280 ox THE SENSES. 



observations on sick persons, that all the presumed acute burning, itcliing, or 

 ]iungent sensations of smell are brought about, not by an excitement of the real 

 and exclusive nerve of smell, but of the same nerves which, when gently touched, 

 ]-roduce a ticklish feeling. There are individuals who do not feel the scent of 

 either roses or violets, because their nerve of smell has been deprived by sick- 

 ness of its active faculty, but who, nevertheless, are very well accessible to the 

 pungent sensation caused by the vapor of sal ammoniac rising into the nostril. 

 Everybody knows, from personal experience, that when deprived of all smell 

 by a severe cold — that is, when, in consequence of an inflammation of the cuticle 

 of the nose, smelling substances have ceased to act upon the extremities of the 

 nerve of smell, he is still accessible to the acute sensation caused by spirits of 

 sal ammoniac or mustard, just because this sensation is produced by the vapors 

 of these substances penetrating the nerves of touch. On the other hand, it also 

 frequently happens that we mistake a sensation of smell for one of taste, be- 

 cause the two happen to coincide. Thus we speak of the aromatic taste of a 

 substance which has an aromatic scent ; while we have that substance on our 

 tungae, deriving from it a real (bitter or sweet, &c^ sensation of taste, vapors 

 from it also enter our nasal cavity, which by the throat is connected with the 

 mouth, and there produce the aromatic sensation of smell. As this latter 

 coincides with a real sensation of taste, as well as with a sensation of touch on 

 the tongue, which makes us believe the cause of the sensation to be within our 

 mouth, while there is no distinct indication of the nasal seat of the sensation of 

 smell, we place this too in the oral cavity, mistaking it for a sensation of taste. 

 Many a connoisseur of wine may, indeed, be surprised to hear that while tasting 

 that liquor his nose is as actively engaged as his tongue ; that his praise or 

 blame is being determined by smell no less than taste all the time he, Avith 

 closed eyes and all kinds of grimaces, moves the noble juice of the vine to and 

 lio on his tongue. 



In spite of much earnest research, we know very little of the organs of smell, 

 and that little cannot easily be made clear tcf the non-scientific inquirer. Before 

 all, we must refer to the explanations which we have given in our introduction 

 on the services of nerves of sense in general, and the means which enable them 

 to perform such services. A sensation of smell takes place when a certain 

 nerve, called the nerve of smell, which rises in the brain and spreads its extremi- 

 tiQs through the nose, becomes affected by a gaseous smelling substance ; that is 

 to say, when the prScess which we above designated as the " nervous current" 

 is produced in that nerve, rapidly extending from the seat of affection, the cuticle 

 of the nose, along the fibres of the nerve, to the brain, Avhere, by means of a 

 peculiar apparatus, it acts upon the mind. In itself, the nerve of smell is a 

 nerve like all others ; its fibres have the same appearance, the Same qualities as 

 the nerves of touch or sight, or even as a miiscle nerve, the current of which in 

 the muscle produces contraction, and, through it, motion of the limbs. Even 

 the current which in the nerve of smell rushes to the brain, while conveying a 

 sensation of smell, is, as we have seen, very probably, essentially like the 

 current in the fibre of the nerve of sight, by which this produces a sensatiofi 

 of sight; or like the current in the fibre of the motive nerve, which, spi'eading 

 from the brain to the extremity of the fibre, acts upon the muscle and causes a 

 compulsory contraction. What, then, constitutes this nerve, essentially the 

 i^ame with all others, a nerve of smell ? What explains, notwithstanding this 

 identity with other nerves, the specific kind, incomparable with others, of its 

 faculties % Similar reasons to those which explain Avhy the same copper wire, 

 with the same electric current, now moves the hand of a clock and now ignites 

 powder; that is, the nature of the apparatus at the extremities of the nerve of 

 smell in the cuticle of the nose and in the brain. In the cuticle of the nose 

 we must suppose some specific apparatus arranged at the extremities of the 

 nerve fibres, which effect that a current is produced in the fibres by a smelling 



