'"Further Note on the Sensory Nerves of the Eye-Muscles." By C. S. SHERRINGTON, M.A., M.D., F.R.S., University College, Liverpool. Received September 21, Read November 17, 1898. 

In a communication on the sensory nerves of muscles laid before the Society last year, the question previously raised as to the existence of afferent nerve fibres in the so-called "motor" cranial nerves for the muscles of the eye was advanced to the following position. Myelinated nerve-fibres from the IIIrd cranial and IVth cranial nerve-roots were traced into the tendons of the recti and oblique muscles. Since then control observations have been made. The ophthalmic division of the Vth cranial has been severed at its origin, and with it the Vlth cranial trunk. This has been done in the monkey. The condition of the nerve branches going to and lying within the muscles and tendons has been examined after an interval of twelve to fourteen days. Those of the external rectus contained nothing but degenerate nerve-fibres, save for a few fine myelinate fibres, probably from the ciliary ganglion. Those of all of the other eye-muscles contained exclusively healthy nerve-fibres. The sensorial musculo-tendinous organs of the eye-muscles are, therefore, not innervated by the ophthalmic division of the tri-geminus. On the other hand, the nerve-fibres of the external rectus muscle behave, after severance of the VIth cranial nerve, in the same way as my previous papers showed those of the other eye muscles do after section of the IIIrd and IVth nerves. 

A contribution towards the physiological inquiry into the matter has been made as follows, and has given a clear reply. The conjunctives, both palpebral and ocular, and the corneas of both eyes have been rendered deeply anaesthetic to cold, warmth, touch, and pain by liberal applications of cocaine. Then in a completely dark room the power to direct the gaze with accuracy in any required direction has been tested. The person under examination is seated, with the head securely fixed, in front of a screen. One of his hands carries a marker. The hand is moved by an assistant, and is made to mark the screen at some one point; it is then passively replaced. The person under observation during this time keeps the eyes open in the primary position or sits with them closed. He is then required to direct his gaze to the spot marked on the screen. The light is then switched on, and the point to which the gaze is turned is noted. The power to direct the gaze under these circumstances has been found to remain good. If for co-ordinate execution and ability to perform the delicate adjustments for training the eyeballs correctly in any desired position the exercise of peripheral apparatus of muscular sense is required, the only possible channels under the above conditions would seem to be deep branches of the Vth nerve or the IIIrd, IVth, and VIth so-called " motor " nerves themselves. As previously stated, the former are by both my earlier and later degeneration experiments excluded. The latter, therefore, are the only ones remaining, for the superficial branches of the Vth and the retinae are put out of action by the conditions of experiment. 

I am indebted to Mr. E. E. Laslett for carrying out the observations with me. Details regarding the methods employed and the results obtained will be given in a completer paper written in conjunction with him. 

[NB, Refs to C. S. Sherrington, ' Roy. Soc. Proc.,' vol. 61, p. 247, February, 1897. and C. S. Sherrington, ' Physiol. Soc. Proc.,' No. 3, June, 1894.]