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. FOOTNOTES: [79] Féré, _Travail et Plaisir_, Chapter XIII.