Analysis of the Sexual Impulse/Analysis

The term "sexual instinct" may be said to cover the whole of the neuropsychic phenomena of reproduction which man shares with the lower animals. It is true that much discussion has taken place concerning the proper use of the term "instinct," and some definitions of instinctive action would appear to exclude the essential mechanism of the process whereby sexual reproduction is assured. Such definitions scarcely seem legitimate, and are certainly unfortunate. Herbert Spencer's definition of instinct as "compound reflex action" is sufficiently clear and definite for ordinary use.

It may be said that the whole of the task undertaken in these Studies is really an attempt to analyze what is commonly called the sexual instinct. In order to grasp it we have to break it up into its component parts. Lloyd Morgan has pointed out that the components of an instinct may be regarded as four: first, the internal messages giving rise to the impulse; secondly, the external stimuli which co-operate with the impulse to affect the nervous centers; thirdly, the active response due to the co-ordinate outgoing discharges; and, fourthly, the message from the organs concerned in the behavior by which the central nervous system is further affected.

In dealing with the sexual instinct the first two factors are those which we have most fully to discuss. With the external stimuli we shall be concerned in a future volume (IV). We may here confine ourselves mainly to the first factor: the nature of the internal messages which prompt the sexual act. We may, in other words, attempt to analyze the sexual impulse.

The first definition of the sexual impulse we meet with is that which regards it as an impulse of evacuation. The psychological element is thus reduced to a minimum. It is true that, especially in early life, the emotions caused by forced repression of the excretions are frequently massive or acute in the highest degree, and the joy of relief correspondingly great. But in adult life, on most occasions, these desires can be largely pushed into the background of consciousness, partly by training, partly by the fact that involuntary muscular activity is less imperative in adult life; so that the ideal element in connection with the ordinary excretions is almost a negligible quantity. The evacuation theory of the sexual instinct is, however, that which has most popular vogue, and the cynic delights to express it in crude language. It is the view that appeals to the criminal mind, and in the slang of French criminals the brothel is le cloaque. It was also the view implicitly accepted by medieval ascetic writers, who regarded woman as "a temple built over a sewer," and from a very different standpoint it was concisely set forth by Montaigne, who has doubtless contributed greatly to support this view of the matter: "I find," he said, "that Venus, after all, is nothing more than the pleasure of discharging our vessels, just as nature renders pleasurable the discharges from other parts." Luther, again, always compared the sexual to the excretory impulse, and said that marriage was just as necessary as the emission of urine. Sir Thomas More, also, in the second book of Utopia, referring to the pleasure of evacuation, speaks of that felt "when we do our natural easement, or when we be doing the act of generation." This view would, however, scarcely deserve serious consideration if various distinguished investigators, among whom Fere may be specially mentioned, had not accepted it as the best and most accurate definition of the sexual impulse. "The genesic need may be considered," writes Fere, "as a need of evacuation; the choice is determined by the excitations which render the evacuation more agreeable." Certain facts observed in the lower animals tend to support this view; it is, therefore, necessary, in the first place, to set forth the main results of observation on this matter. Spallanzani had shown how the male frog during coitus will undergo the most horrible mutilations, even decapitation, and yet resolutely continue the act of intercourse, which lasts from four to ten days, sitting on the back of the female and firmly clasping her with his forelegs. Goltz confirmed Spallanzani's observations and threw new light on the mechanism of the sexual instinct and the sexual act in the frog. By removing various parts of the female frog Goltz found that every part of the female was attractive to the male at pairing time, and that he was not imposed on when parts of a male were substituted. By removing various of the sense-organs of the male Goltz further found that it was not by any special organ, but by the whole of his sensitive system, that this activity was set in action. If, however, the skin of the arms and of the breast between was removed, no embrace took place; so that the sexual sensations seemed to be exerted through this apparatus. When the testicles were removed the embrace still took place. It could scarcely be said that these observations demonstrated, or in any way indicated, that the sexual impulse is dependent on the need of evacuation. Professor Tarchanoff, of St. Petersburg, however, made an experiment which seemed to be crucial. He took several hundred frogs (Rana temporaria), nearly all in the act of coitus, and in the first place repeated Goltz's experiments. He removed the heart; but this led to no direct or indirect stoppage of coitus, nor did removal of the lungs, parts of the liver, the spleen, the intestines, the stomach, or the kidneys. In the same way even careful removal of both testicles had no result. But on removing the seminal receptacles coitus was immediately or very shortly stopped, and not renewed. Thus, Tarchanoff concluded that in frogs, and possibly therefore in mammals, the seminal receptacles are the starting-point of the centripetal impulse which by reflex action sets in motion the complicated apparatus of sexual activity. A few years later the question was again taken up by Steinach, of Prague. Granting that Tarchanoff's experiments are reliable as regards the frog, Steinach points out that we may still ask whether in mammals the integrity of the seminal receptacles is bound up with the preservation of sexual excitability. This cannot be taken for granted, nor can we assume that the seminal receptacles of the frog are homologous with the seminal vesicles of mammals. In order to test the question, Steinach chose the white rat, as possessing large seminal vesicles and a very developed sexual impulse. He found that removal of the seminal sacs led to no decrease in the intensity of the sexual impulse; the sexual act was still repeated with the same frequency and the same vigor. But these receptacles, Steinach proceeded to argue, do not really contain semen, but a special secretion of their own; they are anatomically quite unlike the seminal receptacles of the frog; so that no doubt is thus thrown on Tarchanoff's observations. Steinach remarked, however, that one's faith is rather shaken by the fact that in the Esculenta, which in sexual life closely resembles Rana temporaria, there are no seminal receptacles. He therefore repeated Tarchanoff's experiments, and found that the seminal receptacles were empty before coitus, only becoming gradually filled during coitus; it could not, therefore, be argued that the sexual impulse started from the receptacles. He then extirpated the seminal receptacles, avoiding hemorrhage as far as possible, and found that, in the majority of cases so operated on, coitus still continued for from five to seven days, and in the minority for a longer time. He therefore concluded, with Goltz, that it is from the swollen testicles, not from the seminal receptacles, that the impulse first starts. Goltz himself pointed out that the fact that the removal of the testicles did not stop coitus by no means proves that it did not begin it, for, when the central nervous mechanism is once set in action, it can continue even when the exciting stimulus is removed. By extirpating the testicles some months before the sexual season he found that no coitus occurred. At the same time, even in these frogs, a certain degree of sexual inclination and a certain excitability of the embracing center still persisted, disappearing when the sexual epoch was over.

