PROPERTIES AND FUNCTIONS 



eyes, ears, tongue, lips, nose, and ends of the fingers are 

 more abundantly supplied with nerves than any other, part 

 of the body. The immediate instruments of sensation are 

 small nervous papilla;, which are soft pulpy terminations of 

 the nerves. These papillae cover the whole surface of the 

 skin, but they may be seen more distinctly, for they are 

 more fully developed on the tongue and ends of the fingers 

 than any other organs which we can without difficulty ex- 

 amine with the naked eye. ' When examining or enjoying 

 an object,' says Smellie, ' it is natural to inquire what are 

 the changes produced in the nervous papillae or organs 

 of sensation. If an object possessed of agreeable feel- 

 ings is perceived, the nervous papillae instantly extend 

 themselves, and from a state of flaccidity become com- 

 paratively rigid. This extension of the papillae is not 

 conjectural, but it is founded on anatomical examination, 

 and may be felt by persons of acute aad discerning sensa- 

 tion. When a man in the dark inclines to examine any 

 substance in order to discover its figure or other qualities, 

 he perceives a kind of rigidity at the tips of his fingers. 

 If they are kept long in this state, the tension of the 

 nervous papillae will produce a kind of pain or anxiety 

 which it is impossible to describe. If a small insect 

 crawls on a man's hand when the papillae are flaccid, its 

 movements are not perceived ; but if he sees the animal 

 he immediately extends his papilla), and feels all its mo- 

 tions. If a body be present, which in the common state 

 of the nerves has scarcely any sensible odor, by ex- 

 tending the papilla} of the nostrils an agreeable, disa- 

 greeable or indifferent smell will be perceived. When 

 two persons are whispering, and we wish to know what 

 is said, we stretch the papillae of the ear, and an impres- 

 sion is made on them. If the sound is too low to make 

 an impression on the papillae in their natural flaccid 

 state, we are apt to overstretch them, and this produces 

 a painful or disagreeable feeling. When we examine a 

 minute object with the naked eye, a pain is propagated 

 over every part of that organ. Several causes may con- 

 cur in producing this pain, such as the dilating of the 

 pupil or the adjusting of the crystalline lens ; but the 

 chief cause must be ascribed to the preternatural exten-- 



