2 92 
Mr. Bell on the 
of the surfaces of the eye, as well as of the skin around the 
eye. 
By experiment it can farther be made evident, that the 
sensibility of the eye enjoyed through the ophthalmic nerve, 
does not bestow on the organ directly, the power of com- 
bining the muscles, either for the defence of the eye, or for 
any other purpose. The impression must be referred back 
to the brain, and the muscles excited by their proper nerves. 
I have not been able to excite the motion of the eye by irri- 
tating the ophthalmic division of the fifth after the division of 
its root,* and in the instance just given, the eyelids did not 
move when the surface of the eye was irritated, because no 
sensation was conveyed inward to the sensorium, and conse- 
quently no mandate transmitted from it. The young lady 
could see, and could move the eye and eyelids ; the eye itself 
was irritated by touch, as appeared from the rising inflam- 
mation ; but by the insensibility of the ophthalmic nerve, a 
link was lost in the relation necessary to join the action of 
the muscles to the sensibility of the surface. 
Of the nerves performing the involuntary motions. 
We have just seen that nerves in great profusion come out 
upon the eyelids and forehead, and until these experiments 
were made, it was supposed that they directed the motions of 
the forehead and eyelids. But I have found that they have 
nothing to do with this function. On the contrary, a very 
small branch of the respiratory nerve of the face, that nerve 
which comes out before the ear, controuls the motions of the 
* In attempting to excite the muscles of the eye by galvanism sent through the 
fifth nerve, the muscles of the jaw were affected. 
