SEffSE OF SMELL IN FISHfeS. 351 



scrtsation of tastes? These questions I shall proceed to 

 examine. 



Tastes and smells are nearly of the same nature: both Tastes and 

 sensations are produced by the physical and chemical quali-^'^^^^^ analo- 

 ties of bodies. We know, in fact, that very minute par- . 

 tides arc continually separating from certain substances, 

 which, without being decomposed, come to act immediately 

 upon animals at that point of their surface alone, where 

 they can manifest their presence. This phenomenon is 

 effected by the intervention of a fluid medium, and a sort 

 of contact*. 



All the conditions necessary for the impression or sensa- The organs ia 

 tlon of taste are united therefore in the organ under exa- fectl^"^ia^^ ted 

 mination, and the nature of the substances that may pro- to the sense of 

 duce it. First, the organ is placed secure in a cavity: ft^^^^^* 

 opens and shuts at the will of the animal, it admits or re. 

 jects emanations at pleasure. Secondly, the sentient sur- 

 face receives numerous and bulky nerves from the fifth pair; 

 it is soft, moist, atid mucous ; and it presents a great sur- ^ 

 face in a large space. Thirdly, it appears in a certain de^ 

 gree to supply the place of the organ of taste, which 

 cannot exist in the mouth of fishes from the very mechanism 

 of their respiration. 



It seems to follow then from all these circumstances, that General con-r 

 the organ of taste in fishes does not reside in the mouth : ^ "^^°^^^" 

 that the sensation of taste is probably imparted to them by ' 

 the apparatus, which has hitherto been considered, as 

 adapted to perceive the emanations of odorate bodies: and 

 Lastly, that no real smell can be. perceived in water. 



* I have already had occasion to enlarge on these general ideas 

 in a paper on the organ of smell in insects, ^'i)ich I published ten 

 years ago, and which may be found in tJie second volume of the 

 Magazin Encyclop^dique, p. 435, 



VII. On 



