In the _Arabian Nights_ there are many allusions to the use of perfumes by women with a more or less definitely stated aphrodisiacal intent. Thus we read in the story of Kamaralzaman: "With fine incense I will perfume my breasts, my belly, my whole body, so that my skin may melt more sweetly in thy mouth, O apple of my eye!"
Even among savages the perfuming of the body is sometimes practiced with the object of inducing love in the partner. Schellong states that the Papuans of Kaiser Wilhelm's Land rub various fragrant plants into their bodies for this purpose. (_Zeitschrift für Ethnologie_, 1899, ht. i, p. 19.) The significance of this practice is more fully revealed by Haddon when studying the Papuans of Torres Straits among whom the initiative in courtship is taken by the women. It was by scenting himself with a pungent odorous substance that a young man indicated that he was ready to be sued by the girls. A man would wear this scent at the back of his neck during a dance in order to attract the attention of a particular girl; it was believed to act with magical certainty, after the manner of a charm (_Reports of the Cambridge Anthropological Expedition to Torres Straits_, vol. v, pp. 211, 222, and 328).
The perfume which is of all perfumes the most interesting from the present point of view is certainly musk. With ambergris, musk is the chief member of Linnæus's group of _Odores ambrosiacæ_, a group which in sexual significances, as Zwaardemaker remarks, ranks besides the capryl group of odors. It is a perfume of ancient origin; its name is Persian[59] (indicating doubtless the channel whence it reached Europe) and ultimately derived from the Sanskrit word for testicle in allusion to the fact that it was contained in a pouch removed from the sexual parts of the male musk-deer. Musk odors, however, often of considerable strength, are very widely distributed in Nature, alike among animals and plants. This is indicated by the frequency with which the word "musk" forms part of the names of animals and plants which are by no means always nearly related. We have the musk-ox, the musky mole, several species called musk-rat, the musk-duct, the musk-beetle; while among plants which have received their names from a real or supposed musky odor are, besides several that are called musk-plant, the musk-rose, the musk-hyacinth, the musk-mallow, the musk-orchid, the musk-melon, the musk-cherry, the musk-pear, the musk-plum, muskat and muscatels, musk-seed, musk-tree, musk-wood, etc.[60] But a musky odor is not merely widespread in Nature among plants and the lower animals, it is peculiarly associated with man. Incidentally we have already seen how it is regarded as characteristic of some races of man, especially the Chinese. Moreover, the smell of the negress is said to be musky in character, and among Europeans a musky odor is said to be characteristic of blondes. Laycock, in his _Nervous Diseases of Women_, stated his opinion that "the musk odor is certainly the sexual odor of man"; and Féré states that the musk odor is that among natural perfumes most nearly approaching the odor of the sexual secretions. We have seen that the Chinese poet vaunts the musky odor of his mistress's armpits, while another Oriental saying concerning the attractive woman is that "her navel is filled with musk." Persian literature contains many references to musk as an attractive body odor, and Firdusi speaks of a woman's hair as "a crown of musk," while the Arabian poet Motannabi says of his mistress that "her hyacinthine hair smells sweeter than Scythian musk." Galopin stated that he knew women whose natural odor of musk (and less frequently of ambergris) was sufficiently strong to impart to a bath in less than an hour a perfume due entirely to the exhalations of the musky body; it must be added that Galopin was an enthusiast in this matter.
The special significance of musk from our present point of view lies not only in the fact that we here have a perfume, widely scattered throughout nature and often in an agreeable form, which is at the same time a very frequent personal odor in man. Musk is the odor which not only in the animals to which it has given a name, but in many others, is a specifically sexual odor, chiefly emitted during the sexual season. The sexual odors, indeed, of most animals seem to be modifications of musk. The Sphinx moth has a musky odor which is confined to the male and is doubtless sexual. Some lizards have a musky odor which is heightened at the sexual season; crocodiles during the pairing season emit from their submaxillary glands a musky odor which pervades their haunts. In the same way elephants emit a musky odor from their facial glands during the rutting season. The odor of the musk-duck is chiefly confined to the breeding season.[61] The musky odor of the negress is said to be heightened during sexual excitement.
