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. 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.

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, .)

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.

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 nymphae 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 gynaecological 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. 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. Menstruation has a similar influence in facilitating coitus, as Schurig long since pointed out. A like process takes place during parturition when the same parts are being lubricated and stretched in preparation for the protrusion of the foetal 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.

The secretions of the genital canal and outlet in women are somewhat numerous. We have the odoriferous glands of sebaceous origin, and with them the prepuce of the clitoris which has been described as a kind of gigantic sebaceous follicle with the clitoris occupying its interior. (Hyrtl.) There is the secretion from the glands of Bartholin. There is again the vaginal secretion, opaque and albuminous, which appears to be alkaline when secreted, but becomes acid under the decomposing influence of bacteria, which are, however, harmless and not pathogenic. (Gow, Obstetrical Society of London, January 3, 1894.) There is, finally, the mucous uterine secretion, which is alkaline, and, being poured out during orgasm, is believed to protect the spermatozoa from destruction by the acid vaginal secretion.

The belief that the mucus poured out in women during sexual excitement is feminine semen and therefore essential to conception had many remarkable consequences and was widespread until the seventeenth century. Thus, in the chapter “De Modo coeundi et de regimine eorum qui coeunt” of De Secretis Mulierum, there is insistence on the importance of the proper mixture of the male semen with the female semen and of arranging that it shall not escape from the vagina. The woman must lie quiet for several hours at least, not rising even to urinate, and when she gets up, be very temperate in eating and drinking, and not run or jump, pretending that she has a headache. It was the belief in feminine semen which led some theologians to lay down that a woman might masturbate if she had not experienced orgasm in coitus. Schurig in his Muliebria (1729, pp. 159, et seq.) discusses the opinions of old authors regarding the nature, source, and uses of the female genital secretions, and quotes authorities against the old view that it was female semen. In a subsequent work (Syllepsilogia, 1731, pp. 3, et seq.) he returns to the same question, quotes authors who accept a feminine semen, shows that Harvey denied it any significance, and himself decides against it. It has not seriously been brought forward since.

When erection is completed in both the man and the woman the conditions necessary for conjugation have at last been fulfilled. In all animals, even those most nearly allied to man, coitus is effected by the male approaching the female posteriorly. In man the normal method of male approach is anteriorly, face to face. Leonardo da Vinci, in a well-known drawing representing a sagittal section of a man and a woman connected in this position of so-called Venus obversa; has shown how well adapted the position is to the normal position of the organs in the human species.

Among monkeys, it is stated, congress is sometimes performed when the female is on all fours; at other times the male brings the female between his thighs when he is sitting, holding her with his forepaws. Froriep informed Lawrence that the male sometimes supported his feet on the female’s calves. (Sir W. Lawrence, Lectures on Physiology, 1823, .) A summary of the methods of congress practiced by the various animals below mammals will be found in the article “Copulation” by H. de Varigny in Richet’s Dictionnaire de Physiologie, vol. iv.

The anterior position in coitus, with the female partner lying supine, is so widespread throughout the world that it may fairly be termed the most typically human attitude in sexual congress. It is found represented in Egyptian graves at Benihassan, belonging to the Twelfth Dynasty; it is regarded by Mohammedans as the normal position, although other positions are permitted by the Prophet: “Your wives are your tillage: go in unto your tillage in what manner soever you will;” it is that adopted in Malacca; it appears, from Peruvian antiquities, to have been the position generally, though not exclusively, adopted in ancient Peru; it is found in many parts of Africa, and seems also to have been the most usual position among the American aborigines.

Various modifications of this position are, however, found. Thus, in some parts of the world, as among the Suahelis in Zanzibar, the male partner adopts the supine position. In Loango, according to Pechuel-Loesche, coitus is performed lying on the side. Sometimes, as on the west coast of Africa, the woman is supine and the man more or less erect; or, as among the Queenslanders (as described by Roth) the woman is supine and the man squats on his heels with her thighs clasping his flanks, while he raises her buttocks with his hands.

The position of coitus in which the man is supine is without doubt a natural and frequent variation of the specifically human obverse method of coitus. It was evidently familiar to the Romans. Ovid mentions it (Ars Amatoria, III, 777-8), recommending it to little women, and saying that Andromache was too tall to practice it with Hector. Aristophanes refers to it, and there are Greek epigrams in which women boast of their skill in riding their lovers. It has sometimes been viewed with a certain disfavor because it seems to confer a superiority on the woman. “Cursed be he,” according to a Mohammedan saying, “who maketh woman heaven and man earth.”

Of special interest is the wide prevalence of an attitude in coitus recalling that which prevails among quadrupeds. The frequency with which on the walls of Pompeii coitus is represented with the woman bending forward and her partner approaching her posteriorly has led to the belief that this attitude was formerly very common in Southern Italy. However that may be, it is certainly normal at the present day among various more or less primitive peoples in whom the vulva is often placed somewhat posteriorly. It is thus among the Soudanese, as also, in an altogether different part of the world, among the Eskimo Innuit and Koniags. The New Caledonians, according to Foley, cohabit in the quadrupedal manner, and so also the Papuans of New Guinea (Bongu), according to Vahness. The same custom is also found in Australia, where, however other postures are also adopted. In Europe the quadrupedal posture would seem to prevail among some of the South Slavs, notably the Dalmatians. (The different methods of coitus practiced by the South Slavs are described in Kryptadia vol. vi, pp. 220, et seq.)