According to most recent writers, the seminal vesicles of mammals are receptacles for their own albuminous secretion, the function of which is unknown. Steinach could find no spermatozoa in these "seminal" sacs, and therefore he proposed to use Owen's name of glandulae vesiculares. After extirpation of these vesicular glands in the white rat typical coitus occurred. But the capacity for procreation was diminished, and extirpation of both glandulae vesiculares and glandulae prostaticae led to disappearance of the capacity for procreation. Steinach came to the conclusion that this is because the secretions of these glands impart increased vitality to the spermatozoa, and he points out that great fertility and high development of the accessory sexual glands go together.

Steinach found that, when sexually mature white rats were castrated, though at first they remained as potent as ever, their potency gradually declined; sexual excitement, however, and sexual inclination always persisted. He then proceeded to castrate rats before puberty and discovered the highly significant fact that in these also a quite considerable degree of sexual inclination appeared. They followed, sniffed, and licked the females like ordinary males; and that this was not a mere indication of curiosity was shown by the fact that they made attempts at coitus which only differed from those of normal males by the failure of erection and ejaculation, though, occasionally, there was imperfect erection. This lasted for a year, and then their sexual inclinations began to decline, and they showed signs of premature age. These manifestations of sexual sense Steinach compares to those noted in the human species during childhood.

The genesic tendencies are thus, to a certain degree, independent of the generative glands, although the development of these glands serves to increase the genesic ability and to furnish the impulsion necessary to assure procreation, as well as to insure the development of the secondary sexual characters, probably by the influence of secretions elaborated and thrown into the system from the primary sexual glands.

The experience of veterinary surgeons also shows that the sexual impulse tends to persist in animals after castration. Thus the ox and the gelding make frequent efforts to copulate with females in heat. In some cases, at all events in the case of the horse, castrated animals remain potent, and are even abnormally ardent, although impregnation cannot, of course, result.

The results obtained by scientific experiment and veterinary experience on the lower animals are confirmed by observation of various groups of phenomena in the human species. There can be no doubt that castrated men may still possess sexual impulses. This has been noted by observers in various countries in which eunuchs are made and employed.

In China, Matignon, formerly physician to the French legation in Pekin, tells us that eunuchs are by no means without sexual feeling, that they seek the company of women and, he believes, gratify their sexual desires by such methods as are left open to them, for the sexual organs are entirely removed. It would seem probable that, the earlier the age at which the operation is performed, the less marked are the sexual desires, for Matignon mentions that boys castrated before the age of 10 are regarded by the Chinese as peculiarly virginal and pure. At Constantinople, where the eunuchs are of negro race, castration is usually complete and performed before puberty, in order to abolish sexual potency and desire as far as possible. Even when castration is effected in infancy, sexual desire is not necessarily rendered impossible. Thus Marie has recorded the case of an insane Egyptian eunuch whose penis and scrotum were removed in infancy; yet, he had frequent and intense sexual desire with ejaculation of mucus and believed that an invisible princess touched him and aroused voluptuous sensations. Although the body had a feminine appearance, the prostate was normal and the vesiculae seminales not atrophied. It may be added that Lancaster quotes the following remark, made by a resident for many years in the land, concerning Nubian eunuchs: "As far as I can judge, sex feeling exists unmodified by absence of the sexual organs. The eunuch differs from the man not in the absence of sexual passion, but only in the fact that he cannot fully gratify it. As far as he can approach a gratification of it he does so." In this connection it may be noted that (as quoted by Moll) Jaeger attributes the preference of some women—noted in ancient Rome and in the East—for castrated men as due not only to the freedom from risk of impregnation in such intercourse, but also to the longer duration of erection in the castrated.

When castration is performed without removal of the penis it is said that potency remains for at least ten years afterward, and Disselhorst, who in his Die accessorischen Geschlechtsdruesen der Wirbelthiere takes the same view as has been here adopted, mentions that, according to Pelikan (Das Skopzentum in Ruessland), those castrated at puberty are fit for coitus long afterward. When castration is performed for surgical reasons at a later age it is still less likely to affect potency or to change the sexual feelings. Guinard concludes that the sexual impulse after castration is relatively more persistent in man than in the lower animals, and is sometimes even heightened, being probably more dependent on external stimuli.

Except in the East, castration is more often performed on women than on men, and then the evidence as to the influence of the removal of the ovaries on the sexual emotions shows varying results. It has been found that after castration sexual desire and sexual pleasure in coitus may either remain the same, be diminished or extinguished, or be increased. By some the diminution has been attributed to autosuggestion, the woman being convinced that she can no longer be like other women; the augmentation of desire and pleasure has been supposed to be due to the removal of the dread of impregnation. We have, of course, to take into account individual peculiarities, method of life, and the state of the health.

The independence of the sexual impulse from the distention of the sexual glands is further indicated by the great frequency with which sexual sensations, in a faint or even strong degree, are experienced in childhood and sometimes in infancy, and by the fact that they often persist in women long after the sexual glands have ceased their functions.

