II
The Object of Detumescence—Erogenous Zones—The Lips—The Vascular Characters of Detumescence—Erectile Tissue—Erection in Woman—Mucous Emission in Women—Sexual Connection—The Human Mode of Intercourse—Normal Variations—The Motor Characters of 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]]
The importance of the lips as a normal erogenous zone is shown by the experiments of Gualino. He applied a thread, folded on itself several times, to the lips, thus stimulating them in a simple mechanical manner. Of 20 women, between the ages of 18 and 35, only 8 felt this as a merely mechanical operation, 4 felt a vaguely erotic element in the proceeding, 3 experienced a desire for coitus and in 5 there was actual sexual excitement with emission of mucus. Of 25 men, between the ages of 20 and 30, in 15 all sexual feeling was absent, in 7 erotic ideas were suggested with congestion of the sexual organs without erection, and in 3 there was the beginning of erection. It should be added that both the women and the men in whom this sexual reflex was more especially marked were of somewhat nervous temperament; in such persons erotic reactions of all kinds generally occur most easily. (Gualino, "Il Rifflesso Sessuale nell' eccitamento alle labbre," Archivio di Psichiatria, 1904, p. 341.)
As tumescence, under the influence of sensory stimulation, proceeds toward the climax when it gives place to detumescence, the physical phenomena become more and more acutely localized in the sexual organs. The process which was at first predominantly nervous and psychic now becomes more prominently vascular. The ancient sexual relationship of the skin asserts itself; there is marked surface congestion showing itself in various ways. The face tends to become red, and exactly the same phenomenon is taking place in the genital organs; "an erection," it has been said, "is a blushing of the penis." The difference is that in the genital organs this heightened vascularity has a definite and specific function to accomplish—the erection of the male organ which fits it to enter the female parts—and that consequently there has been developed in the penis that special kind of vascular mechanism, consisting of veins in connective tissue with unstriped muscular fibers, termed erectile tissue.[[100]]
It is not only the man who is supplied with erectile tissue which in the process of tumescence becomes congested and swollen. The woman also, in the corresponding external genital region, is likewise supplied with erectile tissue now also charged with blood, and exhibits the same changes as have taken place in her partner, though less conspicuously visible. In the anthropoid apes, as the gorilla, the large clitoris and the nymphæ become prominent in sexual excitement, but the less development of the clitoris in women, together with the specifically human evolution of the mons veneris and larger lips, renders this sexual turgescence practically invisible, though it is perceptible to touch in an increased degree of spongy and elastic tension. The whole feminine genital canal, including the uterus, indeed, is richly supplied with blood-vessels, and is capable during sexual excitement of a very high degree of turgescence, a kind of erection.
The process of erection in woman is accompanied by the pouring out of fluid which copiously bathes all parts of the vulva around the entrance to the vagina. This is a bland, more or less odorless mucus which, under ordinary circumstances, slowly and imperceptibly suffuses the parts. When, however, the entrance to the vagina is exposed and extended, as during a gynæcological examination which occasionally produces sexual excitement, there may be seen a real ejaculation of the fluid which, as usually described, comes largely from the glands of Bartholin, situated at the mouth of the vagina. Under these circumstances it is sometimes described as being emitted in a jet which is thrown to a distance.[[101]] This mucous ejaculation was in former days regarded as analogous to the seminal ejaculation in man, and hence essential to conception. Although this belief was erroneous the fluid poured out in this manner whenever a high degree of tumescence is attained, and before the onset of detumescence, certainly performs an important function in lubricating the entrance to the genital canal and so facilitating the intromission of the male organ.[[102]] Menstruation has a similar influence in facilitating coitus, as Schurig long since pointed out.[[103]] A like process takes place during parturition when the same parts are being lubricated and stretched in preparation for the protrusion of the fœtal head. The occurrence of the mucous flow in tumescence always indicates that that process is actively affecting the central sexual organs, and that voluptuous emotions are present.[[104]]