This method of coitus was recommended by Lucretius (lib. iv) and also advised by Paulus AEginetus as favorable to conception. (The opinions of various early physicians are quoted by Schurig, Spermatologia, 1720, pp. 232, et seq.). It seems to be a position that is not infrequently agreeable to women, a fact which may be brought into connection with the remarks of Adler already quoted concerning the comparative lack of adjustment of the feminine organs to the obverse position. It is noteworthy that in the days of witchcraft hysterical women constantly believed that they had had intercourse with the Devil in this manner. This circumstance, indeed, probably aided in the very marked disfavor in which coitus a posteriori fell after the decay of classic influences. The mediaeval physicians described it as mos diabolicus and mistakenly supposed that it produced abortion (Hyrtl, op. cit., vol. ii, . The theologians, needless to say, were opposed to the mos diabolicus, and already in the Anglo-Saxon Penitential of Theodore, at the end of the seventh century, 40 days’ penance is prescribed for this method of coitus.

From the frequency with which they have been adopted by various peoples as national customs, most of the postures in coitus here referred to must be said to come within the normal range of variation. It is a mistake to regard them as vicious perversions.

Up to the point to which we have so far considered it, the process of detumescence has been mainly nervous and vascular in character; it has, in fact, been but the more acute stage of a process which has been going on throughout tumescence. But now we reach the point at which a new element comes in: muscular action. With the onset of muscular action, which is mainly involuntary, even when it affects the voluntary muscles, detumescence proper begins to take place. Henceforward purposeful psychic action, except by an effort, is virtually abolished. The individual, as a separate person, tends to disappear. He has become one with another person, as nearly one as the conditions of existence ever permit; he and she are now merely an instrument in the hands of a higher power-by whatever name we may choose to call that Power-which is using them for an end not themselves.

The decisive moment in the production of the instinctive and involuntary orgasm occurs when, under the influence of the stimulus applied to the penis by friction with the vagina, the tension of the seminal fluid poured into the urethra arouses the ejaculatory center in the spinal cord and the bulbo-cavernosus muscle surrounding the urethra responsively contracts in rhythmic spasms. Then it is that ejaculation occurs.

“The circulation quickens, the arteries beat strongly,” wrote Roubaud in a description of the physical state during coitus which may almost be termed classic; “the venous blood, arrested by muscular contraction, increases the general heat, and this stagnation, more pronounced in the brain by the contraction of the muscles of the neck and the throwing of the head backward, causes a momentary cerebral congestion, during which intelligence is lost and the faculties abolished. The eyes, violently injected, become haggard, and the look uncertain, or, in the majority of cases, the eyes are closed spasmodically to avoid the contact of the light. The respiration is hurried, sometimes interrupted, and may be suspended by the spasmodic contraction of the larynx, and the air, for a time compressed, is at last emitted in broken and meaningless words. The congested nervous centers only communicate confused sensations and volitions; mobility and sensation show extreme disorder; the limbs are seized by convulsions and sometimes by cramps, or are thrown wildly about or become stiff like iron bars. The jaws, tightly pressed, grind the teeth, and in some persons the delirium is carried so far that they bite to bleeding the shoulders their companions have imprudently abandoned to them. This frantic state of epilepsy lasts but a short time, but it suffices to exhaust the forces of the organism, especially in man. It is, I believe, Galen, who said: ’Omne animal post coitum triste praeter mulierem gallumque.’" Most of the elements that make up this typical picture of the state of coitus are not absolutely essential to that state, but they all come within the normal range of variation. There can be no doubt that this range is considerable. There would appear to be not only individual, but also racial, differences; there is a remarkable passage in Vatsyayana’s Kama Sutra describing the varying behavior of the women of different races in India under the stress of sexual excitement-Dravidian women with difficulty attaining erethism, women of the Punjaub fond of being caressed with the tongue, women of Oude with impetuous desire and profuse flow of mucus, etc.-and it is highly probable, Ploss and Bartels remark, that these characterizations are founded on exact observations.

The various phenomena included in Roubaud’s description of the condition during coitus may all be directly or indirectly reduced to two groups: the first circulatory and respiratory, the second motor. It is necessary to consider both these aspects of the process of detumescence in somewhat greater detail, although while it is most convenient to discuss them separately, it must be borne in mind that they are not really separable; the circulatory phenomena are in large measure a by-product of the involuntary motor process.

With the approach of detumescence the respiration becomes shallow, rapid, and to some extent arrested. This characteristic of the breathing during sexual excitement is well recognized; so that in, for instance, the Arabian Nights, it is commonly noted of women when gazing at beautiful youths whose love they desired, that they ceased breathing. It may be added that exactly the same tendency to superficial and arrested respiration takes place whenever there is any intense mental concentration, as in severe intellectual work.

The arrest of respiration tends to render the blood venous, and thus aids in stimulating the vasomotor centers, raising the blood-pressure in the body generally, and especially in the erectile tissues. High blood-pressure is one of the most marked features of the state of detumescence. The heart beats are stronger and quicker, the surface arteries are more visible, the conjunctivae become red. The precise degree of blood-pressure attained during coitus has been most accurately ascertained in the dog. In Bechterew’s laboratory in St. Petersburg a manometer was introduced into the central end of the carotid artery of a bitch; a male dog was then introduced, and during coitus observations were made on the blood-pressure at the peripheral and central ends of the artery. It was found that there was a great general elevation of blood-pressure, intense hyperaemia of the brain, rapid alternations, during the act, of vasoconstriction and vasodilatation of the brain, with increase and diminution of the general arterial tension in relation with the various phases of the act, the greatest cerebral vasodilatation and hyperaemia coinciding with the moment following the intromission of the penis; the end of the act is followed by a considerable fall in the blood-pressure. I am not acquainted with any precise observations on the blood-pressure in human subjects during detumescence, and there are obvious difficulties in the way of such observations. It is probable, however, that the conditions found would be substantially the same. This is indicated, so far as the very marked increase of blood-pressure is concerned, by some observations made by Vaschide and Vurpas with the sphygmanometer on a lady under the influence of sexual excitement. In this case there was a relationship of sympathy and friendly tenderness between the experimenter and the subject, Madame X, aged 25. Experimenter and subject talked sympathetically, and finally, we are told, while the latter still had her hands in the sphygmanometer, the former almost made a declaration of love. Madame X was greatly impressed, and afterward admitted that her emotions had been genuine and strong. The blood-pressure, which was in this subject habitually 65 millimeters, rose to 150 and even 160, indicating a very high pressure, which rarely occurs; at the same time Madame X looked very emotional and troubled.

