FUNCTIONS OF MOTOR AND SENSORY NERVES 103 



the difficulty of accounting for this muscular element in the dis- 

 tribution of the nerve. He now says (p. 164) that . 



"for a time I believed that the fifth nerve, which is the sensitive 

 nerve of the head and face, did not terminate in the muscles, but 

 only passed through them to the skin." 



But he implies that he now admits that it does terminate, as 

 he first thought, in the muscles. And since now it is certainly 

 sensory, its ramifications in the muscle must be the sensory 

 nerves of muscles. 



The principal object of this paper of 1826 is therefore 



"to demonstrate that where nerves of different functions take their 

 origin apart and run a different course, two nerves must unite in the 

 muscles, in order to perfect the relations betwixt the brain and these 

 muscles " (p. 164). 



He opens his " demonstration " or argument by saying that 



" it may be within the recollection of the Society that my first 

 paper [of 1821] showed the difference of the nerves of the face ; 

 by dividing one nerve sensation was destroyed, whilst motion 

 remained ; and by dividing the other motion was stopped, 

 whilst sensibility remained entire." 



(This is in fact an appropriation to himself of the lion's share 

 of a discovery in which he no doubt participated but to which 

 the principal contributors were Magendie and Mayo.) 



He then proceeds to argue that " the profuse supply to 

 muscles of nerves whose office it is to convey sensation, in 

 addition to motor nerves through which motion is excited," 

 signifies that "there must be a sense of the condition of the 

 muscle communicated to the brain as well as energy proceed- 

 ing^*^ the brain tozvards the muscles;" and on p. 170 as the 

 conclusion of his "demonstration" states that 



" between the brain and the muscles there is a circle of nerves; one 

 nerve conveys the influence from the brain to the muscle, another 

 gives the sense of the condition of the muscle to the brain." 



This conclusion of Bell's demonstration is the conclusion of 

 an argument in which the essential data were supplied by the 

 definite experiments of Magendie and of Mayo and of which 

 the general idea had been most clearly outlined by Walker in 



