Insects. 1583 



body a most important part, being the sole communicating medium 

 between the various organs and the directing mind and instincts, con- 

 veying to the latter the indications of external bodies and forces, and 

 from it the commands by which every muscle acts in harmony for the 

 production of the different organic functions and voluntary movements. 

 I am here compelled to express my opinion, that in supposing neurine 

 and sensation to be absolutely inseparable, Mr. Wollaston has fallen 

 into a most unaccountable mistake. I would beg to refer him to the 

 works of the celebrated Sir Chas. Bell, whose discoveries, together 

 with those of Dr. Marshall Hall, on the reflex function, rank as the 

 most important in that very obscure branch of physiology. Sir C. Bell 

 discovered that no one simple nerve possesses more than one of the 

 many functions which neurine is capable of exercising; that even a 

 nerve which conveys both power and sensation arises by a double 

 root, and therefore consists of two nerves rather than of one ; more- 

 over, that one of these roots springs from a distinct tract of neurine 

 extended all down the spinal cord ; and that, by dividing one or other 

 of these roots, he could deprive that portion of the body to which the 

 nerve is distributed, either of motion or sensation ; also, that in some 

 parts, as in the face for example, the nerve which communicates 

 sensation has its origin far removed from that which gives the power 

 of motion to the same part of the body. This I think all must 

 acknowledge is a satisfactory proof that neurine and sensation are by 

 no means necessarily connected ; indeed, although the latter pre-sup- 

 poses the existence of the former, the converse can no longer be main- 

 tained. Let us now consider more particularly what is implied by the 

 word sensation or bodily feeling: it appears to me that under this 

 term have been confounded a multitude of varied perceptions which 

 the animal body has of things eternal to it ; — the delicate sensation 

 in the skin, by which we recognise the presence and characters of an 

 object with which it is in contact ; the sensation of resistance felt when 

 a limb is moved through a dense medium, or pushed against a solid 

 which yields not to its action ; the pricking pain (existing only in the 

 skin), which is Nature's kind warning, lest the intrusion of a pointed 

 body should harm the organisms beneath; a blow which, though 

 scarcely felt on the softer flesh, when received on a projecting bone 

 thrills through it with agonizing pain ; the sensation of heat or cold, 

 alike perceived when the body causing it is applied to the outer skin, 

 or swallowed into the stomach; — all these perceptions, the different 

 warnings against varied dangers, have been grouped together under 

 the one comprehensive name of feeling. They are but few of the dif- 