Some authorities are of opinion that irregularities in the accomplishment of the sexual act are specially liable to cause disturbances in the circulation. Thus Kisch, of Prague, refers to the case of a couple practising coitus interruptus-the husband withdrawing before ejaculation-in which the wife, a vigorous woman, became liable after some years to attacks termed by Kisch neurasthenia cordis vasomotoria, in which there was at daily or longer intervals palpitation, with feelings of anxiety, headache, dizziness, muscular weakness and tendency to faint. He regards coitus as a cause of various heart troubles in women: (1) Attacks of tachycardia in very excitable and sexually inclined women; (2) attacks of tachycardia with dyspnoea in young women, with vaginismus; (3) cardiac symptoms with lowered vascular tone in women who for a long time have practised coitus interruptus without complete sexual gratification (Kisch, “Herzbeschwerden der Frauen verursacht durch den Cohabitationsact,” Muenchener Medizinisches Wochenschrift, 1897, . In this connection, also, reference may probably be made to those attacks of anxiety which Freud associates with psychic sexual lesions of an emotional character.

Associated with this vascular activity in detumescence we find a general tendency to glandular activity. Various secretions are formed abundantly. Perspiration is copious, and the ancient relationship between the cutaneous and sexual systems seems to evoke a general activity of the skin and its odoriferous secretions. Salivation, which also occurs, is very conspicuous in many lower animals, as for instance in the donkey, notably the female, who just before coitus stands with mouth open, jaws moving, and saliva dribbling. In men, corresponding to the more copious secretion in women, there is, during the latter stages of tumescence, a slight secretion of mucus-Fuerbringer’s urethrorrhoea ex libidine-which appears in drops at the urethral orifice. It comes from the small glands of Littre and Cowper which open into the urethra. This phenomenon was well known to the old theologians, who called it distillatio, and realized its significance as at once distinct from semen and an indication that the mind was dwelling on voluptuous images; it was also known in classic times; more recently it has often been confused with semen and has thus sometimes caused needless anxiety to nervous persons. There is also an increased secretion of urine, and it is probable that if the viscera were more accessible to observation we might be able to demonstrate that the glands throughout the body share in this increased activity.

The phenomena of detumescence culminate, however, and have their most obvious manifestation in motor activity. The genital act, as Vaschide and Vurpas remark, consists essentially in “a more and more marked tension of the motor state which, reaching its maximum, presents a short tonic phase, followed by a clonic phase, and terminates in a period of adynamia and repose.” This motor activity is of the essence of the impulse of detumescence, because without it the sperm cells could not be brought into the neighborhood of the germ cell and be propelled into the organic nest which is assigned for their conjunction and incubation.

The motor activity is general as well as specifically sexual. There is a general tendency to more or less involuntary movement, without any increase of voluntary muscular power, which is, indeed, decreased, and Vaschide and Vurpas state that dynamometric results are somewhat lower than normal during sexual excitement, and the variations greater. The tendency to diffused activity of involuntary muscle is well illustrated by the contraction of the bladder associated with detumescence. While this occurs in both sexes, in men erection produces a mechanical impediment to any evacuation of the bladder. In women there is not only a desire to urinate but, occasionally, actual urination. Many quite healthy and normal women have, as a rare accident supervening on the coincidence of an unusually full bladder with an unusual degree of sexual excitement, experienced a powerful and quite involuntary evacuation of the bladder at the moment of orgasm. In women with less normal nervous systems this has, more rarely, been almost habitual. Brantome has perhaps recorded the earliest case of this kind in referring to a lady he knew who “quand on lui faisait cela elle se compissait a bon escient." The tendency to trembling, constriction of throat, sneezing, emission of internal gas, and the other similar phenomena occasionally associated with detumescence, are likewise due to diffusion of the motor disturbance. Even in infancy the motor signs of sexual excitement are the most obvious indications of orgasm; thus West, describing masturbation in a child of six or nine months who practiced thigh-rubbing, states that when sitting in her high chair she would grasp the handles, stiffen herself, and stare, rubbing her thighs quickly together several times, and then come to herself with a sigh, tired, relaxed, and sweating, these seizures, which lasted one or two minutes, being mistaken by the relations for epileptic fits.

The essentially motor character of detumescence is well shown by the extreme forms of erotic intoxication which sometimes appear as the result of sexual excitement. Fere, who has especially called attention to the various manifestations of this condition, presents an instructive case of a man of neurotic heredity and antecedents, in whom it occasionally happened that sexual excitement, instead of culminating in the normal orgasm, attained its climax in a fit of uncontrollable muscular excitement. He would then sing, dance, gesticulate, roughly treat his partner, break the objects around him, and finally sink down exhausted and stupefied. (Fere, L’Instinct Sexuel, Chapter X.) In such a case a diffused and general detumescence has taken the place of the normal detumescence which has its main focus in the sexual sphere.