Reference may finally be made to those cases in which the sexual impulse has developed notwithstanding the absence, verified or probable, of any sexual glands at all. In such cases sexual desire and sexual gratification are sometimes even stronger than normal. Colman has reported a case in which neither ovaries nor uterus could be detected, and the vagina was too small for coitus, but pleasurable intercourse took place by the rectum and sexual desire was at times so strong as to amount almost to nymphomania. Clara Barrus has reported the case of a woman in whom there was congenital absence of uterus and ovaries, as proved subsequently by autopsy, but the sexual impulse was very strong and she had had illicit intercourse with a lover. She suffered from recurrent mania, and then masturbated shamelessly; when sane she was attractively feminine. Macnaughton-Jones describes the case of a woman of 32 with normal sexual feelings and fully developed breasts, clitoris, and labia, but no vagina or internal genitalia could be detected even under the most thorough examination. In a case of Bridgman's, again, the womb and ovaries were absent, and the vagina small, but coitus was not painful, and the voluptuous sensations were complete and sexual passion was strong. In a case of Cotterill's, the ovaries and uterus were of minute size and functionless, and the vagina was absent, but the sexual feelings were normal, and the clitoris preserved its usual sensibility. Munde had recorded two similar cases, of which he presents photographs. In all these cases not only was the sexual impulse present in full degree, but the subjects were feminine in disposition and of normal womanly conformation; in most cases the external sexual organs were properly developed.

It will be seen that the question of the nature of the sexual impulse has been slowly transformed. It is no longer a question of the formation of semen in the male, of the function of menstruation in the female. It has become largely a question of physiological chemistry. The chief parts in the drama of sex, alike on its psychic as on its physical sides, are thus supposed to be played by two mysterious protagonists, the hormones, or internal secretions, of the testes and of the ovary. Even the part played by the brain is now often regarded as chemical, the brain being considered to be a great chemical laboratory. There is a tendency, moreover, to extend the sexual sphere so as to admit the influence of internal secretions from other glands. The thymus, the adrenals, the thyroid, the pituitary, even the kidneys: it is possible that internal secretions from all these glands may combine to fill in the complete picture of sexuality as we know it in men and women. The subject is, however, so complex and at present so little known that it would be hazardous, and for the present purpose it is needless, to attempt to set forth any conclusions.

It is sufficiently clear that there is on the surface a striking analogy between sexual desire and the impulse to evacuate an excretion, and that this analogy is not only seen in the frog, but extends also to the highest vertebrates. It is quite another matter, however, to assert that the sexual impulse can be adequately defined as an impulse to evacuate. To show fully the inadequate nature of this conception would require a detailed consideration of the facts of sexual life. That is, however, unnecessary. It is enough to point out certain considerations which alone suffice to invalidate this view. In the first place, it must be remarked that the trifling amount of fluid emitted in sexual intercourse is altogether out of proportion to the emotions aroused by the act and to its after-effect on the organism; the ancient dictum omne animal post coitum triste may not be exact, but it is certain that the effect of coitus on the organism is far more profound than that produced by the far more extensive evacuation of the bladder or bowels. Again, this definition leaves unexplained all those elaborate preliminaries which, both in man and the lower animals, precede the sexual act, preliminaries which in civilized human beings sometimes themselves constitute a partial satisfaction to the sexual impulse. It must also be observed that, unlike the ordinary excretions, this discharge of the sexual glands is not always, or in every person, necessary at all. Moreover, the theory of evacuation at once becomes hopelessly inadequate when we apply it to women; no one will venture to claim that an adequate psychological explanation of the sexual impulse in a woman is to be found in the desire to expel a little bland mucus from the minute glands of the genital tract. We must undoubtedly reject this view of the sexual impulse. It has a certain element of truth and it permits an instructive and helpful analogy; but that is all. The sexual act presents many characters which are absent in an ordinary act of evacuation, and, on the other hand, it lacks the special characteristic of the evacuation proper, the elimination of waste material; the seminal fluid is not a waste material, and its retention is, to some extent perhaps, rather an advantage than a disadvantage to the organism.

Eduard von Hartmann long since remarked that the satisfaction of what we call the sexual instinct through an act carried out with a person of the opposite sex is a very wonderful phenomenon. It cannot be said, however, that the conception of the sexual act as a simple process of evacuation does anything to explain the wonder. We are, at most, in the same position as regards the stilling of normal sexual desire as we should be as regards the emptying of the bladder, supposing it were very difficult for either sex to effect this satisfactorily without the aid of a portion of the body of a person of the other sex acting as a catheter. In such a case our thoughts and ideals would center around persons of opposite sex, and we should court their attention and help precisely as we do now in the case of our sexual needs. Some such relationship does actually exist in the case of the suckling mother and her infant. The mother is indebted to the child for the pleasurable relief of her distended breasts; and, while in civilization more subtle pleasures and intelligent reflection render this massive physical satisfaction comparatively unessential to the act of suckling, in more primitive conditions and among animals the need of this pleasurable physical satisfaction is a real bond between the mother and her offspring. The analogy is indeed very close: the erectile nipple corresponds to the erectile penis, the eager watery mouth of the infant to the moist and throbbing vagina, the vitally albuminous milk to the vitally albuminous semen. The complete mutual satisfaction, physical and psychic, of mother and child, in the transfer from one to the other of a precious organized fluid, is the one true physiological analogy to the relationship of a man and a woman at the climax of the sexual act. Even this close analogy, however, fails to cover all the facts of the sexual life.

