177 
Mr. Bell on the motions of the eye, &c. 
This cannot however be said of the involuntary winking 
motions of the eyes. We have seen that in winking to avoid 
injury, the oblique muscles were in operation ; and that the 
inferior oblique muscle gained in the power of elevating the 
eye-ball by the division of the superior oblique, its opponent.* 
On the two conditions of the eye, its state of rest, and of activity. 
The eye is subject to two conditions : a state of rest with 
entire oblivion of sensation, and a state of watchfulness, 
during which both the optic nerve and the nerve of voluntary 
motion are in activity. When the eye is at rest, as in sleep, 
or even when the eye-lids are shut, the sensation on the 
retina being then neglected, the voluntary muscles resign 
their office, and the involuntary muscles draw the pupil under 
the upper eye-lid. This is the condition of the organ during 
perfect repose. 
* Since this paper was read, a case has occurred in the Middlesex Hospital, 
under the care of my colleague. Dr. Macmichael, which shows the consequences 
of the eye and eye-lids being rendered immoveable. In this case the surface 
of the eye is totally insensible, and the eye remains fixed, and directed straight 
forwards, whilst the vision is entire. The outward apparatus being without sen- 
sibility and motion, and the surface not cleared of irritating particles, inflam- 
mation has taken place, and the cornea is becoming opaque ; thus proving the 
necessity of the motions of the eye to the preservation of the organ. Another 
curious circumstance, illustrative of the observations made above, is, that when 
both eyes are shut, the eye affected continues to be sensible of a red light coming 
through the eye-lid, whilst the sound eye is in darkness. The reason of this I ap- 
prehend to be : the eye which possesses its natural motions is turned up, but 
the eye which continues fixed, looking forwards, receives the light through the 
transparent eye-lid ; and thus it appears that the dropping of the eye-lid would 
make an imperfect curtain, if unaccompanied by the turning up of the eye-ball 
during repose. 
The interest of this case will be encreased by the considerations in the Second 
Part of this Paper. 
A a 
MDCCCXXIII. 