The predominance of musk as a sexual odor is associated with the fact that its actual nervous influence, apart from the presence of sexual association, is very considerable. Féré found it to be a powerful muscular stimulant. In former times musk enjoyed a high reputation as a cardiac stimulant; it fell into disuse, but in recent years its use in asthenic states has been revived, and excellent results, it has been claimed, have followed its administration in cases of collapse from Asiatic cholera. For sexual torpor in women it still has (like vanilla and sandal) a certain degree of reputation, though it is not often used, and some of the old Arabian physicians (especially Avicenna) recommended it, with castoreum and myrrh, for amenorrhoea. Its powerful action is indicated by the experience of Esquirol, who stated that he had seen cases in which sensory stimulation by musk in women during lactation had produced mania. It has always had the reputation, more especially in the Mohammedan East, of being a sexual stimulant to men; "the noblest of perfumes," it is called in _El Ktab_, "and that which most provokes to venery."
It is doubtless a fact significant of the special sexual effects of musk that, as Laycock remarked, in cases of special idiosyncrasy to odors, musk appears to be that odor which is most liked or disliked. Thus, the old English physician Whytt remarked that "several delicate women who could easily bear the stronger smell of tobacco have been thrown into fits by musk, ambergris, or a pale rose."[62] It may be remarked that in the _Perfumed Garden of Sheik Nefzaoui_ it is stated that it is by their sexual effects that perfumes tend to throw women into a kind of swoon, and Lucretius remarks that a woman who smells castoreum, another animal sexual perfume, at the time of her menstrual period may swoon.[63] Not only is musk the most cherished perfume of the Islamic world, and the special favorite of the Prophet himself, who greatly delighted in perfumes ("I love your world," he is reported to have said in old age, "for its women and its perfumes"),[64] it is the only perfume generally used by the women of a land in which the refinements of life have been carried so far as Japan, and they received it from the Chinese.[65] Moreover, musk is still the most popular of European perfumes. It is the perfumes containing musk, Piesse states in his well-known book on the _Art of Perfumery_, which sell best. It is certainly true that in its simple form the odor of musk is not nowadays highly considered in Europe. This fact is connected with the ever-growing refinement in accordance with which the specific odors of the sexual regions in human beings tend to lose their primitive attractiveness and bodily odors generally become mingled with artificial perfumes and so disguised. But, although musk in its simple form, and under its ancient name, has lost its hold in Europe, it is an interesting and significant fact that it is still the perfumes which contain musk that are the most widely popular.
Peau d'Espagne may be mentioned as a highly complex and luxurious perfume, often the favorite scent of sensuous persons, which really owes a large part of its potency to the presence of the crude animal sexual odors of musk and civet. It consists of wash-leather steeped in ottos of neroli, rose, santal, lavender, verbena, bergamot, cloves, and cinnamon, subsequently smeared with civet and musk. It is said by some, probably with a certain degree of truth, that Peau d'Espagne is of all perfumes that which most nearly approaches the odor of a woman's skin; whether it also suggests the odor of leather is not so clear.
There is, however, no doubt that the smell of leather has a curiously stimulating sexual influence on many men and women. It is an odor which seems to occupy an intermediate place between the natural body odors and the artificial perfumes for which it sometimes serves as a basis; possibly it is to this fact that its occasional sexual influence is owing, for, as we have already seen, there is a tendency for sexual allurement to attach to odors which are not the specific personal body odors but yet are related to them. Moll considers, no doubt rightly, that shoe fetichism, perhaps the most frequent of sexual fetichistic perversions, is greatly favored, if, indeed, it does not owe its origin to, the associated odor of the feet and of the shoes.[66] He narrates a case of shoe fetichism in a man in which the perversion began at the age of 6; when for the first time he wore new shoes, having previously used only the left-off shoes of his elder brother; he felt and smelt these new shoes with sensations of unmeasured pleasure; and a few years later began to use shoes as a method of masturbation.[67] Näcke has also recorded the case of a shoe fetichist who declared that the sexual attraction of shoes (usually his wife's) lay largely in the odor of the leather.[68] Krafft-Ebing, again, brings forward a case of shoe fetichism in which the significant fact is mentioned that the subject bought a pair of leather cuffs to smell while masturbating.[69] Restif de la Bretonne, who was somewhat of a shoe fetichist, appears to have enjoyed smelling shoes. It is not probable that the odor of leather explains the whole of shoe fetichism,--as we shall see when, in another "Study," this question comes before us--and in many cases it cannot be said to enter at all; it is, however, one of the factors. Such a conclusion is further supported by the fact that by many the odor of new shoes is sometimes desired as an adjuvant to coitus. It is in the experience of prostitutes that such a device is not infrequent. Näcke mentions that a colleague of his was informed by a prostitute that several of her clients desired the odor of new shoes in the room, and that she was accustomed to obtain the desired perfume by holding her shoes for a moment over the flame of a spirit lamp.