The same relationship is shown in a case of impotence accompanied by cramps in the calves and elsewhere, which has been recorded by Bruegelmann ("Zur Lehre vom Perversen Sexualismus,” Zeitschrift fuer Hypnotismus, 1900, Heft I). These muscular conditions ceased for several days whenever coitus was effected.

An instructive analogy to the motor irradiations preceding the moment of sexual detumescence may be found in the somewhat similar motor irradiations which follow the delayed expulsion of a highly distended bladder. These sometimes become very marked in a child or young woman unable to control the motor system absolutely. The legs are crossed, the foot swung, the thighs tightly pressed together, the toes curled. The fingers are flexed in rhythmic succession. The whole body slowly twists as though the seat had become uncomfortable. It is difficult to concentrate the mind; the same remark may be automatically repeated; the eyes search restlessly, and there is a tendency to count surrounding objects or patterns. When the extreme degree of tension is reached it is only by executing a kind of dance that the explosive contraction of the bladder is restrained.

The picture of muscular irradiation presented under these circumstances differs but slightly from that of the onset of detumescence. In one case the explosion is sought, in the other case it is dreaded; but in both cases there is a retarded muscular tension,-in the one case involuntary, in the other case voluntary-maintained at a point of acute intensity, and in both cases the muscular irradiations of this tension spread over the whole body.

The increased motor irritability of the state of detumescence somewhat resembles the conditions produced by a weak anæsthetic and there is some interest in noting the sexual excitement liable to occur in anæsthesia. I am indebted to Dr. J.F.W. Silk for some remarks on this point:-

“I. Sexual emotions may apparently be aroused during the stage of excitement preceding or following the administration of any anæsthetic; these emotions may take the form of mere delirious utterances, or may be associated with what is apparently a sexual orgasm. Or reflex phenomena connected with the sexual organs may occasionally be observed under special circumstances; or, to put it in another way, such reflex possibilities are not always abolished by the condition of narcosis or anæsthesia.

“II. Of the particular anaesthetics employed I am inclined to think that the possibility of such conditions arising is inversely proportionate to their strength, e.g., they are more frequently observed with a weak anæsthetic like nitrous oxide than with chloroform.

“III. Sexual emotions I believe to be rarely observable in men, and this is remarkable, or, I should say, particularly noticeable, for the presence of nurses, female students, etc., might almost have led one to expect that the contrary would have been the case. On the other hand, it is among men that I have frequently observed a reflex phenomenon which has usually taken the shape of an erection of the penis when the structures in the neighborhood of the spermatic cord have been handled.

“IV. Among females the emotional sexual phenomena most frequently obtrude themselves, and I believe that if it were possible to induce people to relate their dreams they would very often be found to be of a sexual character.”

Much more important than the general motor phenomena, more purposive though involuntary, are the specifically sexual muscular movements. From the very beginning of detumescence, indeed, muscular activity makes itself felt, and the peripheral muscles of sex act, according to Kobelt’s expression, as a peripheral sexual heart. In the male these movements are fairly obvious and fairly simple. It is required that the semen should be expressed from the vesiculae seminales, propelled along the urethra, in combination with the prostatic fluid which is equally essential, and finally ejected with a certain amount of force from the urethral orifice. Under the influence of the stimulation furnished by the contact and friction of the vagina, this process is effectively carried out, mainly by the rhythmic contractions of the bulbo-cavernosus muscle, and the semen is emitted in a jet which may be ejaculated to a distance varying from a few centimeters to a meter or more.

With regard to the details of the psychic sides of this process a correspondent, a psychologist, writes as follows:-

“I have never noticed in my reading any attempt to analyze the sensations which accompany the orgasm, and, as I have made a good many attempts to make such an analysis myself, I will append the results on the chance that they may be of some value. I have checked my results so far as possible by comparing them with the experience of such of my friends as had coitus frequently and were willing to tell me as much as they could of the psychology of the process.

“The first fact that I hit upon was the importance of pressure. As one of my informants picturesquely phrases it-’the tighter the fit the greater the pleasure.’ This agrees, too, with their unanimous testimony that the pleasurable sensations were much greater when the orgasm occurred simultaneously in the man and woman. Their analysis seldom went further than this, but a few remarked that the distinctive sensations accompanying the orgasm seem to begin near the root of the penis or in the testes, and that they are qualitatively different from the tickling sensations which precede them.

“These tickling sensations are caused, I think, by the friction of the glands against the vaginal walls, and are supplemented by other sensations from the urethra, whose nerves are stimulated by pressure of the vaginal walls and sphincter. The specific sensation of the orgasm begins, I believe, with a strong contraction of the muscles of the urethral walls along the entire length of the canal, and is felt as a peculiar ache starting from the base of the penis and quickly becoming diffused through the whole organ. This sensation reaches its climax with the expulsion of the semen into the urethra and the consequent feeling of distention, which is instantly followed by the rhythmic peristaltic contractions of the urethral muscles which mark the climax of the orgasm.

“The most careful introspection possible under the circumstances seems to show that these sensations arise almost wholly from the urethra and in a far less degree from the corona. During periods of great sexual excitement the nerves of the urethra and corona seem to possess a peculiar sensitivity and are powerfully stimulated by the violent peristaltic contractions of the muscles in the urethral walls during ejaculation. It seems possible that the intensity and volume of sensation felt at the glans may be due in part to the greater area of sensitive surface presented in the fossa as well as to the sensitivity of the corona, and in part to the fact that during the orgasm the glans is more highly congested than at any other time, and the nerve endings thus subjected to additional pressure.

