iv THE SENSE OF SMELL 



movements ; the latter owe their origin not merely to stimu- 

 lation of the olfactory nerve but also to that of the nasal 

 branches of the trigeminal, as by chlorine, iodine, bromine, 

 nitric acid, ammonia, oil of mustard, rape, etc., which always 

 produce reflex movements. But if the fact is more closely 

 investigated, it is seen that very few odorous substances excite 

 pure olfactory sensations. Nearly all, when they act with a 

 certain intensity, affect not only the olfactory sensibility but also 

 the general sensibility of the nasal mucous membrane. Thus, oil 

 of juniper and of bergamot and even camphor, which Frohlich 

 considered to be purely olfactory substances, irritate not only the 

 nasal mucosa but the conjunctiva of the eye as well. 



In order to give some notion of the innumerable qualitative 

 varieties of odours the classification of (purely olfactory) odorous 

 substances into nine groups proposed by Zwaardemaker may be 

 reproduced : 



I. Class : Odori eterei (Lorry) 



(a) Essences of fruits used in perfumery (apple, pine-apple, pear, etc.). 



(b) Beeswax. 



(c) Ethers, aldehydes, ketones. 



II. Class : Odori aromatici (Linnaeus) 



(a) Camphoric odours (camphor, borneol, patchouli, rosemary, 

 eucalyptus, turpentine). 



(6) Odours of drugs (clove, ginger, pepper). 



(c) Odours of anise and lavender (menthol, oil of fennel, arnica, 

 thymol, cliamomile). 



(d} Odours of lemon and of rose (palisander, sandal-wood, cedar- 

 wood, etc.). 



(e) Odour of bitter almond (hydrocyanic acid, benzoic and salicylic 

 aldehyde, nitro-benzol). 



III. Class : Odori balsamici (Linnaeus) 



(a) Odours of flowers (jessamine, syringa, lilies of the valley, orange- 



blossom, acacia, etc.). 



(b) Liliaceous odours (iris, narcissus, hyacinth, violet, mignonette). 



(c) Vanilla odours (benzoin, balsam of Peru and Tolu storax, 



cumarine, heliotrope). 



IV. Class : Odori ambrosiaci (Linnaeus) 

 (a) Odours of amber. 



(6) Odours of musk (nitro butyltoluol, ox -bile, many animals, 

 some fungi). 



V. Class : Odori agliacei (Linnaeus) 



(a) Sulphuretted hydrogen, hydrogen carbide, vulcanised rubber, 



asafoetida, gum ammonicum, ichthy.ol. 



(b) Arsenuretted hydrogen, phosphoretted hydrogen, trimethylamine. 



(c) Chlorine, bromine, iodine, quinine. 



VI. Class : Odori empireumatici (Haller) 



I (a) Odour of roast coffee, toasted bread, tobacco smoke, pyrocatechin, 



guiacol, creosol, acrolein, piridine. 

 (b) Odour of amylic alcohol and homologues, benzol, toluol, xylol, 

 phenol, creolin, naphthalin, naphthol. 

 VII. Class : Odori caprilici (Linnaeus) 

 (a) Caproic acid and homologues, cheese, sweat, putrefying bones, 

 rancid fat. 

 (b) Cat's urine, vaginal secretion, spermatic fluid, chestnut flour. 

 VOL. IV N 