A very different view is presented to us in the definition of the sexual instinct as a reproductive impulse, a desire for offspring. Hegar, Eulenburg, Naecke, and Loewenfeld have accepted this as, at all events, a partial definition. No one, indeed, would argue that it is a complete definition, although a few writers appear to have asserted that it is so sometimes as regards the sexual impulse in women. There is, however, considerable mental confusion in the attempt to set up such a definition. If we define an instinct as an action adapted to an end which is not present to consciousness, then it is quite true that the sexual instinct is an instinct of reproduction. But we do not adequately define the sexual instinct by merely stating its ultimate object. We might as well say that the impulse by which young animals seize food is "an instinct of nutrition." The object of reproduction certainly constitutes no part of the sexual impulse whatever in any animal apart from man, and it reveals a lack of the most elementary sense of biological continuity to assert that in man so fundamental and involuntary a process can suddenly be revolutionized. That the sexual impulse is very often associated with a strong desire for offspring there can be no doubt, and in women the longing for a child—that is to say, the longing to fulfill those functions for which their bodies are constituted—may become so urgent and imperative that we may regard it as scarcely less imperative than the sexual impulse. But it is not the sexual impulse, though intimately associated with it, and though it explains it. A reproductive instinct might be found in parthenogenetic animals, but would be meaningless, because useless, in organisms propagating by sexual union. A woman may not want a lover, but may yet want a child. This merely means that her maternal instincts have been aroused, while her sexual instincts are still latent. A desire for reproduction, as soon as that desire becomes instinctive, necessarily takes on the form of the sexual impulse, for there is no other instinctive mechanism by which it can possibly express itself. A "reproductive instinct," apart from the sexual instinct and apart from the maternal instinct, cannot be admitted; it would be an absurdity. Even in women in whom the maternal instincts are strong, it may generally be observed that, although before a woman is in love, and also during the later stages of her love, the conscious desire for a child may be strong, during the time when sexual passion is at its highest the thought of offspring, under normally happy conditions, tends to recede into the background. Reproduction is the natural end and object of the sexual instinct, but the statement that it is part of the contents of the sexual impulse, or can in any way be used to define that impulse, must be dismissed as altogether inacceptable. Indeed, although the term "reproductive instinct" is frequently used, it is seldom used in a sense that we need take seriously; it is vaguely employed as a euphemism by those who wish to veil the facts of the sexual life; it is more precisely employed mainly by those who are unconsciously dominated by a superstitious repugnance to sex.

I now turn to a very much more serious and elaborate attempt to define the constitution of the sexual impulse, that of Moll. He finds that it is made up of two separate components, each of which may be looked upon as an uncontrollable impulse. One of these is that by which the tension of the sexual organs is spasmodically relieved; this he calls the impulse of detumescence, and he regards it as primary, resembling the impulse to empty a full bladder. The other impulse is the "instinct to approach, touch, and kiss another person, usually of the opposite sex"; this he terms the impulse of contrectation, and he includes under this head not only the tendency to general physical contact, but also the psychic inclination to become generally interested in a person of the opposite sex. Each of these primary impulses Moll regards as forming a constituent of the sexual instinct in both men and women. It seems to me undoubtedly true that these two impulses do correspond to the essential phenomena. The awkward and unsatisfactory part of Moll's analysis is the relation of the one to the other. It is true that he traces both impulses back to the sexual glands, that of detumescence directly, that of contrectation indirectly; but evidently he does not regard them as intimately related to each other; he insists on the fact that they may exist apart from each other, that they do not appear synchronously in youth: the contrectation impulse he regards as secondary; it is, he states, an indirect result of the sexual glands, "only to be understood by the developmental history of these glands and the object which they subserve"; that is to say, that it is connected with the rise of the sexual method of reproduction and the desirability of the mingling of the two sexes in procreation, while the impulse of detumescence arose before the sexual method of reproduction had appeared; thus the contrectation impulse was propagated by natural selection together with the sexual method of reproduction. The impulse of contrectation is secondary, and Moll even regards it as a secondary sexual character.

While, therefore, this analysis seems to include all the phenomena and to be worthy of very careful study as a serious and elaborate attempt to present an adequate psychological definition of the sexual impulse, it scarcely seems to me that we can accept it in precisely the form in which Moll presents it. I believe, however, that by analyzing the process a little more minutely we shall find that these two constituents of the sexual impulse are really much more intimately associated than at the first glance appears, and that we need by no means go back to the time when the sexual method of reproduction arose to explain the significance of the phenomena which Moll includes under the term contrectation.

