iv THE SENSE OF SMELL 177 



movements; the latter o\\v ilieir 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 Froblich 

 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.). 



(6) 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, chamomile). 

 (<1) Odours of lemon and of rose (palisander, sandal-wood, cedar- 



wood, etc.). 

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



aldehyde, nitre-benzol). 



III. Class : Odori balsamici (Linnaeus) 



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



blossom, acacia, etc.). 



(6) Liliaceous odours (iris, nan-issus, hyacinth, violet, mignonette). 

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



cumarine, heliotrope). 

 I V. Class : Odori aiidmxtnci (Linnaeus) 

 (a) Odours of amber. 

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



some fungi). 

 \ . ( 'lass : Oi.h> r I agliacei (Linuaeu>) 



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



asafoetida, gum ammonicum, ichthyol. 



(6) Arsenuretted hydrogen, phosphoretted hydrogen, trimethylamine. 

 (c) Chlorine, bromine, iodine, quinine. 



VI. Class : Odori e/n/i/r> u maiici (Hallen 



(") Odour of roast co flee, toasted bread, tobacco smoke, pyrocatech in, 



guiacol, creosol, acrolein, pindiue. 

 (1>) Odour of ainylic alcohol and homologues, benzol, toluol, xylol, 



phenol, creolin, iiaphthalin, naphlhol. 



VII. Class : Odori caprilici (Linn n 



(a) Caproic acid and homologues, cheese, sweat, putrefying bone.-, 

 ' 



(6) Cat's urine, vaginal secretion, spermatic fluid, chr-i nut (lour. 

 VOL. IV N 