“If the foregoing statements are true, it is easy to see why the pleasure of the man is much increased when the orgasm occurs at the same time in his partner and himself, for the contractions of the vagina upon the penis would increase the stimulation of all the nerve endings in that organ for which a mechanical stimulus is adequate, and the prominence of the corpus spongiosum and corona would ensure them the greatest stimulation. It seems not improbable that the specific sensation of orgasm rises from the stimulation of the peculiar form of nerve end-bulbs which Krause found in the corpus spongiosum and in the glans.

“The characteristic massiveness of the experience is probably due largely to the great number of sensations of strain and pressure caused by the powerful reflex contraction of so many of the voluntary muscles.

“Of course, the foregoing analysis is purely tentative, and I offer it only on the chance that it may suggest some line of inquiry which may lead to results of value to the student of sexual psychology.”

In man the whole process of detumescence, when it has once really begun, only occupies a few moments. It is so likewise in many animals; in the genera Bos, Ovis, etc., it is very short, almost instantaneous, and rather short also in the Equidae (in a vigorous stallion, according to Colin, ten to twelve seconds). As Disselhorst has pointed out, this is dependent on the fact that these animals, like man, possess a vas deferens which broadens into an ampulla serving as a receptacle which holds the semen ready for instant emission when required. On the other hand, in the dog, cat, boar, and the Canidae, Felidae, and Suidae generally, there is no receptacle of this kind, and coitus is slow, since a longer time is required for the peristaltic action of the vas to bring the semen to the urogenital sinus. (R. Disselhorst, Die Accessorischen Geschlechtsdrusen der Wirbelthiere, 1897, .)

In man there can be little doubt that detumescence is more rapidly accomplished in the European than in the East, in India, among the yellow races, or in Polynesia. This is probably in part due to a deliberate attempt to prolong the act in the East, and in part to a greater nervous erethism among Westerns.

In the woman the specifically sexual muscular process is less visible, more obscure, more complex, and uncertain. Before detumescence actually begins there are at intervals involuntary rhythmic contractions of the walls of the vagina, seeming to have the object of at once stimulating and harmonizing with those that are about to begin in the male organ. It would appear that these rhythmic contractions are the exaggeration of a phenomenon which is normal, just as slight contraction is normal and constant in the bladder. Jastreboff has shown, in the rabbit, that the vagina is in constant spontaneous rhythmic contraction from above downward, not peristaltic, but in segments, the intensity of the contractions increasing with age and especially with sexual development. This vaginal contraction which in women only becomes well marked just before detumescence, and is due mainly to the action of the sphincter cunni (analogous to the bulbo-cavernosus in the male), is only a part of the localized muscular process. At first there would appear to be a reflex peristaltic movement of the Fallopian tubes and uterus. Dembo observed that in animals stimulation of the upper anterior wall of the vagina caused gradual contraction of the uterus, which is erected by powerful contraction of its muscular fiber and round ligaments while at the same time it descends toward the vagina, its cavity becoming more and more diminished and mucus being forced out. In relaxing, Aristotle long ago remarked, it aspirates the seminal fluid.

Although the active participation of the sexual organs in woman, to the end of directing the semen into the womb at the moment of detumescence, is thus a very ancient belief, and harmonizes with the Greek view of the womb as an animal in the body endowed with a considerable amount of activity, precise observation in modern times has offered but little confirmation of the reality of this participation. Such observations as have been made have usually been the accidental result of sexual excitement and orgasm occurring during a gynaecological examination. As, however, such a result is liable to occur in erotic subjects, a certain number of precise observations have accumulated during the past century. So far as the evidence goes, it would seem that in women, as in mares, bitches, and other animals, the uterus becomes shorter, broader, and softer during the orgasm, at the same time descending lower into the pelvis, with its mouth open intermittently, so that, as one writer remarks, spontaneously recurring to the simile which commended itself to the Greeks, “the uterus might be likened to an animal gasping for breath." This sensitive, responsive mobility of the uterus is, indeed, not confined to the moment of detumescence, but may occur at other times under the influence of sexual emotion.

It would seem probable that in this erection, contraction, and descent of the uterus, and its simultaneous expulsion of mucus, we have the decisive moment in the completion of detumescence in woman, and it is probable that the thick mucus, unlike the earlier more limpid secretion, which women are sometimes aware of after orgasm, is emitted from the womb at this time. This is, however, not absolutely certain. Some authorities regard detumescence in women as accomplished in the pouring out of secretions, others in the rhythmic genital contractions; the sexual parts may, however, be copiously bathed in mucus for an indefinitely long period before the final stage of detumescence is achieved, and the rhythmic contractions are also taking place at a somewhat early period; in neither respect is there any obvious increase at the final moment of orgasm. In women this would seem to be more conspicuously a nervous manifestation than in men. On the subjective side it is very pronounced, with its feeling of relieved tension and agreeable repose-a moment when, as one woman expresses it, together with intense pleasure, there is, as it were, a floating up into a higher sphere, like the beginning of chloroform narcosis-but on the objective side this culminating moment is less easy to define.

Various observations and remarks made during the past two or three centuries by Bond, Valisneri, Dionis, Haller, Guenther, and Bischoff, tending to show a sucking action of the uterus in both women and other female animals, have been brought together by Litzmann in R. Wagner’s Handwoerterbuch der Physiologie (1846, vol. iii, . Litzmann added an experience of his own: “I had an opportunity lately, while examining a young and very erethic woman, to observe how suddenly the uterus assumed a more erect position, and descended deeper in the pelvis; the lips of the womb became equal in length, the cervix rounded, softer, and more easily reached by the finger, and at the same time a high state of sexual excitement was revealed by the respiration and voice.”

