The moods of love, like the more stereotyped manifestations of sex, are dependent upon a proper supply to the blood of the internal secretions of the reproductive organs, the gonadal endocrines. If the testes are removed from frogs, it is found that the clasp-reflex, symptom of sex desire, is abolished. If, after an interval of several days, the testes' extract is injected into the frog, the reflex reappears for a few days. The hormone provoking this sex reflex is present in the testes only during the breeding season. In birds, the seasonal nesting and migrating instincts may be eliminated by interfering with their ovaries. At the same tine there is a change in their plumage toward the male type. Similarly, the males, when their sex endocrines are cut off, will change their psychic nature as well as physically. Besides owning his flag-waving comb, his spurs and brighter feathers, the rooster struts to attract the female, and fights aggressively with his sex competitors. When he is made a capon, he loses his spurs and comb and distinctive plumage, and in addition becomes retiring and submissive, in short, a pseudo-hen in his instincts as well as in appearance. If the genital glands are extirpated from a male before puberty, the wattles remain small, pale and bloodless, no active, amorous or combative instinct emerges. The creature maintains a demure silence, and may even be sought by a virile male. So we may see homosexuality of a kind in the lowest animals. On the other hand, hens deprived of ovaries tend to metamorphose in the male direction, even to acquire the male spurs, and to display the male attitudes.
All through the animal world, in the springtime, when the pituitary awakens or increases its secretion, and so stimulates the sex glands to augmented activity, emotions of sex and their expression are provoked by the inner stirring. When the nightingale warbles passionately and the mocking bird gurgles provokingly, when the robin fills its scarlet breast and the starling floats in ecstasy through the perfumed air, when the pigeon coyly woos its mate, and the butterfly flirts with the dazzling multicolors of its wings, when all the marvelous devices of sex attraction in nature, selection and courting, mating and reproducing are pondered, who but must wonder at the infinite possibilities of reaction of the sex hormones? All is for love, and all is because of the love in the blood that is manufactured unconsciously by a few hidden cells.
EXPRESSIONISM AND EXHIBITIONISM
We need a detailed examination of the various forms of expression art has differentiated into, in its relation to exhibitionism and as effects of the circulating libido-producing substance of the gonads. Sex exhibition differs in man and woman because of the differently combined internal secretions that are their substrates. The male's attitude, aggressive pursuit, is instigated by the compound adrenal and gonad endocrines. The female's various emulsions of coyness and display are motivated by posterior pituitary and gonad hormones in alliance.
It is a dogma to state that the internal secretions of sex do not begin to function until after puberty. Some children manifest exhibitionism with a certain independence of environment. Before adolescence a good many girls act like tom-boys, and are distinguishable externally from boys only by their clothes. But others display signs of sex differentiation that are to be traced back to an awakening interstitial gonad action. Some boys have no interest whatever in sex. Others will show an intense curiosity spontaneously, a curiosity which perhaps may be explained as a larval precocity, dependent upon the minimum of sex hormone production by the gonads. Close observation of the correlation of somatic and psychic development in extreme examples of these children corroborates this view. Jonathan Hutchinson has described full-busted children of London already boasting of their affairs. Indeed, as education and environment affect the body (in so far as they influence it as a whole) by exciting or inhibiting the glands of internal secretion, sex-arousing stimuli from without must be considered to evoke their effects as stimulants of the latent puberty glands.
At puberty, when the sex glands bloom, and the complex of the sex instincts is activated, exhibitionism manifests itself in a host of guises and disguises. Femininity in a woman, the womanly woman, or the eternal feminine, may indeed be defined by the degree of somatic and psychic exhibitionism she presents. A woman who has a delicate skin, lovely complexion, well-formed breasts and menstruates freely will be found to have the typical feminine outlook on life, aspirations and reactions to stimuli, which, in spite of the protests of our feminists, do constitute the biologic feminine mind. Large, vascular, balanced ovaries are the well-springs of her life and personality. On the other hand, the woman who menstruates poorly or not at all is coarse-featured, flat-breasted, heavily built, angular in her outlines, will also be often aggressive, dominating, even enterprising and pioneering, in short, masculinoid. She is what she is because she possesses small, shrivelled, poorly functioning ovaries. Between these two types all sorts of transitions exist, according as the other endocrines participate in the constitutional make-up. But no better examples could be given, off-hand, of the determining stamp of the internal secretions upon mind, character and conduct.
INSTINCT AND BEHAVIOUR
The sex instinct, analyzed as an endocrine mechanism, provides the clue to the understanding of all instinct and behaviour. If the post-pituitary regulates the maternal instinct, then its correlates: sympathy, social impulses, and religious feeling, must be also influenced, and so is furnished another example of a chemical control of instinctive behaviour. McDougall, once of Oxford, now of Harvard, introduced into psychology the idea of the simple instinct as a unit of behaviour, regarding the most complex conduct as a compounding of instincts. The instinct itself he analyzed into three elements: a specific stimulus-sensation, an emotion following, all ending in a particular course of muscular reaction. Translated into endocrine terms, what happens may be pictured as a series of chemical events.
When the activity of a ductless gland rises above a certain minimum, its hormones in the blood sensitize, as a photographic plate is sensitized, a group of brain cells, to respond to a message from the outside world, with a definite line of conduct. There is a registration by the brain cells of the presence of the specific stimulus. Then there is communication by them with the endocrine organs. As a result, some of them are moved to further secretion, and others are paralyzed or weakened. In consequence of changes of concentration in the blood of the various internal secretions, tensions, movements and tumescences, as well as relaxations, inhibitions and detumescences, occur throughout the vegetative system—the blood vessels, the viscera, the nerves and the muscles. Each wires to the brain news of the change in it. In addition, the brain cells themselves are excited or depressed by the new hormones bathing them. In their final fusion, the commingling vegetative sensations constitute the emotion evolved in the functioning of the instinct.
To lower the new tensions throughout the vegetative system to the normal range, the instinctive action is carried out. This superficially is regarded as the essence of the instinct. As a matter of fact, it is only the endpoint of a process, the resultant of a drive to restore equilibrium within the organism. It may all happen in less time than it takes to tell about it.