To discover the true significance of the phenomena in men it is necessary to observe carefully the phenomena of love-making not only among men, but among animals, in which the impulse of contrectation plays a very large part, and involves an enormous expenditure of energy. Darwin was the first to present a comprehensive view of, at all events a certain group of, the phenomena of contrectation in animals; on his interpretation of those phenomena he founded his famous theory of sexual selection. We are not primarily concerned with that theory; but the facts on which Darwin based his theory lie at the very roots of our subject, and we are bound to consider their psychological significance. In the first place, since these phenomena are specially associated with Darwin's name, it may not be out of place to ask what Darwin himself considered to be their psychological significance. It is a somewhat important question, even for those who are mainly concerned with the validity of the theory which Darwin established on those facts, but so far as I know it has not hitherto been asked. I find that a careful perusal of the Descent of Man reveals the presence in Darwin's mind of two quite distinct theories, neither of them fully developed, as to the psychological meaning of the facts he was collecting. The two following groups of extracts will serve to show this very conclusively: "The lower animals have a sense of beauty," he declares, "powers of discrimination and taste on the part of the female" (p. 211 ); "the females habitually or occasionally prefer the more beautiful males," "there is little improbability in the females of insects appreciating beauty in form or color" (p. 329); he speaks of birds as the most "esthetic" of all animals excepting man, and adds that they have "nearly the same taste for the beautiful as we have" (p. 359); he remarks that a change of any kind in the structure or color of the male bird "appears to have been admired by the female" (p. 385). He speaks of the female Argus pheasant as possessing "this almost human degree of taste." Birds, again, "seem to have some taste for the beautiful both in color and sound," and "we ought not to feel too sure that the female does not attend to each detail of beauty" (p. 421). Novelty, he says, is "admired by birds for its own sake" (p. 495). "Birds have fine powers of discrimination and in some few instances it can be shown that they have a taste for the beautiful" (p. 496). The "esthetic capacity" of female animals has been advanced by exercise just as our own taste has improved (p. 616). On the other hand, we find running throughout the book quite another idea. Of cicadas he tells us that it is probable that, "like female birds, they are excited or allured by the male with the most attractive voice" (p. 282); and, coming to Locustidae, he states that "all observers agree that the sounds serve either to call or excite the mute females" (p. 283). Of birds he says, "I am led to believe that the females prefer or are most excited by the more brilliant males" (p. 316). Among birds also the males "endeavor to charm or excite their mates by love-notes," etc., and "the females are excited by certain males, and thus unconsciously prefer them" (p. 367), while ornaments of all kinds "apparently serve to excite, attract, or fascinate the female" (p. 394). In a supplemental note, also, written in 1876, five years after the first publication of the Descent of Man, and therefore a late statement of his views, Darwin remarks that "no supporter of the principle of sexual selection believes that the females select particular points of beauty in the males; they are merely excited or attracted in a greater degree by one male than by another, and this seems often to depend, especially with birds, on brilliant coloring" (p. 623). Thus, on the one hand, Darwin interprets the phenomena as involving a real esthetic element, a taste for the beautiful; on the other hand, he states, without apparently any clear perception that the two views are quite distinct, that the colors and sounds and other characteristics of the male are not an appeal to any esthetic sense of the female, but an appeal to her sexual emotions, a stimulus to sexual excitement, an allurement to sexual contact. According to the first theory, the female admires beauty, consciously or unconsciously, and selects the most beautiful partner ; according to the second theory, there is no esthetic question involved, but the female is unconsciously influenced by the most powerful or complex organic stimulus to which she is subjected. There can be no question that it is the second, and not the first, of these two views which we are justified in accepting. Darwin, it must be remembered, was not a psychologist, and he lived before the methods of comparative psychology had begun to be developed; had he written twenty years later we may be sure he would never have used so incautiously some of the vague and hazardous expressions I have quoted. He certainly injured his theory of sexual selection by stating it in too anthropomorphic language, by insisting on "choice," "preference," "esthetic sense," etc. There is no need whatever to burden any statement of the actual facts by such terms borrowed from human psychology. The female responds to the stimulation of the male at the right moment just as the tree responds to the stimulation of the warmest days in spring. We should but obscure this fact by stating that the tree "chooses" the most beautiful days on which to put forth its young sprouts. In explaining the correlation between responsive females and accomplished males the supposition of esthetic choice is equally unnecessary. It is, however, interesting to observe that, though Darwin failed to see that the love-combats, pursuits, dances, and parades of the males served as a method of stimulating the impulse of contrectation—or, as it would be better to term it, tumescence—in the male himself, he to some extent realized the part thus played in exciting the equally necessary activity of tumescence in the female.

Wallace opposed Darwin's theory of sexual selection, but it can scarcely be said that his attitude toward it bears critical examination. On the one hand, as has already been noted, he saw but one side of that theory and that the unessential side, and, on the other hand, his own view really coincided with the more essential elements in Darwin's theory. In his Tropical Nature he admitted that the male's "persistency and energy win the day," and also that this "vigor and liveliness" of the male are usually associated with intense coloration, while twenty years later (in his Darwinism) he admitted also that it is highly probable that the female is pleased or excited by the male's display. But all that is really essential in Darwin's theory is involved, directly or indirectly, in these admissions.

Espinas, in 1878, in his suggestive book, Des Societes Animales, described the odors, colors and forms, sounds, games, parades, and mock battles of animals, approaching the subject in a somewhat more psychological spirit than either Darwin or Wallace, and he somewhat more clearly apprehended the object of these phenomena in producing mutual excitement and stimulating tumescence. He noted the significance of the action of the hermaphroditic snails in inserting their darts into each other's flesh near the vulva in order to cause preliminary excitation. He remarks of this whole group of phenomena: "It is the preliminary of sexual union, it constitutes the first act of it. By it the image of the male is graven on the consciousness of the female, and in a manner impregnates it, so as to determine there, as the effects of this representation descend to the depths of the organism, the physiological modifications necessary to fecundation." Beaunis, again, in an analysis of the sexual sensations, was inclined to think that the dances and parades of the male are solely intended to excite the female, not perceiving, however, that they at the same time serve to further excite the male also.

A better and more comprehensive statement was reached by Tillier, who, to some extent, may be said to have anticipated Groos. Darwin, Tillier pointed out, had not sufficiently taken into account the coexistence of combat and courtship, nor the order of the phenomena. Courtship without combat, Tillier argued, is rare; "there is a normal coexistence of combat and courtship." Moreover, he proceeded, force is the chief factor in determining the possession of the female by the male, who in some species is even prepared to exert force on her; so that the female has little opportunity of sexual selection, though she is always present at these combats. He then emphasized the significant fact that courtship takes place long after pairing has ceased, and the question of selection thus been eliminated. The object of courtship, he concluded, is not sexual selection by the female, but the sexual excitement of both male and female, such excitement, he asserted, not only rendering coupling easier, but favoring fecundation. Modesty, also, Tillier further argued, again anticipating Groos, works toward the same end; it renders the male more ardent, and by retarding coupling may also increase the secretions of the sexual glands and favor the chances of reproduction.

The psychological significance of these facts has been carefully studied and admirably developed by Groos in his classic works on the play instinct in animals and in men. Going beyond Wallace, Groos denies conscious sexual selection, but, as he points out, this by no means involves the denial of unconscious selection in the sense that "the female is most easily won by the male who most strongly excites her sexual instincts." Groos further quotes a pregnant generalization of Ziegler: "In all animals a high degree of excitement of the nervous system is necessary to procreation, and thus we find an excited prelude to procreation widely spread." Such a stage, indeed, as Groos points out, is usually necessary before any markedly passionate discharge of motor energy, as may be observed in angry dogs and the Homeric heroes. While, however, in other motor explosions the prelude may be reduced to a minimum, in courtship it is found in a highly marked degree. The primary object of courtship, Groos insists, is to produce sexual excitement.