The direct sexual influence of the odor of leather is, however, more conclusively proved by those instances in which it exists apart from shoes or other objects having any connection with the human body. I have elsewhere in these "Studies"[71] recorded the case of a lady, entirely normal in sexual and other respects, who is conscious of a considerable degree of pleasurable sexual excitement in the presence of the smell of leather objects, more especially of leather-bound ledgers and in shops where leather objects are sold. She thinks this dates from the period when, as a child of 9, she was sometimes left alone for a time on a high stool in an office. A possible explanation in this case lies in the supposition that on one of these early occasions sexual excitement was young girls) and that the accidentally associated odor of leather permanently affected the nervous system, while the really significant contact left no permanent impression. Even on such a supposition it might, however, still be maintained that a real potency of the leather odor is illustrated by this case, and this is likewise suggested by the fact that the same subject is also sexually affected by various perfumes and odorous flowers not recalling leather.[70] It has been suggested to me by a lady that the odor of leather suggests that of the sexual organs. The same suggestion is made by Hagen,[72] and I find it stated by Gould and Pyle that menstruating girls sometimes smell of leather. The secret of its influence may thus be not altogether obscure; in the fact that leather is animal skin, and that it may thus vaguely stir the olfactory sensibilities which had been ancestrally affected by the sexual stimulus of the skin odor lies the probable foundation of the mystery.
In the absence of all suggestion of personal or animal odors, in its most exquisite forms in the fragrance of flowers, olfactory sensations are still very frequently of a voluptuous character. Mantegazza has remarked that it is a proof of the close connection between the sense of smell and the sexual organs that the expression of pleasure produced by olfaction resembles the expression of sexual pleasures.[73] Make the chastest woman smell the flowers she likes best, he remarks, and she will close her eyes, breathe deeply, and, if very sensitive, tremble all over, presenting an intimate picture which otherwise she never shows, except perhaps to her lover. He mentions a lady who said: "I sometimes feel such pleasure in smelling flowers that I seem to be committing a sin."[74] It is really the case that in many persons--usually, if not exclusively, women--the odor of flowers produces not only a highly pleasurable, but a distinctly and specifically sexual, effect. I have met with numerous cases in which this effect was well marked. It is usually white flowers with heavy, penetrating odors which exert this influence. Thus, one lady (who is similarly affected by various perfumes, forget-me-nots, ylang-ylang, etc.) finds that a number of flowers produce on her a definite sexual effect, with moistening of the pudenda. This effect is especially produced by white flowers like the gardenia, tuberose, etc. Another lady, who lives in India, has a similar experience with flowers. She writes: A scent to cause me sexual excitement must be somewhat heavy and _penetrating_. Nearly all white flowers so affect me and many Indian flowers with heavy, almost pungent scents. (All the flower scents are quite unconnected with me with any individual.) Tuberose, lilies of the valley, and frangipani flowers have an almost intoxicating effect on me. Violets, roses, mignonette, and many others, though very delicious, give me no sexual feeling at all. For this reason the line, 'The lilies and languors of virtue for the roses and raptures of vice' seems all wrong to me. The lily seems to me a very sensual flower, while the rose and its scent seem very good and countrified and virtuous. Shelley's description of the lily of the valley, 'whom youth makes so fair and _passion_ so pale,' falls in much more with my ideas. "I can quite understand," she adds, "that leather, especially of books, might have an exciting effect, as the smell has this _penetrating_ quality, but I do not think it produces any special feeling in me." This more sensuous character of white flowers is fairly obvious to many persons who do not experience from them any specifically sexual effects. To some people lilies have an odor which they describe as sexual, although these persons may be quite unaware that Hindu authors long since described the vulvar secretion of the _Padmini_, or perfect woman, during coitus, as "perfumed like the lily that has newly burst."[75] It is noteworthy that it was more especially the white flowers--lily, tuberose, etc.--which were long ago noted by Cloquet as liable to cause various unpleasant nervous effects, cardiac oppression and syncope.