The general belief still remained, however, that the woman’s part in conjugation is passive, and that it is entirely by the energy of the male organ and of the male sexual elements, the spermatozoa, that conjunction with the germ cell is attained. According to this theory, it was believed that the spermatozoa were, as Wilkinson expresses it, in a history of opinion on this question, “endowed with some sort of intuition or instinct; that they would turn in the direction of the os uteri, wading through the acid mucus of the vagina; travel patiently upward and around the vaginal portion of the uterus; enter the uterus and proceed onward in search of the waiting ovum.” (A.D. Wilkinson, “Sterility in the Female,” Transactions of the Lincoln Medical Society, Nebraska, 1896.)

About the year 1859 Fichstedt seems to have done something to overthrow this theory by declaring his belief that the uterus was not, as commonly supposed, a passive organ in coitus, but was capable of sucking in the semen during the brief period of detumescence. Various authorities then began to bring forward arguments and observations in the same sense. Wernich, especially, directed attention to this point in 1872 in a paper on the erectile properties of the lower segment of the uterus ("Die Erectionsfahigkeit des untern Uterus-Abschnitts,” Beitraege zur Geburtshuelfe und Gynaekologie, vol. i, . He made precise observations and came to the conclusion that owing to erectile properties in the neck of the uterus, this part of the womb elongates during congress and reaches down into the pelvis with an aspiratory movement, as if to meet the glans of the male. A little later, in a case of partial prolapse, Beck, in ignorance of Wernich’s theory, was enabled to make a very precise observation of the action of the uterus during excitement. In this case the woman was sexually very excitable even under ordinary examination, and Beck carefully noted the phenomena that took place during the orgasm. “The os and cervix uteri,” he states, “had been about as firm as usual, moderately hard and, generally speaking, in a natural and normal condition, with the external os closed to such an extent as to admit of the uterine probe with difficulty; but the instant that the height of excitement was at hand, the os opened itself to the extent of fully an inch, as nearly as my eye can judge, made five or six successive gasps as if it were drawing the external os into the cervix, each time powerfully, and, it seemed to me, with a regular rhythmical action, at the same time losing its former density and hardness and becoming quite soft to the touch. Upon the cessation of the action, as related, the os suddenly closed, the cervix again hardened itself, and the intense congestion was dissipated.” (J.R. Beck, “How do the Spermatozoa Enter the Uterus?” American Journal of Obstetrics, 1874.) It would appear that in the early part of this final process of detumescence the action of the uterus is mainly one of contraction and ejaculation of any mucus that may be contained; Dr. Paul Munde has described “the gushing, almost in jets,” of this mucus which he has observed in an erotic woman under a rather long digital and specular examination. (American Journal of Obstetrics, 1893.) It is during the latter part of detumescence, it would seem, and perhaps for a short time after the orgasm is over, that the action of the uterus is mainly aspiratory.

While the active part played by the womb in detumescence can no longer be questioned, it need not too hastily be assumed that the belief in the active movements of the spermatozoa must therefore be denied. The vigorous motility of the tadpole-like organisms is obvious to anyone who has ever seen fresh semen under the microscope; and if it is correct, as Clifton Edgar states, that the spermatozoa may retain their full activity in the female organs for at least seventeen days, they have ample time to exert their energies. The fact that impregnation sometimes occurs without rupture of the hymen is not decisive evidence that there has been no penetration, as the hymen may dilate without rupturing; but there seems no reason to doubt that conception has sometimes taken place when ejaculation has occurred without penetration; this is indicated in a fairly objective manner when, as has been occasionally observed, conception has occurred in women whose vaginas were so narrow as scarcely to admit the entrance of a goose-quill; such was the condition in the case of a pregnant woman brought forward by Roubaud. The stories, repeated in various books, of women who have conceived after homosexual relations with partners who had just left their husbands’ beds are not therefore inherently impossible. Janke quotes numerous cases in which there has been impregnation in virgins who have merely allowed the penis to be placed in contact with the vulva, the hymen remaining unruptured until delivery.

It must be added, however, that even if the semen is effused merely at the mouth of the vagina, without actual penetration, the spermatozoa are still not entirely without any resource save their own motility in the task of reaching the ovum. As we have seen, it is not only the uterus which takes an active part in detumescence; the vagina also is in active movement, and it seems highly probable that, at all events in some women and under some circumstances, such movement favoring aspiration toward the womb may be communicated to the external mouth of the vagina.

Riolan (Anthropographia, 1626, referred to the constriction and dilation of the vulva under the influence of sexual excitement. It is said that in Abyssinia women can, when adopting the straddling posture of coitus, by the movements of their own vaginal muscles alone, grasp the male organ and cause ejaculation, although the man remains passive. According to Lorion the Annamites, adopting the normal posture of coitus, introduce the penis when flaccid or only half erect, the contraction of the vaginal walls completing the process; the penis is very small in this people. It is recognized by gynaecologists that the condition of vaginismus, in which there is spasmodic contraction of the vagina, making intercourse painful or impossible, is but a morbid exaggeration of the normal contraction which occurs in sexual excitement. Even in the absence of sexual excitement there is a vague affection, occurring in both married and unmarried women, and not, it would seem, necessarily hysterical, characterized by quivering or twitching of the vulva; I am told that this is popularly termed “flackering of the shape” in Yorkshire and “taittering of the lips” in Ireland. It may be added that quivering of the gluteal muscles also takes place during detumescence, and that in Indian medicine this is likewise regarded as a sign of sexual desire in women, apart from coitus.