It is true that Groos's main propositions were by no means novel. Thus, as I have pointed out, he was at most points anticipated by Tillier. But Groos developed the argument in so masterly a manner, and with so many wide-ranging illustrations, that he has carried conviction where the mere insight of others had passed unperceived. Since Darwin wrote the Descent of Man the chief step in the development of the theory of sexual selection has been taken by Groos, who has at the same time made it clear that sexual selection is largely a special case of natural selection. The conjunction of the sexes is seen to be an end only to be obtained with much struggle; the difficulty of achieving sexual erethism in both sexes, the difficulty of so stimulating such erethism in the female that her instinctive coyness is overcome, these difficulties the best and most vigorous males, those most adapted in other respects to carry on the race, may most easily overcome. In this connection we may note what Marro has said in another connection, when attempting to answer the question why it is that among savages courtship becomes so often a matter in which persuasion takes the form of force. The explanation, he remarks, is yet very simple. Force is the foundation of virility, and its psychic manifestation is courage. In the struggle for life violence is the first virtue. The modesty of women—in its primordial form consisting in physical resistance, active or passive, to the assaults of the male—aided selection by putting to the test man's most important quality, force. Thus it is that when choosing among rivals for her favors a woman attributes value to violence. Marro thus independently confirms the result reached by Groos.

The debate which has for so many years been proceeding concerning the validity of the theory of sexual selection may now be said to be brought to an end. Those who supported Darwin and those who opposed him were, both alike, in part right and in part wrong, and it is now possible to combine the elements of truth on either side into a coherent whole. This is now beginning to be widely recognized; Lloyd Morgan, for instance, has readjusted his position as regards the "pairing instinct" in the light of Groos's contribution to the subject. "The hypothesis of sexual selection," he concludes, "suggests that the accepted male is the one which adequately evokes the pairing impulse. … Courtship may thus be regarded from the physiological point of view as a means of producing the requisite amount of pairing hunger; of stimulating the whole system and facilitating general and special vascular changes; of creating that state of profound and explosive irritability which has for its psychological concomitant or antecedent an imperious and irresistible craving. … Courtship is thus the strong and steady bending of the bow that the arrow may find its mark in a biological end of the highest importance in the survival of a healthy and vigorous race."

If, in the light of the previous discussion, we examine such facts as those here collected, we may easily trace throughout the perpetual operations of the same instinct. It is everywhere the instinctive object of the male, who is very rarely passive in the process of courtship, to assure by his activity in display, his energy or skill or beauty, both his own passion and the passion of the female. Throughout nature sexual conjugation only takes place after much expenditure of energy. We are deceived by what we see among highly fed domesticated animals, and among the lazy classes of human society, whose sexual instincts are at once both unnaturally stimulated and unnaturally repressed, when we imagine that the instinct of detumescence is normally ever craving to be satisfied, and that throughout nature it can always be set off at a touch whenever the stimulus is applied. So far from the instinct of tumescence naturally needing to be crushed, it needs, on the contrary, in either sex to be submitted to the most elaborate and prolonged processes in order to bring about those conditions which detumescence relieves. A state of tumescence is not normally constant, and tumescence must be obtained before detumescence is possible. The whole object of courtship, of the mutual approximation and caresses of two persons of the opposite sex, is to create the state of sexual tumescence.

It will be seen that the most usual method of attaining tumescence—a method found among the most various kinds of animals, from insects and birds to man—is some form of the dance. Among the Negritos of the Philippines dancing is described by A.B. Meyer as "jumping in a circle around a girl and stamping with the feet"; as we have seen, such a dance is, essentially, a form of courtship that is widespread among animals. "The true cake-walk," again, Stanley Hall remarks, "as seen in the South is perhaps the purest expression of this impulse to courtship antics seen in man." Muscular movement of which the dance is the highest and most complex expression, is undoubtedly a method of auto-intoxication of the very greatest potency. All energetic movement, indeed, tends to produce active congestion. In its influence on the brain violent exercise may thus result in a state of intoxication even resembling insanity. As Lagrange remarks, the visible effects of exercise—heightened color, bright eyes, resolute air and walk—are those of slight intoxication, and a girl who has waltzed for a quarter of an hour is in the same condition as if she had drunk champagne. Groos regards the dance as, above all, an intoxicating play of movement, possessing, like other methods of intoxication,—and even apart from its relationship to combat and love,—the charm of being able to draw us out of our everyday life and lead us into a self-created dream-world. That the dance is not only a narcotic, but also a powerful stimulant, we may clearly realize from the experiments which show that this effect is produced even by much less complex kinds of muscular movement. This has been clearly determined, for instance, by Fere, in the course of a long and elaborate series of experiments dealing with the various influences that modify work as measured by Mosso's ergograph. This investigator found that muscular movement is the most efficacious of all stimulants in increasing muscular power. It is easy to trace these pleasurable effects of combined narcotic and stimulant motion in everyday life and it is unnecessary to enumerate its manifestations.

Dancing, as the highest and most complex form of muscular movement, is the most potent method of obtaining the organic excitement muscular movement yields, and thus we understand how from the earliest zooelogical ages it has been brought to the service of the sexual instinct as a mode of attaining tumescence. Among savages this use of dancing works harmoniously with the various other uses which dancing possesses in primitive times and which cause it to occupy so large and vital a part in savage life that it may possibly even affect the organism to such an extent as to mold the bones; so that some authorities have associated platycnemia with dancing. As civilization advances, the other uses of dancing fall away, but it still remains a sexual stimulant. Burton, in his Anatomy of Melancholy, brings forward a number of quotations from old authors showing that dancing is an incitement to love.

