Definition of Instinct--The Sexual Impulse a Factor of the Sexual
Instinct--Theory of the Sexual Impulse as an Impulse of Evacuation--The
Evidence in Support of this Theory Inadequate--The Sexual Impulse to Some
Extent Independent of the Sexual Glands--The Sexual Impulse in Castrated
Animals and Men--The Sexual Impulse in Castrated Women, After the
Menopause, and in the Congenital Absence of the Sexual Glands--The
Internal Secretions--Analogy between the Sexual Relationship and that of
the Suckling Mother and her Child--The Theory of the Sexual Impulse as a
Reproductive Impulse--This Theory Untenable--Moll's Definition--The
Impulse of Detumescence--The Impulse of Contrectation--Modification of
this Theory Proposed--Its Relation to Darwin's Sexual Selection--The
Essential Element in Darwin's Conception--Summary of the History of the
Doctrine of Sexual Selection. Its Psychological Aspect--Sexual Selection a
Part of Natural Selection--The Fundamental Importance of
Tumescence--Illustrated by the Phenomena of Courtship in Animals and in
Man--The Object of Courtship is to Produce Sexual Tumescence--The
Primitive Significance of Dancing in Animals and Man--Dancing is a Potent
Agent for Producing Tumescence--The Element of Truth in the Comparison of
the Sexual Impulse with an Evacuation, Especially of the Bladder--Both
Essentially Involve Nervous Explosions--Their Intimate and Sometimes
Vicarious Relationships--Analogy between Coitus and Epilepsy--Analogy of
the Sexual Impulse to Hunger--Final Object of the Impulses of Tumescence
and Detumescence.