44-8 Analyses of a Series of Papers, by Mr. C. Bell, 



the purpose of governing the muscles, nor of conveying sen- 

 sation. With all this apparent simplicity of doctrine, there 

 never has been presented such a crude heap of errors, in the 

 history of any department of science. 



" These notions were obviously founded on the mistake, that 

 the same nerve served different purposes, and that a fluid 

 moved in the same tube outwards to stimulate the muscles, 

 and inwards to convey sensation of external impressions. So 

 inconsistent are those opinions with the structure of the frame, 

 that the simplest dissection proves them false. 



" So far is it from being true that ganglia cut off sensation, 

 that I have ascertained, and proved by experiment, that all 

 die nerves, without a single exception, which bestow sensibility 

 from the top of the head to the toe, have ganglia on their 

 roots ; and those which have no ganglia are not nerves of sen- 

 sation, but are for the purpose of ordering the muscular frame. 

 " The hypothesis, that the nervous fluid streams out from the 

 great ofticina along the nerves, has had an unfortunate in- 

 fluence in directing the labours of the experimentalists. During 

 the last age it kept the pupils of Haller engaged in inquiries 

 regarding the influence of the nerves: de nutritione imprimis 

 nervosa : and de nervorum in arterias wiper io ■, and the interest 

 of this question has not subsided, but, on the contrary, has in- 

 creased among us. 



" 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 tex- 

 ture of their extremities, " that there exists a certain relation 

 between the softness of the nervous extremities, and the na- 

 ture 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, pres- 

 sure, vibration, heat, electricity, the perception 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. Hew- 

 ever delicate die retina be, It does not feel like the skin. 

 The point which pricks the skin being thrust against the re- 

 tina, will cause a spark of fire or a flash of light. The tongue 

 enjoys two senses, touch and taste ; but by selecting the ex- 

 tremity 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 



