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 
substanee of the muscles, but only passed through them to 
the skin ; and I was the more inclined to this belief on ob- 
serving, that the muscular parts when exposed in surgical 