[76] When we are concerned with the fragrances of flowers it would seem that we are far removed from the human sexual field, and that their sexual effects are inexplicable. It is not so. The animal and vegetable odors, as, indeed, we have already seen, are very closely connected. The recorded cases are very numerous in which human persons have exhaled from their skins--sometimes in a very pronounced degree--the odors of plants and flowers, of violets, of roses, of pineapple, of vanilla. On the other hand, there are various plant odors which distinctly recall, not merely the general odor of the human body, but even the specifically sexual odors. A rare garden weed, the stinking goosefoot, _Chenopodium vulvaria_, it is well known, possesses a herring brine or putrid fish odor--due, it appears, to propylamin, which is also found in the flowers of the common white thorn or mayflower (_Cratægus oxyacantha_) and many others of the _Rosaceæ_--which recalls the odor of the animal and human sexual regions.[77] The reason is that both plant and animal odors belong chemically to the same group of capryl odors (Linnæus's _Odores hircini_), so called from the goat, the most important group of odors from the sexual point of view. Caproic and capryl acid are contained not only in the odor of the goat and in human sweat, and in animal products as many cheeses, but also in various plants, such as Herb Robert (_Geranium robertianum_), and the Stinking St. John's worts (_Hypericum hircinum_), as well as the _Chenopodium_. Zwaardemaker considers it probable that the odor of the vagina belongs to the same group, as well as the odor of semen (which Haller called _odor aphrodisiacus_), which last odor is also found, as Cloquet pointed out, in the flowers of the common berberry (_Berberis vulgaris_) and in the chestnut. A very remarkable and significant example of the same odor seems to occur in the case of the flowers of the henna plant, the white-flowered Lawsonia (_Lawsonia inermis_), so widely used in some Mohammedan lands for dyeing the nails and other parts of the body. "These flowers diffuse the sweetest odor," wrote Sonnini in Egypt a century ago; "the women delight to wear them, to adorn their houses with them, to carry them to the baths, to hold them in their hands, and to perfume their bosoms with them. They cannot patiently endure that Christian and Jewish women shall share the privilege with them. It is very remarkable that the perfume of the henna flowers, when closely inhaled, is almost entirely lost in a very decided spermatic odor. If the flowers are crushed between the fingers this odor prevails, and is, indeed, the only one perceptible. It is not surprising that so delicious a flower has furnished Oriental poetry with many charming traits and amorous similes." Such a simile Sonnini finds in the _Song of Songs_, i. 13-14.[78] The odor of semen has not been investigated, but, according to Zwaardemaker, artificially produced odors (like cadaverin) resemble it. The odor of the leguminous fenugreek, a botanical friend considers, closely approaches the odor given off in some cases by the armpit in women. It is noteworthy that fenugreek contains cumarine, which imparts its fragrance to new-mown hay and to various flowers of somewhat similar odor. On some persons these have a sexually exciting effect, and it is of considerable interest to observe that they recall to many the odor of semen. "It seems very natural," a lady writes, "that flowers, etc., should have an exciting effect, as the original and by far the pleasantest way of love-making was in the open among flowers and fields; but a more purely physical reason may, I think, be found in the exact resemblance between the scent of semen and that of the pollen of flowering grasses. The first time I became aware of this resemblance it came on me with a rush that here was the explanation of the very exciting effect of a field of flowering grasses and, perhaps through them, of the scents of other flowers. If I am right, I suppose flower scents should affect women more powerfully than men in a sexual way. I do not think anyone would be likely to notice the odor of semen in this connection unless they had been greatly struck by the exciting effects of the pollen of grasses. I had often noticed it and puzzled over it." As pollen is the male sexual element of flowers, its occasionally stimulating effect in this direction is perhaps but an accidental result of a unity running through the organic world, though it may be perhaps more simply explained as a special form of that nasal irritation which is felt by so many persons in a hay-field. Another correspondent, this time a man, tells me that he has noted the resemblance of the odor of semen to that of crushed grasses. A scientific friend who has done much work in the field of organic chemistry tells me he associates the odor of semen with that produced by diastasic action on mixing flour and water, which he regards as sexual in character. This again brings us to the starchy products of the leguminous plants. It is evident that, subtle and obscure as many questions in the physiology and psychology of olfaction still remain, we cannot easily escape from their sexual associations.
