110 SENSATION AND ITS OBJECTS. 



are applied to the olfactory nerves, through th< 

 medium of the scneiderian membrane: odor iu 

 general, is the genus, the quality of those odors 

 the species, whether aromatic or fetid. In the 

 organs of taste, the sensation of flavor is excited 

 by the different substances more especially re- 

 ceived for food, and which are applied to the 

 nerves of the tongue ; while flavor in general, 

 constitutes the genus, the variety of sensations 

 which different kinds of food produce, consti- 

 tutes the species. In the organ of vision, the 

 rays of color impressed on the retina of the eye, 

 excite the sensation of illumination in general, 

 (and like different articles of food which excite 

 different flavors,) different bodies conveyed to 

 the eye, produce different colors. Every sub- 

 stance, therefore, in nature, which exists, of 

 which the eye has any cognisance whatever, 

 whether it is black or white, brown or yellow ; 

 or, in short, whatever color it may assume, so 

 long as it exists, the sensation of ill animation 

 piust be considered to be colored. 



Had physiologists and chemists been proper- 

 ly informed of the distinction which exists be- 

 tween impression and sensation between the 

 thing received and the receiver between the 

 substance without and the sensitive principle 

 within we should have been spared the pain 

 of hearing opinions promulgated and taught by 

 those few, very few individuals, who lay down 

 law, and who have been deluding the world 