In civilization, however, dancing is not only an incitement to love and a preliminary to courtship, but it is often a substitute for the normal gratification of the sexual instinct, procuring something of the pleasure and relief of gratified love. In occasional abnormal cases this may be consciously realized. Thus Sadger, who regards the joy of dancing as a manifestation of "muscular eroticism," gives the case of a married hysterical woman of 21, with genital anesthesia, but otherwise strongly developed skin eroticism, who was a passionate dancer: "I often felt as though I was giving myself to my partner in dancing," she said, "and was actually having coitus with him. I have the feeling that in me dancing takes the place of coitus." Normally something of the same feeling is experienced by many young women, who will expend a prodigious amount of energy in dancing, thus procuring, not fatigue, but happiness and relief. It is significant that, after sexual relations have begun, girls generally lose much of their ardor in dancing. Even our modern dances, it is worthy of note, are often of sexual origin; thus, the most typical of all, the waltz, was originally (as Schaller, quoted by Groos, states) the close of a complicated dance which "represented the romance of love, the seeking and the fleeing, the playful sulking and shunning, and finally the jubilation of the wedding."

Not only is movement itself a source of tumescence, but even the spectacle of movement tends to produce the same effect. The pleasure of witnessing movement, as represented by its stimulating effect on the muscular system,—for states of well-being are accompanied by an increase of power,—has been found susceptible of exact measurement by Fere. He has shown that to watch a colored disk when in motion produced stronger muscular contractions, as measured by the dynamometer, than to watch the same disk when motionless. Even in the absence of color a similar influence of movement was noted, and watching a modified metronome produced a greater increase of work with the ergograph than when working to the rhythm of the metronome without watching it. This psychological fact has been independently discovered by advertisers, who seek to impress the value of their wares on the public by the device of announcing them by moving colored lights. The pleasure given by the ballet largely depends on the same fact. Not only is dancing an excitation, but the spectacle of dancing is itself exciting, and even among savages dances have a public which becomes almost as passionately excited as the dancers themselves. It is in virtue of this effect of dancing and similar movements that we so frequently find, both among the lower animals and savage man, that to obtain tumescence in both sexes, it is sufficient for one sex alone, usually the male, to take the active part. This point attracted the attention of Kulischer many years ago, and he showed how the dances of the men, among savages, excite the women, who watch them intently though unobtrusively, and are thus influenced in choosing their lovers. He was probably the first to insist that in man sexual selection has taken place mainly through the agency of dances, games, and festivals.

It is now clear, therefore, why the evacuation theory of the sexual impulse must necessarily be partial and inadequate. It leaves out of account the whole of the phenomena connected with tumescence, and those phenomena constitute the most prolonged, the most important, the most significant stage of the sexual process. It is during tumescence that the whole psychology of the sexual impulse is built up; it is as an incident arising during tumescence and influencing its course that we must probably regard nearly every sexual aberration. It is with the second stage of the sexual process, when the instinct of detumescence arises, that the analogy of evacuation can alone be called in. Even here, that analogy, though real, is not complete, the nervous element involved in detumescence being out of all proportion to the extent of the evacuation. The typical act of evacuation, however, is a nervous process, and when we bear this in mind we may see whatever truth the evacuation theory possesses. Beaunis classes the sexual impulse with the "needs of activity," but under this head he coordinates it with the "need of urination." That is to say, that both alike are nervous explosions. Micturition, like detumescence, is a convulsive act, and, like detumescence also, it is certainly connected with cerebral processes; thus in epilepsy the passage of urine which may occur (as in a girl described by Gowers with minor attacks during which it was emitted consciously, but involuntarily) is really a part of the process.

There appears, indeed, to be a special and intimate connection between the explosion of sexual detumescence and the explosive energy of the bladder; so that they may reinforce each other and to a limited extent act vicariously in relieving each other's tension. It is noteworthy that nocturnal and diurnal incontinence of urine, as well as "stammering" of the bladder, are all specially liable to begin or to cease at puberty. In men and even infants, distention of the bladder favors tumescence by producing venous congestion, though at the same time it acts as a physical hindrance to sexual detumescence ; in women—probably not from pressure alone, but from reflex nervous action—a full bladder increases both sexual excitement and pleasure, and I have been informed by several women that they have independently discovered this fact for themselves and acted in accordance with it. Conversely, sexual excitement increases the explosive force of the bladder, the desire to urinate is aroused, and in women the sexual orgasm, when very acute and occurring with a full bladder, is occasionally accompanied, alike in savage and civilized life, by an involuntary and sometimes full and forcible expulsion of urine. The desire to urinate may possibly be, as has been said, the normal accompaniment of sexual excitement in women (just as it is said to be in mares; so that the Arabs judge that the mare is ready for the stallion when she urinates immediately on hearing him neigh). The association may even form the basis of sexual obsessions. I have elsewhere shown that, of all the influences which increase the expulsive force of the bladder, sexual excitement is the most powerful. It may also have a reverse influence and inhibit contraction of the bladder, sometimes in association with shyness, but also independently of shyness. There is also reason to suppose that the nervous energy expended in an explosion of the tension of the sexual organs may sometimes relieve the bladder; it is well recognized that a full bladder is a factor in producing sexual emissions during sleep, the explosive energy of the bladder being inhibited and passing over into the sexual sphere. Conversely, it appears that explosion of the bladder relieves sexual tension. An explosion of the nervous centers connected with the contraction of the bladder will relieve nervous tension generally; there are forms of epilepsy in which the act of urination constitutes the climax, and Gowers, in dealing with minor epilepsy, emphasizes the frequency of micturition, which "may occur with spasmodic energy when there is only the slightest general stiffness," especially in women. He adds the significant remark that it "sometimes seems to relieve the cerebral tension," and gives the case of a girl in whom the aura consisted mainly of a desire to urinate; if she could satisfy this the fit was arrested; if not she lost consciousness and a severe fit followed.