FOOTNOTES: [53] H. Beauregard, _Matière Médicale Zoölogique: Histoire des Drogues d'origine Animate_, 1901.
[54] Professor Plateau, of Ghent, has for many years carried on a series of experiments which would even tend to show that insects are scarcely attracted by the colors of flowers at all, but mainly influenced by a sense which would appear to be smell. His experiments have been recorded during recent years (from 1887) in the _Bulletins de l'Académie Royale de Belgique_, and have from time to time been summarized in _Nature_, e.g., February 5, 1903.
[55] David Sharp, _Cambridge Natural History: Insects_, Part II, p. 398.
[57] Mantegazza (_L'Amour dans l'Humanité_, p. 94) refers to various peoples who practice this last custom. Egypt was a great centre of the practice more than 3000 years ago.
[58] Hagen, _Sexuelle Osphrésiologie_, 1901, p. 226. It has been suggested to me by a medical correspondent that one of the primitive objects of the hair, alike on head, mons veneris, and axilla, was to collect sweat and heighten its odor to sexual ends.
[59] The names of all our chief perfumes are Arabic or Persian: civet, musk, ambergris, attar, camphor, etc.
[60] Cloquet (_Osphrésiologie_, pp. 73-76) has an interesting passage on the prevalence of the musk odor in animals, plants, and even mineral substances.
[61] Laycock brings together various instances of the sexual odors of animals, insisting on their musky character (_Nervous Diseases of Women_; section, "Odors"). See also a section in the _Descent of Man_ (Part II, Chapter XVIII), in which Darwin argues that "the most odoriferous males are the most successful in winning the females." Distant also has an interesting paper on this subject, "Biological Suggestions," _Zoölogist_, May, 1902; he points out the significant fact that musky odors are usually confined to the male, and argues that animal odors generally are more often attractive than protective.
[63] Lucretius, VI, 790-5.
[64] Mohammed, said Ayesha, was very fond of perfumes, especially "men's scents," musk and ambergris. He used also to burn camphor on odoriferous wood and enjoy the fragrant smell, while he never refused perfumes when offered them as a present. The things he cared for most, said Ayesha, were women, scents, and foods. Muir, _Life of Mahomet_, vol. iii, p. 297.
[65] H. ten Kate, _International Centralblatt für Anthropologie_, Ht. 6, 1902. This author, who made observations on Japanese with Zwaardemaker's olfactometer, found that, contrary to an opinion sometimes stated, they have a somewhat defective sense of smell. He remarks that there are no really native Japanese perfumes.
[68] P. Näcke, "Un Cas de Fetichisme de Souliers," _Bulletin de la Société de Médecine Mentale de Belgique_, 1894.
[70] Philip Salmuth (_Observationes Medicæ_, Centuria II, no. 63) in the seventeenth century recorded a case in which a young girl of noble birth (whose sister was fond of eating chalk, cinnamon, and cloves) experienced extreme pleasure in smelling old books. It would appear, however, that in this case the fascination lay not so much in the odor of the leather as in the mouldy odor of worm-eaten books; "_fætore veterum liborum, a blattis et tineis exesorum, situque prorsus corruptorum_" are Salmuth's words.
[71] _Studies in the Psychology of Sex_, vol. iii, "Appendix B, History VIII."
[74] In this connection I may quote the remark of the writer of a thoughtful article in the _Journal of Psychological Medicine_, 1851: "The use of scents, especially those allied to the musky, is one of the luxuries of women, and in some constitutions cannot be indulged without some danger to the morals, by the excitement to the ovaria which results. And although less potent as aphrodisiacs in their action on the sexual system of women than of men, we have reason to think that they cannot be used to excess with impunity by most."
[77] In Normandy the _Chenopodium_, it is said, is called "conio," and in Italy erba connina (con, cunnus), on account of its vulvar odor. The attraction of dogs to this plant has been noted. In the same way cats are irresistibly attracted to preparations of valerian because their own urine contains valerianic acid.
[78] Sonnini, _Voyage dans la Haute et Basse Egypte_, 1799, vol. i. p. 298.
V.
The Evil Effects of Excessive Olfactory Stimulation--The Symptoms of Vanillism--The Occasional Dangerous Results of the Odors of Flowers--Effects of Flowers on the Voice.
