0? NATURAL HISTORY. 169 



fedtly fimilar in every part of the body, fhould, when dlftrU 

 buted over the eye, the ear, the tongue, the nofe, convey to 

 the mind feelings fo different, is the moft myfterious part of 

 this fubje(St. When M. de Bonnet tells us, that every organ 

 of fenfe probably confifis of fibres fpecifically different 5 and 

 that thefe fibres are particular fenfes endowed with a peculiar 

 manner of a£ling, correfponding to the perceptions they ex-j 

 cite in the mind ; he means to reafon ; but he does no 

 more than give a circumlocution for the h€t 



OF SMELLING. 



IN man, and many other animals, the organ by which the 

 fenfe of fmelling is conveyed to the mind, has received the 

 general appellation of mfe, or noflrils. The more immediate 

 inftrument of this fenfation is a foft, vafcular, porous mem- 

 brane, covered with numerous papillae, and is known by the 

 name of membrana pituitariay or membrana Schnmderiana. This 

 membrane is totally covered with infinite ramifications and 

 convolutions of the olfactory nerves. Thefe nerves are air 

 moft naked, and expofed to the action of the air which paf- 

 fes through the nofe in performing the fun<rtion of refpira- 

 tion. But Nature, ever attentive to the eafe and conveni- 

 ence of her creatures, has furnilhed the noflrils with a num° 

 ber of glands, or fmall arteries, which fecrete a thick infipid 

 mucus. By this mucus, the olfactory nerves are defended 

 from the a61-ion of the air, and from the painful ftimuli of 

 acrid odours. 



The odours perceived by finelling are extremely various. 

 Some of them convey to us the moft delightful and refrefli- 

 ing fenfations, and others are painful, noxious, and difguft- 

 ing. All bodies in Nature, whether folid or fluid, whether 

 animated or inanimated, continually fend forth to the air 

 certain efiluvia or emanations from their refpedlive fubftan- 

 ces. Thefe efiluvia float in the atmofphere, and a6i: upo» 