A non-medical correspondent in Australia, W.J. Chidley, from whom I have received many communications on this subject, is strongly of opinion from his own observations that not only does the uterus take an active part in coitus, but that under natural conditions the vagina also plays an active part in the process. He was led to suspect such an action many years ago, as well by an experience of his own, as also by hearing from a young woman who met her lover after a long absence that by the excitement thus aroused a tape attached to the underclothes had been drawn into the vagina. Since then the confidences of various friends, together with observations of animals, have confirmed him in the view that the general belief that coitus must be effected by forcible entry of the male organ into a passive vagina is incorrect. He considers that under normal circumstances coitus should take place but rarely, and then only under the most favorable circumstances, perhaps exclusively in spring, and, most especially, only when the woman is ready for it. Then, when in the arms of the man she loves, the vagina, in sympathy with the active movements of the womb, becomes distended at the touch of the turgescent, but not fully erect, penis, “flashes open and draws in the male organ.” “All animals,” he adds, “have sexual intercourse by the male organ being drawn, not forced, into the female. I have been borne out in this by friends who have seen horses, camels, mules and other large animals in the coupling season. What is more absurd, for instance, than to say that an entire penetrates the mare? His penis is a sensitive, beautiful piece of mechanism, which brings its light head here and there till it touches the right spot, when the mare, if ready, takes it in. An entire’s penis could not penetrate anything; it is a curve, a beautiful curve which would easily bend. A bull’s, again, is turned down at the end and, more palpably still, would fold on itself if pressed with force. The womb and vagina of a beautiful and healthy woman constitute a living, vital, moving organ, sensitive to a look, a word, a thought, a hand on the waist.”

A well-known American author thus writes in confirmation of the foregoing view: “In nature the woman wooes. When impassioned her vagina becomes erect and dilated, and so lubricated with abundant mucus to the lips that entrance is easy. This dilatation and erectile expansion of vagina withdraws the hymen so close to the walls that penetration need not tear it or cause pain. The more muscular, primitive and healthy the woman the tougher and less sensitive the hymen, and the less likely to break or bleed. I think one great function of the foreskin also is to moisten the glans, so that it can be lubricated for entrance, and then to retract, moist side out, to make entrance still easier. I think that in nature the glans penetrates within the labia, is withstood a moment, vibrating, and then all resistance is withdrawn by a sudden ‘flashing open’ of the gates, permitting easy entrance, and that the sudden giving up of resistance, and substitution of welcome, with its instantaneous deep entrance, causes an almost immediate male orgasm (the thrill being irresistibly exciting). Certainly this is the process as observed in horses, cattle, goats, etc., and it seems likely something analogous is natural in man.”

While it is easily possible to carry to excess a view which would make the woman rather than the man the active agent in coitus (and it may be recalled that in the Cebidae the penis, as also the clitoris, is furnished with a bone), there is probably an element of truth in the belief that the vagina shares in the active part which, there can now be little doubt, is played by the uterus in detumescence. Such a view certainly enables us to understand how it is that semen effused on the exterior sexual organs can be conveyed to the uterus.

It was indeed the failure to understand the vital activity of the semen and the feminine genital canal, co-operating together towards the junction of sperm cell and germ cell, which for so long stood in the way of the proper understanding of conception. Even the genius of Harvey, which had grappled successfully with the problem of the circulation, failed in the attempt to comprehend the problem of generation. Mainly on account of this difficulty, he was unable to see how the male element could possibly enter the uterus, although he devoted much observation and study to the question. Writing of the uterus of the doe after copulation, he says: “I began to doubt, to ask myself whether the semen of the male could by any possibility make its way by attraction or injection to the seat of conception, and repeated examination led me to the conclusion that none of the semen reached this seat.” (De-Generatione Animalium, Exercise lxvii.) “The woman,” he finally concluded, “after contact with the spermatic fluid in coitu, seems to receive an influence and become fecundated without the co-operation of any sensible corporeal agent, in the same way as iron touched by the magnet is endowed with its powers.”

Although the specifically sexual muscular process of detumescence in women-as distinguished from the general muscular phenomena of sexual excitement which may be fairly obvious-is thus seen to be somewhat complex and obscure, in women as well as in men detumescence is a convulsion which discharges a slowly accumulated store of nervous force. In women also, as in men, the motor discharge is directed to a specific end-the intromission of the semen in the one sex, its reception in the other. In both sexes the sexual orgasm and the pleasure and satisfaction associated with it, involve, as their most essential element, the motor activity of the sexual sphere.

The active co-operation of the female organs in detumescence is probably indicated by the difficulty which is experienced in achieving conception by the artificial injection of semen. Marion Sims stated in 1866, in Clinical Notes on Uterine Surgery, that in 55 injections in six women he had only once been successful; he believed that that was the only case at that time on record. Jacobi had, however, practiced artificial fecundation in animals (in 1700) and John Hunter in man. See Gould and Pyle, Anomalies and Curiosities of Medicine, ; also Janke (Die Willkuerliche Hervorbringen des Geschlechts, pp. 230 et seq.) who discusses the question of artificial fecundation and brings together a mass of data.

The facial expression when tumescence is completed is marked by a high degree of energy in men and of loveliness in women. At this moment, when the culminating act of life is about to be accomplished, the individual thus reaches his supreme state of radiant beauty. The color is heightened, the eyes are larger and brighter, the facial muscles are more tense, so that in mature individuals any wrinkles disappear and youthfulness returns.

At the beginning of detumescence the features are frequently more discomposed. There is a general expression of eager receptivity to sensory impressions. The dilatation of the pupils, the expansion of the nostrils, the tendency to salivation and to movements of the tongue, all go to make up a picture which indicates an approaching gratification of sensory desires; it is significant that in some animals there is at this moment erection of the ears. There is sometimes a tendency to utter broken and meaningless words, and it is noted that sometimes women have called out on their mothers. The dilatation of the pupils produces photophobia, and in the course of detumescence the eyes are frequently closed from this cause. At the beginning of sexual excitement, Vaschide and Vurpas have observed, tonicity of the eye-muscles seems to increase; the elevators of the upper lids contract, so that the eyes look larger and their mobility and brightness are heightened; with the increase of muscular tonicity strabismus occurs, owing to the greater strength of the muscles that carry the eyes inward.

