha and Omega of Affection. The Sexual Organs a Special Adaptation of Touch. Sexual Attraction as Originated by Touch. Sexual Hyperæsthesia to Touch. The Sexual Associations of Acne. II. Ticklishness. Its Origin and Significance. The Psychology of Tickling. Laughter. Laughter as a Kind of Detumescence. The Sexual Relationships of Itching. The Pleasure of Tickling. Its Decrease with Age and Sexual Activity. III. The Secondary Sexual Skin Centres. Orificial Contacts. Cunnilingus and Fellatio. The Kiss. The Nipples. The Sympathy of the Breasts with the Primary Sexual Centres. This Connection Operative both through the Nerves and through the Blood. The Influence of Lactation on the Sexual Centres. Suckling and Sexual Emotion. The Significance of the Association between Suckling and Sexual Emotion. The Association as a Cause of Sexual Perversity. IV. The Bath. Antagonism of Primitive Christianity to the Cult of the Skin. Its Cult of Personal Filth. The Reasons which Justified this Attitude. The World-wide Tendency to Association between Extreme Cleanliness and Sexual Licentiousness. The Immorality Associated with Public Baths in Europe down to Modern Times. V. Summary. Fundamental Importance of Touch. The Skin the Mother of All the Other Senses. SMELL. I. The Primitiveness of Smell. The Anatomical Seat of the Olfactory Centres. Predominance of Smell among the Lower Mammals. Its Diminished Importance in Man. The Attention Paid to Odors by Savages. II. Rise of the Study of Olfaction. Cloquet. Zwaardemaker. The Theory of Smell. The Classification of Odors. The Special Characteristics of Olfactory Sensation in Man. Smell as the Sense of Imagination. Odors as Nervous Stimulants. Vasomotor and Muscular Effects. Odorous Substances as Drugs. III.