Detumescence—­Ejaculation—­The Virile Reflex—­The General Phenomena of
Detumescence—­The Circulatory and Respiratory Phenomena—­Blood
Pressure—­Cardiac Disturbance—­Glandular Activity—­Distillatio—­The
Essentially Motor Character of Detumescence—­Involuntary Muscular
Irradiation to Bladder, etc.—­Erotic Intoxication—­Analogy of Sexual
Detumescence and Vesical Tension—­The Specifically Sexual Movements of
Detumescence in Man—­In Woman—­The Spontaneous Movements of the Genital
Canal in Woman—­Their Function in Conception—­Part Played by Active
Movement of the Spermatozoa—­The Artificial Injection of Semen—­The Facial
Expression During Detumescence—­The Expression of Joy—­The Occasional
Serious Effects of Coitus.

We have seen what the object of detumescence is, and we have briefly considered the organs and structures which are chiefly concerned in the process.  We have now to inquire what are the actual phenomena which take place during the act of detumescence.

Detumescence is normally linked closely to tumescence.  Tumescence is the piling on of the fuel; detumescence is the leaping out of the devouring flame whence is lighted the torch of life to be handed on from generation to generation.  The whole process is double and yet single; it is exactly analogous to that by which a pile is driven into the earth by the raising and then the letting go of a heavy weight which falls on to the head of the pile.  In tumescence the organism is slowly wound up and force accumulated; in the act of detumescence the accumulated force is let go and by its liberation the sperm-bearing instrument is driven home.  Courtship, as we commonly term the process of tumescence which takes place when a woman is first sexually approached by a man, is usually a highly prolonged process.  But it is always necessary to remember that every repetition of the act of coitus, to be normally and effectively carried out on both sides, demands a similar double process; detumescence must be preceded by an abbreviated courtship.

This abbreviated courtship by which tumescence is secured or heightened in the repetition of acts of coitus which have become familiar, is mainly tactile.[98] Since the part of the man in coitus is more active and that of the woman more passive, the sexual sensitivity of the skin seems to be more pronounced in women.  There are, moreover, regions of the surface of a woman’s body where contact, when sympathetic, seems specially liable to arouse erotic excitement.  Such erogenous zones are often specially marked in the breasts, occasionally in the palm of the hand, the nape of the neck, the lobule of the ear, the little finger; there is, indeed, perhaps no part of the surface of the body which may not, in some individuals at some time, become normally an erogenous zone.  In hysteria the erotic excitability of these zones is sometimes very intense.  The lips are, however, without doubt, the most persistently and poignantly sensitive region of the whole body outside the sphere of the sexual organs themselves.  Hence the significance of the kiss as a preliminary of detumescence.[99]