The facial expression which marks the culmination of tumescence, and the approach of detumescence is that which is generally expressive of joy. In an interesting psycho-physical study of the emotion of joy, Dearborn thus summarizes its characteristics: “The eyes are brighter and the upper eyelid elevated, as also are the brows, the skin over the glabella, the upper lip and the corners of the mouth, while the skin at the outer canthi of the eye is puckered. The nostrils are moderately dilated, the tongue slightly extended and the cheeks somewhat expanded, while in persons with largely developed pinnal muscles the ears tend somewhat to incline forwards. The whole arterial system is dilated, with consequent blushing from this effect on the dermal capillaries of the face, neck, scalp and hands, and sometimes more extensively even; from the same cause the eyes slightly bulge. The whole glandular system likewise is stimulated, causing the secretions,-gastric, salivary, lachrymal, sudoral, mammary, genital, etc.-to be increased, with the resulting rise of temperature and increase in the katobolism generally. Volubility is almost regularly increased, and is, indeed, one of the most sensitive and constant of the correlations in emotional delight.... Pleasantness is correlated in living organisms by vascular, muscular and glandular extension or expansion, both literal and figurative.” (G. Dearborn, “The Emotion of Joy,” Psychological Review Monograph Supplements, vol. ii, N, .) All these signs of joy appear to occur at some stage of the process of sexual excitement.

In some monkeys it would seem that the muscular movement which in man has become the smile is the characteristic facial expression of sexual tumescence or courtship. Discussing the facial expression of pleasure in children, S.S. Buckman has the following remarks: “There is one point in such expression which has not received due consideration, namely, the raising of lumps of flesh each side of the nose as an indication of pleasure. Accompanying this may be seen small furrows, both in children and adults, running from the eyes somewhat obliquely towards the nose. What these characters indicate may be learned from the male mandril, whose face, particularly in the breeding season, shows colored fleshy prominences each side of the nose, with conspicuous furrows and ridges. In the male mandril these characters have been developed because, being an unmistakable sign of sexual ardor, they gave the female particular evidence of sexual feelings. Thus such characters would come to be recognized as habitually symptomatic of pleasurable feelings. Finding similar features in human beings, and particularly in children, though not developed in the same degree, we may assume that in our monkey-like ancestors facial characters similar to those of the mandril were developed, though to a less extent, and that they were symptomatic of pleasure, because connected with the period of courtship. Then they became conventionalized as pleasurable symptoms.” (S.S. Buckmann, “Human Babies: What They Teach,” Nature, July 5, 1900.) If this view is accepted, it may be said that the smile, having in man become a generalized sign of amiability, has no longer any special sexual significance. It is true that a faint and involuntary smile is often associated with the later stages of tumescence, but this is usually lost during detumescence, and may even give place to an expression of ferocity.

When we have realized how profound is the organic convulsion involved by the process of detumescence, and how great the general motor excitement involved, we can understand how it is that very serious effects may follow coitus. Even in animals this is sometimes the case. Young bulls and stallions have fallen in a faint after the first congress; boars may be seriously affected in a similar way; mares have been known even to fall dead. In the human species, and especially in men-probably, as Bryan Robinson remarks, because women are protected by the greater slowness with which detumescence occurs in them-not only death itself, but innumerable disorders and accidents have been known to follow immediately after coitus, these results being mainly due to the vascular and muscular excitement involved by the processes of detumescence. Fainting, vomiting, urination, defaecation have been noted as occurring in young men after a first coitus. Epilepsy has been not infrequently recorded. Lesions of various organs, even rupture of the spleen, have sometimes taken place. In men of mature age the arteries have at times been unable to resist the high blood-pressure, and cerebral haemorrhage with paralysis has occurred. In elderly men the excitement of intercourse with strange women has sometimes caused death, and various cases are known of eminent persons who have thus died in the arms of young wives or of prostitutes.

These morbid results, are, however, very exceptional. They usually occur in persons who are abnormally sensitive, or who have imprudently transgressed the obvious rules of sexual hygiene. Detumescence is so profoundly natural a process; it is so deeply and intimately a function of the organism, that it is frequently harmless even when the bodily condition is far from absolutely sound. Its usual results, under favorable circumstances, are entirely beneficial. In men there normally supervenes, together with the relief from the prolonged tension of tumescence, with the muscular repose and falling blood-pressure, a sense of profound satisfaction, a glow of diffused well-being, perhaps an agreeable lassitude, occasionally also a sense of mental liberation from an overmastering obsession. Under reasonably happy circumstances there is no pain, or exhaustion, or sadness, or emotional revulsion. The happy lover’s attitude toward his partner is not expressed by the well-known Sonnet (CXXIX) of Shakespeare:-

“Past reason hunted, and no sooner had Past reason hated.”

He feels rather with Boccaccio that the kissed mouth loses not its charm,

“Bocca baciata non perde ventura.”

In women the results of detumescence are the same, except that the tendency to lassitude is not marked unless the act has been several times repeated; there is a sensation of repose and self-assurance, and often an accession of free and joyous energy. After completely satisfactory detumescence she may experience a feeling as of intoxication, lasting for several hours, an intoxication that is followed by no evil reaction.

Such, so far as our present vague and imperfect knowledge extends, are the main features in the process of detumescence. In the future, without doubt, we shall learn to know more precisely a process which has been so supremely important in the life of man and of his ancestors.