The reality of the olfactory influences with which we have been concerned, however slight they may sometimes appear, is shown by the fact that odors, both agreeable and disagreeable, are stimulants, obeying the laws which hold good for stimulants generally. They whip up the nervous energies momentarily, but in the end, if the excitation is excessive and prolonged, they produce fatigue and exhaustion. This is clearly shown by Féré's elaborate experiments on the influences of odors, as compared with other sensory stimulants, on the amount of muscular work performed with the ergograph.[79] Commenting on the remark of Bernardin de Saint-Pierre, that "man uses perfumes to impart energy to his passion," Féré remarks: "But perfumes cannot keep up the fires which they light." Their prolonged use involves fatigue, which is not different from that produced by excessive work, and reproduces all the bodily and psychic accompaniments of excessive work.[80] It is well known that workers in perfumes are apt to suffer from the inhalation of the odors amid which they live. Dealers in musk are said to be specially liable to precocious dementia. The symptoms generally experienced by the men and women who work in vanilla factories where the crude fruit is prepared for commerce have often been studied and are well known. They are due to the inhalation of the scent, which has all the properties of the aromatic aldehydes, and include skin eruptions,[81] general excitement, sleeplessness, headache, excessive menstruation, and irritable bladder. There is nearly always sexual excitement, which may be very pronounced.[82] We are here in the presence, it may be insisted, not of a nervous influence only, but of a direct effect of odor on the vital processes. The experiments of Tardif on the influence of perfumes on frogs and rabbits showed that a poisonous effect was exerted;[83] while Féré, by incubating fowls' eggs in the presence of musk, found repeatedly that many abnormalities occurred, and that development was retarded even in the embryos that remained normal; while he obtained somewhat similar results by using essences of lavender, cloves, etc.[84] The influence of odors is thus deeper than is indicated by their nervous effects; they act directly on nutrition. We are led, as Passy remarks, to regard odors as very intimately related to the physiological properties of organic substances, and the sense of smell as a detached fragment of generally sensibility, reacting to the same stimuli as general sensibility, but highly specialized in view of its protective function.
The reality and subtlety of the influence of odors is further shown, by the cases in which very intense effects are produced even by the temporary inhalation of flowers or perfumes or other odors. Such cases of idiosyncrasy in which a person--frequently of somewhat neurotic temperament--becomes acutely sensitive to some odor or odors have been recorded in medical literature for many centuries. In these cases the obnoxious odor produces congestion of the respiratory passages, sneezing, headache, fainting, etc., but occasionally, it has been recorded, even death. (Dr. J.N. Mackenzie, in his interesting and learned paper on "The Production of the so-called 'Rose Cold,' etc.," _American Journal of Medical Sciences_, January, 1886, quotes many cases, and gives a number of references to ancient medical authors; see also Layet, art. "Odeur," _Dictionnaire Encyclopédique des Sciences Médicales_.)
An interesting phenomenon of the group--though it is almost too common to be described as an idiosyncrasy--is the tendency of the odor of certain flowers to affect the voice and sometimes even to produce complete loss of voice. The mechanism of the process is not fully understood, but it would appear that congestion and paresis of the larynx is produced and spasm of the bronchial tube. Botallus in 1565 recorded cases in which the scent of flowers brought on difficulty of breathing, and the danger of flowers from this point of view is well recognized by professional singers. Joal has studied this question in an elaborate paper (summarized in the _British Medical Journal_, March 3, 1895), and Dr. Cabanès has brought together (_Figaro_, January 20, 1894) the experiences of a number of well-known singers, teachers of singing, and laryngologists. Thus, Madame Renée Richard, of the Paris Opera, has frequently found that when her pupils have arrived with a bunch of violets fastened to the bodice or even with a violet and iris sachet beneath the corset, the voice has been marked by weakness and, on using the laryngoscope, she has found the vocal cords congested. Madame Calvé confirmed this opinion, and stated that she was specially sensitive to tuberose and mimosa, and that on one occasion a bouquet of white lilac has caused her, for a time, complete loss of voice. The flowers mentioned are equally dangerous to a number of other singers; the most injurious flower of all is found to be the violet. The rose is seldom mentioned, and artificial perfumes are comparatively harmless, though some singers consider it desirable to be cautious in using them.