[174] Camerer found that from September to November is the period of greatest metabolic activity. [175] Haig, _Uric Acid_, 6th edition, 1903, p. 33. AUTO-EROTISM: A STUDY OF THE SPONTANEOUS MANIFESTATIONS OF THE SEXUAL IMPULSE. I. Definition of Auto-erotism--Masturbation only Covers a Small Portion of the Auto-erotic Field--The Importance of this Study, especially To-day--Auto-erotic Phenomena in Animals--Among Savage and Barbaric Races--The Japanese _rin-no-tama_ and other Special Instruments for Obtaining Auto-erotic Gratification--Abuse of the Ordinary Implements and Objects of Daily Life--The Frequency of Hair-pin in the Bladder--The Influence of Horse-exercise and Railway Traveling--The Sewing-machine and the Bicycle--Spontaneous Passive Sexual Excitement--_Delectatio Morosa_--Day-dreaming--_Pollutio_--Sexual Excitement During Sleep--Erotic Dreams--The Analogy of Nocturnal Enuresis--Differences in the Erotic Dreams of Men and Women--The Auto-erotic Phenomena of Sleep in the Hysterical--Their Frequently Painful Character. By "auto-erotism" I mean the phenomena of spontaneous sexual emotion generated in the absence of an external stimulus proceeding, directly or indirectly, from another person. In a wide sense, which cannot be wholly ignored here, auto-erotism may be said to include those transformations of repressed sexual activity which are a factor of some morbid conditions as well as of the normal manifestation of art and poetry, and, indeed, more or less color the whole of life. Such a definition excludes the normal sexual excitement aroused by the presence of a beloved person of the opposite sex; it also excludes the perverted sexuality associated with an attraction to a person of the same sex; it further excludes the manifold forms of erotic fetichism, in which the normal focus of sexual attraction is displaced, and voluptuous emotions are only aroused by some object--hair, shoes, garments, etc.--which, to the ordinary lover, are of subordinate--though still, indeed, considerable--importance.[176] The auto-erotic field remains extensive; it ranges from occasional voluptuous day-dreams, in which the subject is entirely passive, to the perpetual unashamed efforts at sexual self-manipulation witnessed among the insane. It also includes, though chiefly as curiosities, those cases in which individuals fall in love with themselves. Among auto-erotic phenomena, or on the borderland, we must further include those religious sexual manifestations for an ideal object, of which we may find evidence in the lives of saints and ecstatics.[177] The typical form of auto-erotism is the occurrence of the sexual orgasm during sleep.