164 Mr. Bell on the nervous circle which connects 



show that every muscle has two nerves, of different proper- 

 ties, supplied to it. This I could not have ascertained by 

 examination of the spinal nerves alone, because of the inti- 

 mate union of all their fibres ; I had recourse therefore to 

 the nerves of the head. By prosecuting those enquiries, 

 which led to the distinction of the different classes of nerves, 

 I hope now 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. 



It may be in the recollection of the Society, that my first 

 Paper 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. 



Other parts of the nervous system since that time have 

 engaged my attention ; and it is only now that I am able to 

 make full use of the facts announced in my first Paper, which 

 were indeed expected to lead to further improvement of our 

 knowledge of the animal oeconomy . When I distinguished the 

 two classes of nerves going to the muscles of the face, and 

 divided the motor nerve, and when the muscles were de- 

 prived of motion by this experiment, the natural question 

 suggested itself — of what use are the nerves that remain 

 entire ? 



For a time I believed that the fifth nerve, which is the 

 sensitive nerve of the head and face, did not terminate in the 

 substance of the muscles, but only passed through them to 

 the .skin; and I was the more inclined to this befief on ob- 

 serving, that the muscular parts when exposed in surgical 



