304 
Mr. Bell on the 
This notion of a fluid moving backwards and forwards in 
the tubes of the nerves, equally adapted to produce motion 
and sensation, has perpetuated the error, that the different 
nerves of sensation are appropriated to their offices by the 
texture of their extremities, “ that there exists a certain re- 
lation between the softness of the nervous extremities, and 
the nature of the bodies which produce an impression on 
them.” On the contrary, every nerve of sense is limited in 
its exercise, and can minister to certain perceptions only. 
Whatever may be the nature of the impulse communicated 
to a nerve, pressure, vibration, heat, electricity, the percep- 
tion excited in the mind will have reference to the organ 
exercised, not to the impression made upon it. Fire will not 
give the sensation of heat to any nerve but that appropriated 
to the surface. However delicate the retina be, it does not 
feel like the skin. The point which pricks the skin being 
thrust against the retina, will cause a spark of fire or a flash 
of light. The tongue enjoys two senses, touch and taste ; 
but by selecting the extremity of a particular nerve, or what 
is the same thing, a particular papilla, we can exercise either 
the one or the other sense separately. If we press a needle 
against a nerve of touch, we shall feel the sharpness, and 
know the part of the tongue in contact with the point ; but 
if we touch a nerve of taste, we shall have no perception of 
form or of place, we shall experience a metallic taste. 
The innovations of the celebrated continental authority 
Bichat, did not bring us a step nearer the truth. When he 
at once threw off respect for his contemporaries, and for the 
authority of those who had preceded him, he equally disre- 
garded the facts of anatomy. There may be merit in taking 