If micturition may thus relieve nervous tension generally, it is not surprising that it should relieve the tension of the centers with which it is most intimately connected. Serieux records the case of a girl of 12, possessed by an impulse to masturbation which she was unable to control, although anxious to conquer it, who only found relief in the act of urination; this soothed her and to some extent satisfied the sexual excitement; when the impulse to masturbate was restrained the impulse to urinate became imperative; she would rise four or five times in the night for this purpose, and even urinate in bed or in her clothes to obtain the desired sexual relief. I am acquainted with a lady who had a similar, but less intense, experience during childhood. Sometimes, especially in children, the act of urination becomes an act of gratification at the climax of sexual pleasure, the imitative symbol of detumescence. Thus Schultze-Malkowsky describes a little girl of 7 who would bribe her girl companions with little presents to play the part of horses on all fours while she would ride on their necks with naked thighs in order to obtain the pleasurable sensation of close contact. With one special friend she would ride facing backward, and leaning forward to embrace her body impulsively, and at the same time pressing the neck closely between her thighs, would urinate. Fere has recorded the interesting case of a man who, having all his life after puberty been subject to monthly attacks of sexual excitement, after the age of 45 completely lost the liability to these manifestations, but found himself subject, in place of them, to monthly attacks of frequent and copious urination, accompanied by sexual day-dreams, but by no genital excitement. Such a case admirably illustrates the compensatory relation of sexual and vesical excitation. This mutual interaction is easily comprehensible when we recall the very close nervous connection which exists between the mechanisms of the sexual organs and the bladder.

Nor are such relationships found to be confined to these two centers; in a lesser degree the more remote explosive centers are also affected; all motor influences may spread to related muscles; the convulsion of laughter, for instance, seems to be often in relation with the sexual center, and Groos has suggested that the laughter which, especially in the sexually minded, often follows allusions to the genital sphere is merely an effort to dispel nascent sexual excitement by liberating an explosion of nervous energy in another direction. Nervous discharges tend to spread, or to act vicariously, because the motor centers are more or less connected. Of all the physiological motor explosions, the sexual orgasm, or detumescence, is the most massive, powerful, and overwhelming. So volcanic is it that to the ancient Greek philosophers it seemed to be a minor kind of epilepsy. The relief of detumescence is not merely the relief of an evacuation; it is the discharge, by the most powerful apparatus for nervous explosion in the body, of the energy accumulated and stored up in the slow process of tumescence, and that discharge reverberates through all the nervous centers in the organism.

It seems unprofitable at present to attempt any more fundamental analysis of the sexual impulse. Beaunis, in the work already quoted, vaguely suggests that we ought possibly to connect the sexual excitation which leads the male to seek the female with chemical action, either exercised directly on the protoplasm of the organism or indirectly by the intermediary of the nervous system, and especially by smell in the higher animals. Clevenger, Spitzka, Kiernan, and others have also regarded the sexual impulse as protoplasmic hunger, tracing it back to the presexual times when one protozoal form absorbed another. In the same way Joanny Roux, insisting that the sexual need is a need of the whole organism, and that "we love with the whole of our body," compares the sexual instinct to hunger, and distinguishes between "sexual hunger" affecting the whole system and "sexual appetite" as a more localized desire; he concludes that the sexual need is an aspect of the nutritive need. Useful as these views are as a protest against too crude and narrow a conception of the part played by the sexual impulse, they carry us into a speculative region where proof is difficult.

We are now, however, at all events, in a better position to define the contents of the sexual impulse. We see that there are certainly, as Moll has indicated, two constituents in that impulse; but, instead of being unrelated, or only distantly related, we see that they are really so intimately connected as to form two distinct stages in the same process: a first stage, in which—usually under the parallel influence of internal and external stimuli—images, desires, and ideals grow up within the mind, while the organism generally is charged with energy and the sexual apparatus congested with blood; and a second stage, in which the sexual apparatus is discharged amid profound sexual excitement, followed by deep organic relief. By the first process is constituted the tension which the second process relieves. It seems best to call the first impulse the process of tumescence; the second the process of detumescence. The first, taking on usually a more active form in the male, has the double object of bringing the male himself into the condition in which discharge becomes imperative, and at the same time arousing in the female a similar ardent state of emotional excitement and sexual turgescence. The second process has the object, directly, of discharging the tension thus produced and, indirectly, of effecting the act by which the race is propagated.

It seems to me that this is at present the most satisfactory way in which we can attempt to define the sexual impulse.

Original footnotes
The more carefully animals are observed, the more often this is found to be the case, even with respect to species which possess no obvious and elaborate process for obtaining tumescence. See, for instance, the detailed and very instructive account—too long to quote here—given by E. Selous of the preliminaries to intercourse practised by a pair of great crested grebes, while nest-building. Intercourse only took place with much difficulty, after many fruitless invitations, more usually given by the female. ("Observational Diary of the Habits of the Great Crested Grebe," Zoeologist, September, 1901.) It is exactly the same with savages. The observation of Foley (Bulletin de la Societe d'Anthropologie de Paris, November 6, 1879) that in savages "sexual erethism is very difficult" is of great significance and certainly in accordance with the facts. This difficulty of erethism is the real cause of many savage practices which to the civilized person often seem perverse; the women of the Caroline Islands, for instance, as described by Finsch, require the tongue or even the teeth to be applied to the clitoris, or a great ant to be applied to bite the parts, in order to stimulate orgasm. Westermarck, after quoting a remark of Mariner's concerning the women of Tonga,—"it must not be supposed that these women are always easily won; the greatest attentions and the most fervent solicitations are sometimes requisite, even though there be no other lover in the way,"—adds that these words "hold true for a great many, not to say all, savage and barbarous races now existing." (Human Marriage, p. 163.) The old notions, however, as to the sexual licentiousness of peoples living in natural conditions have scarcely yet disappeared. See Appendix A; "The Sexual Instinct in Savages."