286 ON THE SENSES. 



odorous substance and the nerve of Bmell, are exceedingly tender and fmgile, 

 being easily burst by water which soaks into them. If those cellules be 

 really the. end apparatus of the nerves of smell in which a nervous affection 

 is first produ-ed by the odorous substance, we cannot be surprised to fiud that 

 after their destruction by water odorous substances are unable to excite the nerve 

 of smell. It has been proved, indeed, by direct experiments, that pui;e water 

 poured into the nasal cavity in the above-mentioned way for some time suspends 

 the faculty of smell, so that after its removal from the nose even strong-scented 

 gases are not smellable when inhaled ; and so it is more than probable that this 

 destructive influence of the water causes the negative result of the experiments 

 made with liquid solutions of odorous substances. 



It would be very desirable to find a liquid which would not affect the 

 cellules of the cuticle of the nose, and to repeat with it the same experiments. 

 Moderately thiimed sugar, or albumen solutions, or liquefied blood containing 

 its red globules, would probably be found available in this respect. To my 

 knowledge, however, no such experiments have been made. But should even 

 these produce the same negative result — should, for instance, can de Cologne, 

 dissolved in water and poured into the nasal cavity, cause no sensation of smell, 

 there would still remain one last possible objection to the validity of the con- 

 clusion that odorous substances are powerless in a state of solution, and that 

 the gaseous form is the only condition of their smellability. For v/ith the simple 

 filling of the nasal cavity with a solution of an odorous substance there is still 

 wanting another condition of the rise of a sensation of smell, to wit, the motion 

 on the cuticle of the medium saturated with the odorous substance. We have 

 already alluded to the daily experience which indubitably proves the ineffective- 

 ness in the nasal cavity of odorous air in a state of rest. If we enter an ill- 

 smelling atmosphere we best defend ourselves by closing the nose ; but we 

 avoid the sensation of smell also by breathing through the mouth alone. There 

 can be no doubt that when the nosti'ils are open the external air which is satu- 

 rated with odorous substance mingles with the air in the nasal cavity, and that 

 the odorous substance is thus brought in contact with the cuticle. The absence 

 of a sensation of smell can, therefoi-e, have no other cause but the immobility of 

 the air. As soon as we cause the lightest draught by opening the nasal channel, 

 sensation immediately arises. Every smoker can convince himself in an 

 agreeable way, and without exposing himself to a bad atmosphere, of the cor- 

 rectness of this statement. When holding the smoking cigar as closely near 

 his nostrils as possible, without burning himself, ho will feel warmth and a 

 certain tickling in the nasal cavity from the entering smoke, but no trace of a 

 real smell as long as he entirely avoids breathing through the nose ; but at the 

 lightest draught caused by nasal inhalations a more intense sensation of smell 

 will immediately take place. Ladies can use, instead ^f the smoking cigar, a 

 little fiask of perfume with the same satisfactory result. The question hero 

 arises : In what way does the motion of the scented air cause the rise of a sen- 

 sation x)f smell 1 This question, too, we must unfortunately leave without a 

 precise answer. The nearest we find is not sufficient. The facalty of receiving 

 impressions of smell by no means extends all over the wall of the double nasal 

 cavity, being limited to the upper sections, to the middle and upper nasal shells, 

 and the upper part of the partition. Through the cuticle of these parts only 

 the nerve of smell spreads its fibres. The cuticle of the lower nasal shell, of 

 the bottom of the nasal cavity, and of the lower part of the partition, is sup- 

 plied with fibres by another nerve, which has been proved to be a nerve of 

 toiich, and serves as a medium for the sensation of smell of the nasal cavity. 

 It is the excitement of this other nerve, by a light touch, that causes the 

 tickling afiection which produces sneezing, and the afl'ection of which by sharp 

 steam, for instance, from burning sulphur or spirit of sal ammoniac, produces those 

 acute burning or itching sensations of touch which, by the common peoole, are 



